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Urea Cycle Made Simple - Biochemistry Video
 
02:49
Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied Urea Cycle Made Simple - Biochemistry Video LIKE US ON FACEBOOK : fb.me/Medsimplified The Urea cycle is a biochemical pathway in which the free ammonia is converted into urea so that it can be easily excreted. Urea is the major end product of nitrogen metabolism in humans. Deficiencies of the various enzymes and transporters involved in the urea cycle can cause urea cycle disorders: N-Acetylglutamate synthase deficiency Carbamoyl phosphate synthetase deficiency Ornithine transcarbamoylase deficiency Citrullinemia (Deficiency of argininosuccinic acid synthase) Argininosuccinic aciduria (Deficiency of argininosuccinic acid lyase) Argininemia (Deficiency of arginase) Hyperornithinemia, hyperammonemia, homocitrullinuria syndrome (Deficiency of the mitochondrial ornithine transporter) Most urea cycle disorders are associated with hyperammonemia, however argininemia and some forms of argininosuccinic aciduria do not present with elevated ammonia. Organisms that cannot easily and quickly remove ammonia usually have to convert it to some other substance, like urea or uric acid, which are much less toxic. Insufficiency of the urea cycle occurs in some genetic disorders (inborn errors of metabolism), and in liver failure. The result of liver failure is accumulation of nitrogenous waste, mainly ammonia, which leads to hepatic encephalopathy. Subscribe : https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw Watch Again : https://youtu.be/K3rVr_SfXo8 -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Bilirubin Metabolism Simplified
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied Bilirubin Metabolism Simplified LIKE US ON FACEBOOK : fb.me/Medsimplified Please SUPPORT MEDSIMPLIFEID BY BUYING ANYTHINGFROM AMAZON OR FLIPKART USING OUR AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN Bilirubin (formerly referred to as haematoidin) is a yellow compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates. This catabolism is a necessary process in the body's clearance of waste products that arise from the destruction of aged red blood cells. First the hemoglobin gets stripped of the heme molecule which thereafter passes through various processes of porphyrin catabolism, depending on the part of the body in which the breakdown occurs. For example, the molecules excreted in the urine differ from those in the feces.[1] The production of biliverdin from heme is the first major step in the catabolic pathway, after which the enzyme biliverdin reductase performs the second step, producing bilirubin from biliverdin. Bilirubin is excreted in bile and urine, and elevated levels may indicate certain diseases. It is responsible for the yellow color of bruises and the yellow discoloration in jaundice. Its subsequent breakdown products, such as stercobilin, cause the brown color of feces. A different breakdown product, urobilin, is the main component of the straw-yellow color in urine. Bilirubin is degraded by light. Blood collection tubes containing blood or (especially) serum to be used in bilirubin assays should be protected from illumination. For adults, blood is typically collected by needle from a vein in the arm. In newborns, blood is often collected from a heel stick, a technique that uses a small, sharp blade to cut the skin on the infant's heel and collect a few drops of blood into a small tube. Non-invasive technology is available in some health care facilities that will measure bilirubin by using an instrument placed on the skin (transcutaneous bilirubin meter) Watch Again : https://youtu.be/RwvbO-40xvw Subscribe : https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Coombs Test Made Simple
 
06:20
LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN A Coombs test (also known as Coombs' test, antiglobulin test or AGT) is either of two clinical blood tests used in immunohematology and immunology. The two Coombs tests are the direct Coombs test (DCT, also known as direct antiglobulin test or DAT), and the indirect Coombs test (also known as indirect antiglobulin test or IAT). The direct Coombs test is used to test for autoimmune hemolytic anemia; i.e., a condition of a low count of red blood cells (aka RBCs) caused by immune system lysis or breaking of RBC membranes causing RBC destruction. In certain diseases or conditions, an individual's blood may contain IgG antibodies that can specifically bind to antigens on the RBC surface membrane, and their circulating RBCs can become coated with IgG alloantibodies and/or IgG autoantibodies. Complement proteins may subsequently bind to the bound antibodies and cause RBC destruction.[1] The direct Coombs test is used to detect these antibodies or complement proteins that are bound to the surface of red blood cells; a blood sample is taken and the RBCs are washed (removing the patient's own plasma) and then incubated with anti-human globulin (also known as "Coombs reagent"). If this produces agglutination of RBCs, the direct Coombs test is positive, a visual indication that antibodies (and/or complement proteins) are bound to the surface of red blood cells. The indirect Coombs test is used in prenatal testing of pregnant women and in testing blood prior to a blood transfusion. It detects antibodies against RBCs that are present unbound in the patient's serum. In this case, serum is extracted from the blood sample taken from the patient. Then, the serum is incubated with RBCs of known antigenicity; that is, RBCs with known reference values from other patient blood samples. If agglutination occurs, the indirect Coombs test is positive.[2] The two Coombs tests are based on the fact that anti-human antibodies, which are produced by immunizing non-human species with human serum, will bind to human antibodies, commonly IgG or IgM. Animal anti-human antibodies will also bind to human antibodies that may be fixed onto antigens on the surface of red blood cells (also referred to as RBCs), and in the appropriate test tube conditions this can lead to agglutination of RBCs. The phenomenon of agglutination of RBCs is important here, because the resulting clumping of RBCs can be visualised; when clumping is seen the test is positive and when clumping is not seen the test is negative. Common clinical uses of the Coombs test include the preparation of blood for transfusion in cross-matching, screening for atypical antibodies in the blood plasma of pregnant women as part of antenatal care, and detection of antibodies for the diagnosis of immune-mediated haemolytic anemias. Examples of alloimmune hemolysis[edit] Hemolytic disease of the newborn (also known as HDN or erythroblastosis fetalis) Rh D hemolytic disease of the newborn (also known as Rh disease) ABO hemolytic disease of the newborn (the indirect Coombs test may only be weakly positive) Anti-Kell hemolytic disease of the newborn Rh c hemolytic disease of the newborn Rh E hemolytic disease of the newborn wikipidea https://en.wikipedia.org/wiki/Coombs_test Watch Again https://youtu.be/4MJA8Wzp2XM Subscribe https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Renin Angiotensin Aldosterone Sysytem - Renin Pathway easy Explanation
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied The renin–angiotensin system (RAS) or the renin–angiotensin–aldosterone system (RAAS) is a hormone system that is involved in the regulation of the plasma sodium concentration and arterial blood pressure. LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN When the plasma sodium concentration is lower than normal or the renal blood flow is reduced, the juxtaglomerular cells in the kidneys convert prorenin (an intracellular protein) into renin, which is then secreted directly into the circulation. Plasma renin then cuts a short, 10 amino acid long, peptide off a plasma protein known as angiotensinogen. The short peptide is known as angiotensin I.[2] Angiotensin I is then converted, by the removal of 2 amino acids, to form an octapeptide known as angiotensin II, by the enzyme angiotensin-converting enzyme (ACE) found in the lung capillaries. Angiotensin II is a potent vaso-active peptide that causes arterioles to constrict, resulting in increased arterial blood pressure.[3] Angiotensin II also stimulates the secretion of the hormone aldosterone from the adrenal cortex.[3] Aldosterone causes the tubular epithelial cells of the kidneys to increase the reabsorption of sodium ions from the tubular fluid back into the blood, while at the same time causing them to excrete potassium ions into the tubular fluid which will become urine. RELATED TOPICS renin catalysis protein chemical compound organic compound endocrine system polymer blood pressure angiotensin enzyme Renin-angiotensin system, physiological system that regulates blood pressure Renin is an enzyme secreted into the blood from specialized cells that encircle the arterioles at the entrance to the glomeruli of the kidneys (the renal capillary networks that are the filtration units of the kidney). The renin-secreting cells, which compose the juxtaglomerular apparatus, are sensitive to changes in blood flow and blood pressure. The primary stimulus for increased renin secretion is decreased blood flow to the kidneys, which may be caused by loss of sodium and water (as a result of diarrhea, persistent vomiting, or excessive perspiration) or by narrowing of a renal artery. Renin catalyzes the conversion of a plasma protein called angiotensinogen into a decapeptide (consisting of 10 amino acids) called angiotensin I. An enzyme in the serum called angiotensin-converting enzyme (ACE) then converts angiotensin I into an octapeptide (consisting of eight amino acids) called angiotensin II. Angiotensin II acts via receptors in the adrenal glands to stimulate the secretion of aldosterone, which stimulates salt and water reabsorption by the kidneys, and the constriction of small arteries (arterioles), which causes an increase in blood pressure. Angiotensin II further constricts blood vessels through its inhibitory actions on the reuptake into nerve terminals of the hormone norepinephrine. Watch Again https://youtu.be/fqOfOvwlz-g SUBSCRIBE https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
Просмотров: 86583 MEDSimplified
Glycolysis Pathway Made Simple !!  Biochemistry Lecture on Glycolysis
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied . Glycolysis Pathway Made Simple! Biochemistry Lecture on Glycolysis LIKE US ON FACEBOOK : https://fb.me/Medsimplified Please SUPPORT MEDSIMPLIFEID BY BUYING ANYTHINGFROM AMAZON OR FLIPKART USING OUR AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN Glycolysis (from glycose, an older term[1] for glucose + -lysis degradation) is the metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+. The free energy released in this process is used to form the high-energy molecules ATP (adenosine triphosphate) and NADH (reduced nicotinamide adenine dinucleotide). Glycolysis is a determined sequence of ten enzyme-catalyzed reactions. The intermediates provide entry points to glycolysis. For example, most monosaccharides, such as fructose and galactose, can be converted to one of these intermediates. The intermediates may also be directly useful. For example, the intermediate dihydroxyacetone phosphate (DHAP) is a source of the glycerol that combines with fatty acids to form fat. Glycolysis is an oxygen independent metabolic pathway, meaning that it does not use molecular oxygen (i.e. atmospheric oxygen) for any of its reactions. However the products of glycolysis (pyruvate and NADH + H+) are sometimes metabolized using atmospheric oxygen.[4] When molecular oxygen is used for the metabolism of the products of glycolysis the process is usually referred to as aerobic, whereas if no oxygen is used the process is said to be anaerobic.[5] Thus, glycolysis occurs, with variations, in nearly all organisms, both aerobic and anaerobic. The wide occurrence of glycolysis indicates that it is one of the most ancient metabolic pathways.[6] Indeed, the reactions that constitute glycolysis and its parallel pathway, the pentose phosphate pathway, occur metal-catalyzed under the oxygen-free conditions of the Archean oceans, also in the absence of enzymes. Glycolysis could thus have originated from chemical constraints of the prebiotic world. Glycolysis occurs in most organisms in the cytosol of the cell. The most common type of glycolysis is the Embden–Meyerhof–Parnas (EMP pathway), which was discovered by Gustav Embden, Otto Meyerhof, and Jakub Karol Parnas. Glycolysis also refers to other pathways, such as the Entner–Doudoroff pathway and various heterofermentative and homofermentative pathways. However, the discussion here will be limited to the Embden–Meyerhof–Parnas pathway. Preparatory phase The first five steps are regarded as the preparatory (or investment) phase, since they consume energy to convert the glucose into two three-carbon sugar phosphates Pay-off phase The second half of glycolysis is known as the pay-off phase, characterised by a net gain of the energy-rich molecules ATP and NADH. Since glucose leads to two triose sugars in the preparatory phase, each reaction in the pay-off phase occurs twice per glucose molecule. This yields 2 NADH molecules and 4 ATP molecules, leading to a net gain of 2 NADH molecules and 2 ATP molecules from the glycolytic pathway per glucose. Watch again : https://youtu.be/8qij1m7XUhk -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
Просмотров: 293640 MEDSimplified
Krebs Cycle Made Simple - TCA Cycle
 
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How to remember krebs cycle FOREVER : https://youtu.be/RnL71vnCMCY Follow on Instagram for the Flashcards : https://www.instagram.com/medsimplified/ Follow on FaceBook : https://goo.gl/syceUO BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN Krebs cycle The citric acid cycle – also known as the tricarboxylic acid (TCA) cycle or the Krebs cycle[1][2] – is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats and proteins into carbon dioxide and chemical energy in the form of guanosine triphosphate (GTP). In addition, the cycle provides precursors of certain amino acids as well as the reducing agent NADH that is used in numerous other biochemical reactions. Its central importance to many biochemical pathways suggests that it was one of the earliest established components of cellular metabolism and may have originated abiogenically.[3][4] The name of this metabolic pathway is derived from citric acid (a type of tricarboxylic acid) that is consumed and then regenerated by this sequence of reactions to complete the cycle. In addition, the cycle consumes acetate (in the form of acetyl-CoA) and water, reduces NAD+ to NADH, and produces carbon dioxide as a waste byproduct. The NADH generated by the TCA cycle is fed into the oxidative phosphorylation (electron transport) pathway. The net result of these two closely linked pathways is the oxidation of nutrients to produce usable chemical energy in the form of ATP. In eukaryotic cells, the citric acid cycle occurs in the matrix of the mitochondrion. In prokaryotic cells, such as bacteria which lack mitochondria, the TCA reaction sequence is performed in the cytosol with the proton gradient for ATP production being across the cell's surface (plasma membrane) rather than the inner membrane of the mitochondrion. wATCH aGAIN: https://youtu.be/ubzw64PQPqM sUBSCRIBE : https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
Просмотров: 617069 MEDSimplified
Complement System Made Easy- Immunology- Classical Alternate & Lectin pathway
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied . Complement System Made Easy- Immunology- Classical Alternate & Lectin pathway LIKE US ON FACEBOOK : fb.me/Medsimplified Please SUPPORT MEDSIMPLIFEID BY BUYING ANYTHINGFROM AMAZON OR FLIPKART USING OUR AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN The complement system is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promotes inflammation, and attacks the pathogen's plasma membrane. It is part of the innate immune system,[1] which is not adaptable and does not change over the course of an individual's lifetime. It can be recruited and brought into action by the adaptive immune system. The complement system consists of a number of small proteins found in the blood, in general synthesized by the liver, and normally circulating as inactive precursors (pro-proteins). When stimulated by one of several triggers, proteases in the system cleave specific proteins to release cytokines and initiate an amplifying cascade of further cleavages. The end result of this complement activation or complement fixation cascade is stimulation of phagocytes to clear foreign and damaged material, proxy inflammation to attract additional phagocytes, and activation of the cell-killing membrane attack complex. Over 30 proteins and protein fragments make up the complement system, including serum proteins, serosal proteins, and cell membrane receptors. They account for about 10% of the globulin fraction of blood serum and can serve as opsonins.[citation needed] Three biochemical pathways activate the complement system: the classical complement pathway, the alternative complement pathway, and the lectin pathway. Most of the proteins and glycoproteins that constitute the complement system are synthesized by hepatocytes. But significant amounts are also produced by tissue macrophages, blood monocytes, and epithelial cells of the genitourinal tract and gastrointestinal tract. The three pathways of activation all generate homologous variants of the protease C3-convertase. The classical complement pathway typically requires antigen—antibody complexes (immune complexes) for activation (specific immune response), whereas the alternative pathway can be activated by C3 hydrolysis, foreign material, pathogens, or damaged cells. The mannose-binding lectin pathway can be activated by C3 hydrolysis or antigens without the presence of antibodies (non-specific immune response). In all three pathways, C3-convertase cleaves and activates component C3, creating C3a and C3b, and causes a cascade of further cleavage and activation events. C3b binds to the surface of pathogens, leading to greater internalization by phagocytic cells by opsonization. In the alternative pathway, C3b binds to Factor B. Factor D releases Factor Ba from Factor B bound to C3b. The complex of C3b(2)Bb is a protease which cleaves C5 into C5b and C5a. C5 convertase is also formed by the Classical Pathway when C3b binds C4b and C2a. C5a is an important chemotactic protein, helping recruit inflammatory cells. C3a is the precursor of an important cytokine (adipokine) named ASP (although this is not universally accepted [6]) and is usually rapidly cleaved by carboxypeptidase B. Both C3a and C5a have anaphylatoxin activity, directly triggering degranulation of mast cells as well as increasing vascular permeability and smooth muscle contraction.[6] C5b initiates the membrane attack pathway, which results in the membrane attack complex (MAC), consisting of C5b, C6, C7, C8, and polymeric C9.[7] MAC is the cytolytic endproduct of the complement cascade; it forms a transmembrane channel, which causes osmotic lysis of the target cell. Kupffer cells and other macrophage cell types help clear complement-coated pathogens. As part of the innate immune system, elements of the complement cascade can be found in species earlier than vertebrates; most recently in the protostome horseshoe crab species, putting the origins of the system back further than was previously thought. -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Beta Oxidation of Fatty acids Made Simple-Part 1
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied Beta Oxidation of Fatty acids Part 2 https://www.youtube.com/watch?v=ZufZvbhPpws Follow on FaceBook : https://goo.gl/syceUO In biochemistry and metabolism, beta-oxidation is the catabolic process by which fatty acid molecules are broken down[1] in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA, which enters the citric acid cycle, and NADH and FADH2, which are co-enzymes used in the electron transport chain. It is named as such because the beta carbon of the fatty acid undergoes oxidation to a carbonyl group. Beta-oxidation is primarily facilitated by the mitochondrial trifunctional protein, an enzyme complex associated with the inner mitochondrial membrane, although some fatty acids are oxidized in peroxisomes. Fatty acid catabolism consists of: Activation and membrane transport of free fatty acids by binding to coenzyme A. Oxidation of the beta carbon to a carbonyl group. Cleavage of two-carbon segments resulting in acetyl-CoA. Oxidation of acetyl-CoA to carbon dioxide in the citric acid cycle. Electron transfer from electron carriers to the electron transport chain in oxidative phosphorylation. -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
Просмотров: 182298 MEDSimplified
Olfactory Pathway - Nerve and Tracts
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN The olfactory nerve (Latin: nervus olfactorius) is typically considered the first cranial nerve, or simply CN I. It contains the afferent nerve fibers of the olfactory receptor neurons, transmitting nerve impulses about odors to the central nervous system, where they are perceived by the sense of smell (olfaction). Derived from the embryonic nasal placode, the olfactory nerve is somewhat unique among cranial nerves because it is capable of some regeneration if damaged. The olfactory nerve is sensory in nature and originates on the olfactory mucosa in the upper part of the nasal cavity.[1] From the olfactory mucosa, the nerve (actually many small nerve fascicles) travels up through the cribriform plate of the ethmoid bone to reach the surface of the brain. Here the fascicles enter the olfactory bulb and synapse there; from the bulbs (one on each side) the olfactory information is transmitted into the brain via the olfactory tract.[2] The fascicles of the olfactory nerve are not visible on a cadaver brain because they are severed upon removal Follow on FaceBook : https://goo.gl/syceUO BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN Structure[edit] The specialized olfactory receptor neurons of the olfactory nerve are located in the olfactory mucosa of the upper parts of the nasal cavity. The olfactory nerves consist of a collection of many sensory nerve fibers that extend from the olfactory epithelium to the olfactory bulb, passing through the many openings of the cribriform plate of the ethmoid bone, a sieve-like structure. The sense of smell (olfaction) arises from the stimulation of receptors by small molecules in inspired air of varying spatial, chemical, and electrical properties that reach the nasal epithelium in the nasal cavity during inhalation. These stimulants are transduced into electrical activity in the olfactory neurons, which then transmit these impulses to the olfactory bulb and from there to the rest of the central nervous system via the olfactory tract. The olfactory nerve is the shortest of the twelve cranial nerves and, similar to the optic nerve, does not emanate from the brainstem.[2] Subscribe https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw Watch Again https://youtu.be/zN6-Eka5jRA -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Meckel's Diverticulum Made Easy
 
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LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN A Meckel's diverticulum, a true congenital diverticulum, is a slight bulge in the small intestine present at birth and a vestigial remnant of the omphalomesenteric duct (also called the vitelline duct or yolk stalk). It is the most common malformation of the gastrointestinal tract and is present in approximately 2% of the population,[1] with males more frequently experiencing symptoms. Meckel's diverticulum was first explained by Fabricius Hildanus in the sixteenth century and later named after Johann Friedrich Meckel, who described the embryological origin of this type of diverticulum in 1809 Meckel's diverticulum is located in the distal ileum, usually within 60–100 cm (2 feet) of the ileocecal valve. This blind segment or small pouch is about 3–6 cm long and may have a greater lumen diameter than that of the ileum.[4] It runs antimesenterically and has its own blood supply. It is a remnant of the connection from the yolk sac to the small intestine present during embryonic development. It is a true diverticulum, consisting of all 3 layers of the bowel wall which are mucosa, submucosa and muscularis propria.[5] As the vitelline duct is made up of pluripotent cell lining, Meckel’s diverticulum may harbor abnormal tissues, containing embryonic remnants of other tissue types. Jejunal, duodenal mucosa or Brunner's tissue were each found in 2% of ectopic cases. Heterotopic rests of gastric mucosa and pancreatic tissue are seen in 60% and 6% of cases respectively. Heterotopic means the displacement of an organ from its normal anatomic location.[6] Inflammation of this Meckel's diverticulum may mimic appendicitis. Therefore during appendectomy, ileum should be checked for the presence of Meckel's diverticulum, if it is found to be present it should be removed along with appendix. A memory aid is the rule of 2s:[7] 2% (of the population) 2 feet (proximal to the ileocecal valve) 2 inches (in length) 2 types of common ectopic tissue (gastric and pancreatic) 2 years is the most common age at clinical presentation 2:1 male:female ratioSymptoms[edit] The majority of people with a Meckel's diverticulum are asymptomatic. An asymptomatic Meckel's diverticulum is called a silent Meckel's diverticulum.[9] If symptoms do occur, they typically appear before the age of two years. The most common presenting symptom is painless rectal bleeding such as melaena-like black offensive stools, followed by intestinal obstruction, volvulus and intussusception. Occasionally, Meckel's diverticulitis may present with all the features of acute appendicitis. Also, severe pain in the epigastric region is experienced by the patient along with bloating in the epigastric and umbilical regions. At times, the symptoms are so painful that they may cause sleepless nights with acute pain felt in the foregut region, specifically in the epigastric and umbilical regions. In most cases, bleeding occurs without warning and stops spontaneously. The symptoms can be extremely painful, often mistaken as just stomach pain resulting from not eating or constipation. Diagnosis[edit] Technetium-99m Pertechnetate Scan with a Meckel's Diverticulum. A technetium-99m (99mTc) pertechnetate scan, also called Meckel scan, is the investigation of choice to diagnose Meckel's diverticula in children. This scan detects gastric mucosa; since approximately 50% of symptomatic Meckel's diverticula have ectopic gastric or pancreatic cells contained within them,[10] this is displayed as a spot on the scan distant from the stomach itself. In children, this scan is highly accurate and noninvasive, with 95% specificity and 85% sensitivity;[5] however, in adults the test is only 9% specific and 62% sensitive.[11] Patients with these misplaced gastric cells may experience peptic ulcers as a consequence. Therefore, other tests such as colonoscopy and screenings for bleeding disorders should be performed, and angiography can assist in determining the location and severity of bleeding. Colonoscopy might be helpful to rule out other sources of bleeding but it is not used as an identification tool. https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw watch again https://youtu.be/nQ8rZFhy_QA -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
Просмотров: 49054 MEDSimplified
Electron Transport Chain ETC Made Easy
 
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Electron Transport Chain ETC Made Easy Follow on Instagram for the Flashcards : https://www.instagram.com/medsimplified/ LIKE US ON FACEBOOK : https://fb.me/Medsimplified GLYCOLYSIS : https://www.youtube.com/watch?v=8qij1m7XUhk KREBS CYCLE : https://www.youtube.com/watch?v=ubzw64PQPqM&t=181s Beta oxidation: https://www.youtube.com/watch?v=__jS-pjzb5k&t=5s An electron transport chain (ETC) is a series of complexes that transfer electrons from electron donors to electron acceptors via redox (both reduction and oxidation occurring simultaneously) reactions, and couples this electron transfer with the transfer of protons (H+ ions) across a membrane. This creates an electrochemical proton gradient that drives the synthesis of adenosine triphosphate (ATP), a molecule that stores energy chemically in the form of highly strained bonds. The molecules of the chain include peptides, enzymes (which are proteins or protein complexes), and others. The final acceptor of electrons in the electron transport chain during aerobic respiration is molecular oxygen although a variety of acceptors other than oxygen such as sulfate exist in anaerobic respiration. In chloroplasts, light drives the conversion of water to oxygen and NADP+ to NADPH with transfer of H+ ions across chloroplast membranes. In mitochondria, it is the conversion of oxygen to water, NADH to NAD+ and succinate to fumarate that are required to generate the proton gradient. Complex I In Complex I (NADH:ubiquinone oxidoreductase, NADH-CoQ reductase, or NADH dehydrogenase; EC 1.6.5.3), two electrons are removed from NADH and ultimately transferred to a lipid-soluble carrier, ubiquinone (Q). The reduced product, ubiquinol (QH2), freely diffuses within the membrane, and Complex I translocates four protons (H+) across the membrane, thus producing a proton gradient. Complex I is one of the main sites at which premature electron leakage to oxygen occurs, thus being one of the main sites of production of superoxide. The pathway of electrons is as follows: NADH is oxidized to NAD+, by reducing Flavin mononucleotide to FMNH2 in one two-electron step. FMNH2 is then oxidized in two one-electron steps, through a semiquinone intermediate. Each electron thus transfers from the FMNH2 to an Fe-S cluster, from the Fe-S cluster to ubiquinone (Q). Transfer of the first electron results in the free-radical (semiquinone) form of Q, and transfer of the second electron reduces the semiquinone form to the ubiquinol form, QH2. During this process, four protons are translocated from the mitochondrial matrix to the intermembrane space. [4] As the electrons become continuously oxidized and reduced throughout the complex an electron current is produced along the 180 Angstrom width of the complex within the membrane. This current powers the active transport of four protons to the intermembrane space per two electrons from NADH. Complex II In Complex II (succinate dehydrogenase or succinate-CoQ reductase; EC 1.3.5.1) additional electrons are delivered into the quinone pool (Q) originating from succinate and transferred (via flavin adenine dinucleotide (FAD)) to Q. Complex II consists of four protein subunits: succinate dehydrogenase, (SDHA); succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial, (SDHB); succinate dehydrogenase complex subunit C, (SDHC) and succinate dehydrogenase complex, subunit D, (SDHD). Other electron donors (e.g., fatty acids and glycerol 3-phosphate) also direct electrons into Q (via FAD). Complex 2 is a parallel electron transport pathway to complex 1, but unlike complex 1, no protons are transported to the intermembrane space in this pathway. Therefore, the pathway through complex 2 contributes less energy to the overall electron transport chain process. Complex III In Complex III (cytochrome bc1 complex or CoQH2-cytochrome c reductase; EC 1.10.2.2), the Q-cycle contributes to the proton gradient by an asymmetric absorption/release of protons. Two electrons are removed from QH2 at the QO site and sequentially transferred to two molecules of cytochrome c, a water-soluble electron carrier located within the intermembrane space. The two other electrons sequentially pass across the protein to the Qi site where the quinone part of ubiquinone is reduced to quinol. A proton gradient is formed by one quinol (2H+2e-) oxidations at the Qo site to form one quinone (2H+2e-) at the Qi site. (in total four protons are translocated: two protons reduce quinone to quinol and two protons are released from two ubiquinol molecules). QH2 + 2 cytochrome c (FeIII) + 2 H+in → Q + 2 cytochrome c (FeII) + 4 H+out When electron transfer is reduced (by a high membrane potential or respiratory inhibitors such as antimycin A), Complex III may leak electrons to molecular oxygen, resulting in superoxide formation. -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Gluconeogenesis Pathway Made Simple - BIOCHEMISTERY
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied Gluconeogenesis Follow on FaceBook : https://goo.gl/syceUO BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN Gluconeogenesis (GNG) is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. From breakdown of proteins, these substrates include glucogenic amino acids (although not ketogenic amino acids); from breakdown of lipids (such as triglycerides), they include glycerol (although not fatty acids); and from other steps in metabolism they include pyruvate and lactate. Gluconeogenesis is one of several main mechanisms used by humans and many other animals to maintain blood glucose levels, avoiding low levels (hypoglycemia). Other means include the degradation of glycogen (glycogenolysis),[1] fatty acid breakdown. Gluconeogenesis is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms.[2] In vertebrates, gluconeogenesis takes place mainly in the liver and, to a lesser extent, in the cortex of the kidneys. In ruminants, this tends to be a continuous process.[3] In many other animals, the process occurs during periods of fasting, starvation, low-carbohydrate diets, or intense exercise. The process is highly endergonic until it is coupled to the hydrolysis of ATP or GTP, effectively making the process exergonic. For example, the pathway leading from pyruvate to glucose-6-phosphate requires 4 molecules of ATP and 2 molecules of GTP to proceed spontaneously. Gluconeogenesis is often associated with ketosis. Gluconeogenesis is also a target of therapy for type 2 diabetes, such as the antidiabetic drug, metformin, which inhibits glucose formation and stimulates glucose uptake by cells.[4] In ruminants, because dietary carbohydrates tend to be metabolized by rumen organisms, gluconeogenesis occurs regardless of fasting, low-carbohydrate diets, exercise, etc -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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GABA Receptor( BZD) - Structure and Mechanism of Action
 
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GABA Receptor - Structure and Mechanism of Action Follow on Instagram for the Flashcards : https://www.instagram.com/medsimplified/ LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Immunoglobulins Structure and Function /Antibody Structure Types and Function
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied Immunoglobulins/Antibody Structure Types and Function LIKE US ON FACEBOOK : fb.me/Medsimplified Antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shape protein produced by plasma cells that is used by the immune system to identify and neutralize pathogens such as bacteria and viruses. The antibody recognizes a unique molecule of the harmful agent, called an antigen, via the variable region Each tip of the "Y" of an antibody contains a paratope (analogous to a lock) that is specific for one particular epitope (similarly analogous to a key) on an antigen, allowing these two structures to bind together with precision. Using this binding mechanism, an antibody can tag a microbe or an infected cell for attack by other parts of the immune system, or can neutralize its target directly (for example, by blocking a part of a microbe that is essential for its invasion and survival). Antibodies are glycoproteins belonging to the immunoglobulin superfamily; ] the terms antibody and immunoglobulin are often used interchangeably. Though strictly speaking, an antibody is not the same as an immunoglobulin; B cells can produce two types of immunoglobulins - surface immunoglobulins, which are B cell receptors; and secreted immunoglobulins, which are antibodies. So antibodies are one of two classes of immunoglobulins. Though the general structure of all antibodies is very similar, a small region at the tip of the protein is extremely variable, allowing millions of antibodies with slightly different tip structures, or antigen-binding sites, to exist. This region is known as the hypervariable region. Each of these variants can bind to a different antigen. This enormous diversity of antibody paratopes on the antigen-binding fragments allows the immune system to recognize an equally wide variety of antigens The large and diverse population of antibody paratope is generated by random recombination events of a set of gene segments that encode different antigen-binding sites (or paratopes), followed by random mutations in this area of the antibody gene, which create further diversity.[ This recombinational process that produces clonal antibody paratope diversity is called V(D)J or VJ recombination. Basically, the antibody paratope is polygenic, made up of three genes, V, D, and J. Each paratope locus is also polymorphic, such that during antibody production, one allele of V, one of D, and one of J is chosen. These gene segments are then joined together using random genetic recombination to produce the paratope. The regions where the genes are randomly recombined together is the hyper variable region used to recognise different antigens on a clonal basis. IgA Found in mucosal areas, such as the gut, respiratory tract and urogenital tract, and prevents colonization by pathogens.[14] Also found in saliva, tears, and breast milk. Some antibodies form complexes that bind to multiple antigen molecules. IgD Functions mainly as an antigen receptor on B cells that have not been exposed to antigens. ] It has been shown to activate basophils and mast cells to produce antimicrobial factors. IgE Binds to allergens and triggers histamine release from mast cells and basophils, and is involved in allergy. Also protects against parasitic worms IgG In its four forms, provides the majority of antibody-based immunity against invading pathogens. The only antibody capable of crossing the placenta to give passive immunity to the fetus. IgM Expressed on the surface of B cells (monomer) and in a secreted form (pentamer) with very high avidity. Eliminates pathogens in the early stages of B cell-mediated (humoral) immunity before there is sufficient IgG Subscribe to my Channel : https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw Watch Again : https://youtu.be/vxWf-66lymg -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Dorsal Column Medial Leminiscus Pathway  Made Easy - Spinal Cord Tracts 1
 
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Dorsal coloumn medial leminiscus Pathway Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied LIKE US ON FACEBOOK : fb.me/Medsimplified Posterior column–medial lemniscus pathway (PCML) (also known as the dorsal column-medial lemniscus pathway) is a sensory pathway of the central nervous system that conveys localized sensations of fine touch, vibration, two-point discrimination, and proprioception (position sense) from the skin and joints. It transmits information from the body to the postcentral gyrus of the cerebral cortex. There are three neurons involved in the pathway: first-order neurons, second-order neurons, and third-order neurons. The first-order neurons reside in dorsal root ganglia and send their axons through the gracile fasciculus and cuneate fasciculus.[The first-order axons make contact with second order neurons at the gracile and cuneate nuclei in the lower medulla. The second-order neurons send their axons to the thalamus. The third order neurons arise from thalamus to the postcentral gyrus. The posterior column is composed of gracile fasciculus and cuneate fasciculus. The gracile fasciculus carries input from the lower half of the body and the cuneate fasciculus carries input from the upper half of the body. The gracile fasciculus arise from the fibers more medial than the cuneate fasciculus. When the axons of second-order neurons of the dorsal column system decussate in the medulla, they are called internal arcuate fibers. The crossings of the internal arcuate fibers form the medial lemniscus. The name comes from the two structures that the sensation travels up: the posterior (or dorsal) column of the spinal cord, and the medial lemniscus in the brainstem. The PCML pathway is composed of rapidly conducting, large, myelinated fibers. First neuron This fine sensation is detected by mechanoreceptors called tactile corpuscles that lie in the dermis of the skin close to the epidermis. When these structures are stimulated by slight pressure, an action potential is started. Alternatively, proprioceptive muscle spindles and other skin surface touch receptors such as Merkel cells, bulbous corpuscles, lamellar corpuscles, and hair follicle receptors (peritrichial endings) may involve the first neuron in this pathway. Example of a pseudounipolar neuron. Note the single process (axon) originating from the cell body then splitting into two branches. The sensory neurons in this pathway are pseudounipolar, meaning that they have a single process emanating from the soma (also known as the cell body, perikaryon, or cyton) with two distinct branches: one peripheral branch that functions somewhat like a dendrite of a typical neuron by receiving input (although it should not be confused with a true dendrite), and one central branch that functions like a typical axon by carrying information to other neurons (again, both branches are actually part of one axon). Watch again : https://youtu.be/e6FjZCkLEUk -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Spinothalamic Tract Made Easy - Spinal Cord Tracts 1
 
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Spinothalamic Tract Made Easy Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied LIKE US ON FACEBOOK : https://fb.me/Medsimplified The spinothalamic tract (also known as anterolateral system or the ventrolateral system) is a sensory pathway from the skin to the thalamus. From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory cortex of the postcentral gyrus. The spinothalamic tract consists of two adjacent pathways: anterior and lateral. The anterior spinothalamic tract carries information about crude touch. The lateral spinothalamic tract conveys pain and temperature. In the spinal cord, the spinothalamic tract has somatotopic organization. This is the segmental organization of its cervical, thoracic, lumbar, and sacral components, which is arranged from most medial to most lateral respectively. The pathway decussates at the level of the spinal cord, rather than in the brainstem like the posterior column-medial lemniscus pathway and lateral corticospinal tract. Watch Again: https://youtu.be/jqLlt3QQhcE -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Coagulation Cascade SIMPLEST EXPLANATION !! The Extrinsic and Intrinsic Pathway of HEMOSTASIS
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied Coagulation Cascade SIMPLEST EXPLANATION Follow on FaceBook : https://goo.gl/syceUO Coagulation (also known as clotting) is the process by which blood changes from a liquid to a gel, forming a clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism of coagulation involves activation, adhesion, and aggregation of platelets along with deposition and maturation of fibrin. Disorders of coagulation are disease states which can result in bleeding (hemorrhage or bruising) or obstructive clotting (thrombosis).[1] LIKE ON FACEBOOK : The coagulation factors are generally serine proteases (enzymes), which act by cleaving downstream proteins. There are some exceptions. For example, FVIII and FV are glycoproteins, and Factor XIII is a transglutaminase.[7] The coagulation factors circulate as inactive zymogens. The coagulation cascade is therefore classically divided into three pathways. The tissue factor and contact activation pathways both activate the "final common pathway" of factor X, thrombin and fibrin Tissue factor pathway (extrinsic)[edit] The main role of the tissue factor pathway is to generate a "thrombin burst", a process by which thrombin, the most important constituent of the coagulation cascade in terms of its feedback activation roles, is released very rapidly. FVIIa circulates in a higher amount than any other activated coagulation factor. The process includes the following steps:[7] Following damage to the blood vessel, FVII leaves the circulation and comes into contact with tissue factor (TF) expressed on tissue-factor-bearing cells (stromal fibroblasts and leukocytes), forming an activated complex (TF-FVIIa). TF-FVIIa activates FIX and FX. FVII is itself activated by thrombin, FXIa, FXII and FXa. The activation of FX (to form FXa) by TF-FVIIa is almost immediately inhibited by tissue factor pathway inhibitor (TFPI). FXa and its co-factor FVa form the prothrombinase complex, which activates prothrombin to thrombin. Thrombin then activates other components of the coagulation cascade, including FV and FVIII (which activates FXI, which, in turn, activates FIX), and activates and releases FVIII from being bound to vWF. FVIIIa is the co-factor of FIXa, and together they form the "tenase" complex, which activates FX; and so the cycle continues. ("Tenase" is a contraction of "ten" and the suffix "-ase" used for enzymes.) Contact activation pathway (intrinsic)[edit] The contact activation pathway begins with formation of the primary complex on collagen by high-molecular-weight kininogen (HMWK), prekallikrein, and FXII (Hageman factor). Prekallikrein is converted to kallikrein and FXII becomes FXIIa. FXIIa converts FXI into FXIa. Factor XIa activates FIX, which with its co-factor FVIIIa form the tenase complex, which activates FX to FXa. The minor role that the contact activation pathway has in initiating clot formation can be illustrated by the fact that patients with severe deficiencies of FXII, HMWK, and prekallikrein do not have a bleeding disorder. Instead, contact activation system seems to be more involved in inflammation.[7] Final common pathway[edit] The division of coagulation in two pathways is mainly artificial, it originates from laboratory tests in which clotting times were measured after the clotting was initiated by glass (intrinsic pathway) or by thromboplastin (a mix of tissue factor and phospholipids). In fact thrombin is present from the very beginning, already when platelets are making the plug. Thrombin has a large array of functions, not only the conversion of fibrinogen to fibrin, the building block of a hemostatic plug. In addition, it is the most important platelet activator and on top of that it activates Factors VIII and V and their inhibitor protein C (in the presence of thrombomodulin), and it activates Factor XIII, which forms covalent bonds that crosslink the fibrin polymers that form from activated monomers.[7] Following activation by the contact factor or tissue factor pathways, the coagulation cascade is maintained in a prothrombotic state by the continued activation of FVIII and FIX to form the tenase complex, until it is down-regulated by the anticoagulant pathways SUBSCRIBE https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw WATCH AGAIN https://www.youtube.com/watch?v=LVYmV5mK6QI -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Trigeminal Nerve Anatomy - Cranial Nerve 5 Course and Distribution
 
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LIKE US ON FACEBOOK : fb.me/Medsimplified Follow on Instagram for the Flashcards : https://www.instagram.com/medsimplified/ BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN The trigeminal nerve (the fifth cranial nerve, or simply CN V) is a nerve responsible for sensation in the face and motor functions such as biting and chewing. The largest of the cranial nerves, its name ("trigeminal" = tri-, or three and -geminus, or twin; thrice-twinned) derives from the fact that each trigeminal nerve (one on each side of the pons) has three major branches: the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3). The ophthalmic and maxillary nerves are purely sensory, and the mandibular nerve has sensory (or "cutaneous") and motor functions The three major branches of the trigeminal nerve—the ophthalmic nerve (V1), the maxillary nerve (V2) and the mandibular nerve (V3)—converge on the trigeminal ganglion (also called the semilunar ganglion or gasserian ganglion), located within Meckel's cave and containing the cell bodies of incoming sensory-nerve fibers. The trigeminal ganglion is analogous to the dorsal root ganglia of the spinal cord, which contain the cell bodies of incoming sensory fibers from the rest of the body. From the trigeminal ganglion a single, large sensory root enters the brainstem at the level of the pons. Immediately adjacent to the sensory root, a smaller motor root emerges from the pons at the same level. Motor fibers pass through the trigeminal ganglion on their way to peripheral muscles, but their cell bodies are located in the nucleus of the fifth nerve, deep within the pons. V1/V2 distribution - Referring to the ophthalmic and maxillary branches V2/V3 distribution - Referring to the maxillary and mandibular branches V1-V3 distribution - Referring to all three branches The complex processing of pain-temperature information in the thalamus and cerebral cortex (as opposed to the relatively simple, straightforward processing of touch-position information) reflects a phylogenetically older, more primitive sensory system. The detailed information received from peripheral touch-position receptors is superimposed on a background of awareness, memory and emotions partially set by peripheral pain-temperature receptors. Although thresholds for touch-position perception are relatively easy to measure, those for pain-temperature perception are difficult to define and measure. "Touch" is an objective sensation, but "pain" is an individualized sensation which varies among different people and is conditioned by memory and emotion. Anatomical differences between the pathways for touch-position perception and pain-temperature sensation help explain why pain, especially chronic pain, is difficult to manage. Wallenberg syndrome (lateral medullary syndrome) is a clinical demonstration of the anatomy of the trigeminal nerve, summarizing how it processes sensory information. A stroke usually affects only one side of the body; loss of sensation due to a stroke will be lateralized to the right or the left side of the body. The only exceptions to this rule are certain spinal-cord lesions and the medullary syndromes, of which Wallenberg syndrome is the best-known example. In this syndrome, a stroke causes a loss of pain-temperature sensation from one side of the face and the other side of the body. This is explained by the anatomy of the brainstem. In the medulla, the ascending spinothalamic tract (which carries pain-temperature information from the opposite side of the body) is adjacent to the ascending spinal tract of the trigeminal nerve (which carries pain-temperature information from the same side of the face). A stroke which cuts off the blood supply to this area (for example, a clot in the posterior inferior cerebellar artery) destroys both tracts simultaneously. The result is a loss of pain-temperature (but not touch-position) sensation in a "checkerboard" pattern (ipsilateral face, contralateral body), facilitating diagnosis. -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Spermatogenesis Made Easy
 
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Spermatogenesis is the process in whichspermatozoa are produced fromspermatogonial stem cells by way of mitosisand meiosis. The initial cells in this pathway are called spermatogonia, which yield primaryspermatocytes by mitosis. The primary spermatocyte divides meiotically (Meiosis I) into two secondary spermatocytes; each secondary spermatocyte divides into twospermatids by Meiosis II. These develop into mature spermatozoa, also known as spermcells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa. Spermatozoa are the mature male gametes in many sexually reproducing organisms. Thus, spermatogenesis is the male version ofgametogenesis, of which the female equivalent is oogenesis. In mammals it occurs in the seminiferous tubules of the male testes in a stepwise fashion. Spermatogenesis is highly dependent upon optimal conditions for the process to occur correctly, and is essential for sexual reproduction. DNA methylation and histone modification have been implicated in the regulation of this process.[2] It starts atpuberty and usually continues uninterrupted until death, although a slight decrease can be discerned in the quantity of produced sperm with increase in age The entire process of spermatogenesis can be broken up into several distinct stages, each corresponding to a particular type of cell in human. In the following table, ploidy, copy number and chromosome/chromatid counts are for one cell, generally prior to DNA synthesis and division (in G1 if applicable). The primary spermatocyte is arrested after DNA synthesis and prior to division. Spermatocytogenesis is the male form ofgametocytogenesis and results in the formation of spermatocytes possessing half the normal complement of genetic material. In spermatocytogenesis, a diploidspermatogonium, which resides in the basal compartment of the seminiferous tubules, divides mitotically, producing two diploid intermediate cells called primary spermatocytes. Each primary spermatocyte then moves into the adluminal compartmentof the seminiferous tubules and duplicates its DNA and subsequently undergoes meiosis I to produce two haploid secondary spermatocytes, which will later divide once more into haploid spermatids. This division implicates sources of genetic variation, such as random inclusion of either parental chromosomes, and chromosomal crossover, to increase the genetic variability of the gamete. -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Facial Nerve Anatomy - Course , Nuclei , Branches etc
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied LIKE US ON FACEBOOK : fb.me/Medsimplified Follow on Instagram for the Flashcards : https://www.instagram.com/medsimplified/ The facial nerve is the seventh cranial nerve, or simply cranial nerve VII. It emerges from the brainstem between the pons and the medulla, controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity. It also supplies preganglionic parasympathetic fibers to several head and neck ganglia. Nucleus[edit] The cell bodies for the facial nerve are grouped in anatomical areas called nuclei or ganglia. The cell bodies for the afferent nerves are found in the geniculate ganglion for taste sensation. The cell bodies for muscular efferent nerves are found in the facial motor nucleus whereas the cell bodies for the parasympathetic efferent nerves are found in the superior salivatory nucleus. Intracranial branches[edit] Greater petrosal nerve - provides parasympathetic innervation to several glands, including the nasal gland, palatine gland, lacrimal gland, and pharyngeal gland. It also provides parasympathetic innervation to the sphenoid sinus, frontal sinus, maxillary sinus, ethmoid sinus and nasal cavity. Nerve to stapedius - provides motor innervation for stapedius muscle in middle ear Chorda tympani Submandibular gland Sublingual gland Special sensory taste fibers for the anterior 2/3 of the tongue. Extracranial branches[edit] Distal to stylomastoid foramen, the following nerves branch off the facial nerve: Posterior auricular nerve - controls movements of some of the scalp muscles around the ear Branch to Posterior belly of Digastric muscle as well as the Stylohyoid muscle Five major facial branches (in parotid gland) - from top to bottom (a helpful mnemonic being To Zanzibar By Motor Car): Temporal branch Zygomatic branch Buccal branch Marginal mandibular branch Cervical branch Function[edit] Facial expression[edit] The main function of the facial nerve is motor control of most of the muscles of facial expression. It also innervates the posterior belly of the digastric muscle, the stylohyoid muscle, and the stapedius muscle of the middle ear. All of these muscles are striated muscles of branchiomeric origin developing from the 2nd pharyngeal arch. Facial sensation[edit] In addition, the facial nerve receives taste sensations from the anterior two-thirds of the tongue via the chorda tympani; taste sensation is sent to the gustatory portion (superior part) of the solitary nucleus. General sensation from the anterior two-thirds of tongue are supplied by afferent fibers of the third division of the fifth cranial nerve (V-3). These sensory (V-3) and taste (VII) fibers travel together as the lingual nerve briefly before the chorda tympani leaves the lingual nerve to enter the tympanic cavity (middle ear) via the petrotympanic fissure. It joins the rest of the facial nerve via the canaliculus for chorda tympani. The facial nerve then forms the geniculate ganglion, which contains the cell bodies of the taste fibers of chorda tympani and other taste and sensory pathways. From the geniculate ganglion the taste fibers continue as the intermediate nerve which goes to the upper anterior quadrant of the fundus of the internal acoustic meatus along with the motor root of the facial nerve. The intermediate nerve reaches the posterior cranial fossa via the internal acoustic meatus before synapsing in the solitary nucleus. The facial nerve also supplies a small amount of afferent innervation to the oropharynx below the palatine tonsil. There is also a small amount of cutaneous sensation carried by the nervus intermedius from the skin in and around the auricle (outer ear). The facial nerve also supplies parasympathetic fibers to the submandibular gland and sublingual glands via chorda tympani. Parasympathetic innervation serves to increase the flow of saliva from these glands. It also supplies parasympathetic innervation to the nasal mucosa and the lacrimal gland via the pterygopalatine ganglion. The parasympathetic fibers that travel in the facial nerve originate in the superior salivary nucleus. The facial nerve also functions as the efferent limb of the corneal reflex. Finally, the facial nerve also carries axons of type GVA, general visceral afferent, which provide sensation to the soft palate and parts of the nasal cavity. -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Neuromuscular Junction (NMJ) Structure and Action
 
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LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN A neuromuscular junction (or myoneural junction) is a chemical synapse formed by the contact between a motor neuron and a muscle fiber.[1] It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the muscle fiber, causing muscle contraction. Muscles require innervation to function—and even just to maintain muscle tone, avoiding atrophy. Synaptic transmission at the neuromuscular junction begins when an action potential reaches the presynaptic terminal of a motor neuron, which activates voltage-dependent calcium channels to allow calcium ions to enter the neuron. Calcium ions bind to sensor proteins (synaptotagmin) on synaptic vesicles, triggering vesicle fusion with the cell membrane and subsequent neurotransmitter release from the motor neuron into the synaptic cleft. In vertebrates, motor neurons release acetylcholine (ACh), a small molecule neurotransmitter, which diffuses across the synaptic cleft and binds to nicotinic acetylcholine receptors (nAChRs) on the cell membrane of the muscle fiber, also known as the sarcolemma. nAChRs are ionotropic receptors, meaning they serve as ligand-gated ion channels. The binding of ACh to the receptor can depolarize the muscle fiber, causing a cascade that eventually results in muscle contraction. Neuromuscular junction diseases can be of genetic and autoimmune origin. Genetic disorders, such as Duchenne muscular dystrophy, can arise from mutated structural proteins that comprise the neuromuscular junction, whereas autoimmune diseases, such as myasthenia gravis, occur when antibodies are produced against nicotinic acetylcholine receptors on the sarcolemma. The neuromuscular junction differs from chemical synapses between neurons. Presynaptic motor axons stop 30 nanometers from the sarcolemma, the cell membrane of a muscle cell. This 30-nanometer space forms the synaptic cleft through which signalling molecules are released. The sarcolemma has invaginations called postjunctional folds, which increase the surface area of the membrane exposed to the synaptic cleft.[2] These postjunctional folds form what is referred to as the motor endplate, which possess nicotinic acetylcholine receptors (nAChRs) at a density of 10,000 receptors/micrometer2 in skeletal muscle.[3] The presynaptic axons form bulges called terminal boutons (or presynaptic terminals) that project into the postjunctional folds of the sarcolemma. The presynaptic terminals have active zones that contain vesicles, quanta, full of acetylcholine molecules. These vesicles can fuse with the presynaptic membrane and release ACh molecules into the synaptic cleft via exocytosis after depolarization.[2] AChRs are localized opposite the presynaptic terminals by protein scaffolds at the postjunctional folds of the sarcolemma. Dystrophin, a structural protein, connects the sarcomere, sarcolemma, and extracellular matrix components. Rapsyn is another protein that docks AChRs and structural proteins to the cytoskeleton. Also present is the receptor tyrosine kinase protein MuSK, a signaling protein involved in the development of the neuromuscular junction, which is also held in place by rapsyn.[2] Mechanism of action The neuromuscular junction is where a neuron activates a muscle to contract. Upon the arrival of an action potential at the presynaptic neuron terminal, voltage-dependent calcium channels open and Ca2+ ions flow from the extracellular fluid into the presynaptic neuron's cytosol. This influx of Ca2+ causes neurotransmitter-containing vesicles to dock and fuse to the presynaptic neuron's cell membrane through SNARE proteins. Fusion of the vesicular membrane with the presynaptic cell membrane results in the emptying of the vesicle's contents (acetylcholine) into the synaptic cleft, a process known as exocytosis. Acetylcholine diffuses into the synaptic cleft and can bind to the nicotinic acetylcholine receptors on the motor endplate. wATCH aGAIN https://youtu.be/4GzN4p_xWj4 -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Weil Felix Test
 
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Weil felix Test LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN is an agglutination test for the diagnosis of rickettsial infections. It was first described in 1916. By virtue of its long history and of its simplicity, it has been one of the most widely employed tests for rickettsia on a global scale, despite being superseded in many settings by more sensitive and specific diagnostic tests. The basis of the test is the presence of antigenic cross-reactivity between Rickettsia spp. and certain serotypes of non-motile Proteus spp., a phenomenon first published by Edmund Weil and Arthur Felix in 1916.[1] The serum of patients diagnosed with epidemic typhus was found to agglutinate in the presence of bacteria now known as Proteus vulgaris. Ensuing work elucidated that it was in fact the somatic (O) antigen that cross-reacted with anti-rickettsial antibodies, and furthermore, that different Proteus O antigens would cross-react with different species of Rickettsia. Typhus group rickettsiae (Rickettsia prowazekii, R. typhi) react with P. vulgaris OX19, and scrub typhus (Orientia tsutsugamushi) reacts with P. mirabilis OXK. The spotted fever group rickettsiae (R. rickettsii, R. africae, R. japonica, etc.) react with P. vulgaris OX2 and OX19, to varying degrees, depending on the species.[2] The Weil–Felix test suffers from poor sensitivity and specificity, with a recent study showing an overall sensitivity as low as 33% and specificity of 46%.[3] Other studies have had similar findings.[4] As a result, it has largely been supplanted by other methods of serology, including indirect immunofluorescence antibody (IFA) testing, which is the gold standard. However, in resource-limited settings, it still remains an important tool in the diagnosis and identification of public health concerns, such as outbreaks of epidemic typhus. Slide method[edit] On a solid surface (glass slide, tile, card), a small amount (50–100 μL) of the patient’s serum is placed. A single drop of the desired antigen is added, and the resulting suspension is mixed and then rotated for one minute. Visible agglutination is indicative of a positive result, and corresponds roughly to a titer of 1:20. Positive results can be further titrated using the tube method, which is more labour-intensive. Tube method[edit] Using 0.25% phenol saline as a diluent, a series of tubes containing twofold dilutions of patient serum are made with a final volume of 1 mL. A drop of antigen suspension is added to each tube, and the mixture is incubated at 50–55 °C for 4–6 hours. A positive tube would show visible flocculation or granulation, which is accentuated when the tube is gently agitated. The titer corresponds to the most dilute tube in the series that still shows positivity. Generally, a titer of ≥1:320 is considered diagnostic. Subscribe https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw Watch Again https://youtu.be/ggoKUiEPKE0 -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Wald's Visual Cycle - Phototransduction Nerve Impulse Generation
 
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LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN Visual phototransduction is a process by which light is converted into electrical signals in the rod cells, cone cells and photosensitive ganglion cells of the retina of the eye. The visual cycle is the biological conversion of a photon into an electrical signal in the retina. This process occurs via G-protein coupled receptors called opsins which contain the chromophore 11-cis retinal. 11-cis retinal is covalently linked to the opsin receptor via Schiff base forming retinylidene protein. When struck by a photon, 11-cis retinal undergoes photoisomerization to all-trans retinal which changes the conformation of the opsin GPCR leading to signal transduction cascades which causes closure of cyclic GMP-gated cation channel, and hyperpolarization of the photoreceptor cell. A light photon interacts with the retinal in a photoreceptor cell. The retinal undergoes isomerisation, changing from the 11-cis to all-trans configuration Retinal no longer fits into the opsin binding site. Opsin therefore undergoes a conformational change to metarhodopsin II. Metarhodopsin II is unstable and splits, yielding opsin and all-trans retinal. The opsin activates the regulatory protein transducin. This causes transducin to dissociate from its bound GDP, and bind GTP, then the alpha subunit of transducin dissociates from the beta and gamma subunits, with the GTP still bound to the alpha subunit. The alpha subunit-GTP complex activates phosphodiesterase or PDE. PDE breaks down cGMP to 5'-GMP. This lowers the concentration of cGMP and therefore the sodium channels close. Closure of the sodium channels causes hyperpolarization of the cell due to the ongoing efflux of potassium ions. Hyperpolarization of the cell causes voltage-gated calcium channels to close. As the calcium level in the photoreceptor cell drops, the amount of the neurotransmitter glutamate that is released by the cell also drops. This is because calcium is required for the glutamate-containing vesicles to fuse with cell membrane and release their contents. A decrease in the amount of glutamate released by the photoreceptors causes depolarization of On center bipolar cells (rod and cone On bipolar cells) and hyperpolarization of cone off-center bipolar cells. Wikipedia : http://en.wikipedia.org/wiki/Visual_phototransduction -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Nose Anatomy- Nasal Blood Supply
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied LIKE US ON FACEBOOK : fb.me/Medsimplified Follow on Instagram for the Flashcards : https://www.instagram.com/medsimplified/ the nose and sinuses are supplied by the internal carotid artery facial and internal maxillary branches of the. the superior part of the nose receives the anterior and posterior ethmoidal arteries - branches of the ophthalmic artery which itself, is a branch of the internal carotid. the rest of the nose and sinuses is supplied by the greater palatine, sphenopalatine, and superior labial arteries, all of which are branches of the maxillary artery which itself, is a branch of the external carotid. significantly there is a plexus of vessels on the anterior septum - Little's area or Kiesselbach's plexus - where branches of both the internal and external carotid artery anastamose; this is a frequent site for epistaxis. venous drainage of the nose and sinuses is via the ophthalmic and facial veins, and the pterygoid and pharyngeal plexuses. Significantly, drainage is such that infection may spread via the veins to the cavernous sinus. The fleshy external end of the nasal septum is sometimes also called columella. The nasal septum contains bone and hyaline cartilage.[2] The nasal septum is composed of five structures: perpendicular plate of ethmoid bone vomer bone cartilage of the septum crest of the maxillary bone crest of the palatine bone. -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Clotting Factors  - Coagulation Cascade
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied Clotting Factors - Coagulation Cascade 2ND VIDEO - https://www.youtube.com/watch?v=LVYmV5mK6QI LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN There are 13 blood clotting proteins (coagulation factor) found in the blood. They are designated by Roman Numerals I through XIII. When a blood vessel is damaged, these clotting factors are switched on in a certain order (Blood Clotting Cascade) [link to coagulation page] and work to form a clot. Specifically, these 13 factors normally combine to a clot. If one factor is missing or present at low levels, this causes hemophilia and other blood clotting problems and a proper clot will not form. The two most common factor deficiencies are: factor 8 (or factor VIII) deficiency and factor 9 (or factor IX) deficiency. The most common, affecting 80% of the hemophilia population - those with hemophilia A - is factor VIII. When these blood clotting proteins aren't present is not easily stopped. This factor is so important to the treatment of hemophilia, that instead of saying they have "hemophilia A or B," most people say they are "Factor VIII" or "Factor IX" to identify their condition. Various substances are required for the proper functioning of the coagulation cascade: Calcium and phospholipid (a platelet membrane constituent) are required for the tenase and prothrombinase complexes to function. Calcium mediates the binding of the complexes via the terminal gamma-carboxy residues on FXa and FIXa to the phospholipid surfaces expressed by platelets, as well as procoagulant microparticles or microvesicles shed from them. Calcium is also required at other points in the coagulation cascade. Vitamin K is an essential factor to a hepatic gamma-glutamyl carboxylase that adds a carboxyl group to glutamic acid residues on factors II, VII, IX and X, as well as Protein S, Protein C and Protein Z. In adding the gamma-carboxyl group to glutamate residues on the immature clotting factors Vitamin K is itself oxidized. Another enzyme, Vitamin K epoxide reductase, (VKORC) reduces vitamin K back to its active form. Vitamin K epoxide reductase is pharmacologically important as a target of anticoagulant drugs warfarin and related coumarins such as acenocoumarol, phenprocoumon, and dicumarol. These drugs create a deficiency of reduced vitamin K by blocking VKORC, thereby inhibiting maturation of clotting factors. Vitamin K deficiency from other causes (e.g., in malabsorption) or impaired vitamin K metabolism in disease (e.g., in liver failure) lead to the formation of PIVKAs (proteins formed in vitamin K absence) which are partially or totally non-gamma carboxylated, affecting the coagulation factors' ability to bind to phospholipid. Tissue factor pathway (extrinsic)[edit] The main role of the tissue factor pathway is to generate a "thrombin burst", a process by which thrombin, the most important constituent of the coagulation cascade in terms of its feedback activation roles, is released very rapidly. FVIIa circulates in a higher amount than any other activated coagulation factor. The process includes the following steps:[7] Following damage to the blood vessel, FVII leaves the circulation and comes into contact with tissue factor (TF) expressed on tissue-factor-bearing cells (stromal fibroblasts and leukocytes), forming an activated complex (TF-FVIIa). TF-FVIIa activates FIX and FX. FVII is itself activated by thrombin, FXIa, FXII and FXa. The activation of FX (to form FXa) by TF-FVIIa is almost immediately inhibited by tissue factor pathway inhibitor (TFPI). FXa and its co-factor FVa form the prothrombinase complex, which activates prothrombin to thrombin. Thrombin then activates other components of the coagulation cascade, including FV and FVIII (which activates FXI, which, in turn, activates FIX), and activates and releases FVIII from being bound wATCH AGAIN https://www.youtube.com/watch?v=R1wYycfGFjU SUBSCRIBE https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Transcription Made Easy- From DNA to RNA (2018)
 
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Transcription Made Easy- From DNA to RNA (2018) DNA TRANSLATION : https://m.youtube.com/watch?v=QcBYTA7uVXk&t=49s DNA REPLICATION: https://goo.gl/PHJBkz DNA STRUCTURE : https://goo.gl/D6cNoM Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA (especially mRNA) by the enzyme RNA polymerase. Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. Transcription proceeds in the following general steps: RNA polymerase, together with one or more general transcription factors, binds to promoter DNA. RNA polymerase creates a transcription bubble, which separates the two strands of the DNA helix. This is done by breaking the hydrogen bonds between complementary DNA nucleotides. RNA polymerase adds RNA nucleotides (which are complementary to the nucleotides of one DNA strand). RNA sugar-phosphate backbone forms with assistance from RNA polymerase to form an RNA strand. Hydrogen bonds of the RNA–DNA helix break, freeing the newly synthesized RNA strand. If the cell has a nucleus, the RNA may be further processed. This may include polyadenylation, capping, and splicing. The RNA may remain in the nucleus or exit to the cytoplasm through the nuclear pore complex. Transcription of a gene takes place in three stages: initiation, elongation, and termination. Here, we will briefly see how these steps happen in bacteria. You can learn more about the details of each stage (and about how eukaryotic transcription is different) in the stages of transcription article. Initiation. RNA polymerase binds to a sequence of DNA called the promoter, found near the beginning of a gene. Each gene (or group of co-transcribed genes, in bacteria) has its own promoter. Once bound, RNA polymerase separates the DNA strands, providing the single-stranded template needed for transcription. Elongation. One strand of DNA, the template strand, acts as a template for RNA polymerase. As it "reads" this template one base at a time, the polymerase builds an RNA molecule out of complementary nucleotides, making a chain that grows from 5' to 3'. The RNA transcript carries the same information as the non-template (coding) strand of DNA, but it contains the base uracil (U) instead of thymine (T). Termination. Sequences called terminators signal that the RNA transcript is complete. Once they are transcribed, they cause the transcript to be released from the RNA polymerase Eukaryotic pre-mRNAs must have their ends modified, by addition of a 5' cap (at the beginning) and 3' poly-A tail (at the end). Many eukaryotic pre-mRNAs undergo splicing. In this process, parts of the pre-mRNA (called introns) are chopped out, and the remaining pieces (called exons) are stuck back together.
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DNA Replication Made Easy
 
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DNA Replication Made Easy Watch part 2 here : https://youtu.be/Dc21ml8-_PI DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. This process occurs in all living organisms and is the basis for biological inheritance. The cell possesses the distinctive property of division, which makes replication of DNA essential. DNA is made up of a double helix of two complementary strands. During replication, these strands are separated. Each strand of the original DNA molecule then serves as a template for the production of its counterpart, a process referred to as semiconservative replication. Cellular proofreading and error-checking mechanisms ensure near perfect fidelity for DNA replication. In a cell, DNA replication begins at specific locations, or origins of replication, in the genome.[3] Unwinding of DNA at the origin and synthesis of new strands results in replication forks growing bi-directionally from the origin. A number of proteins are associated with the replication fork to help in the initiation and continuation of DNA synthesis. Most prominently, DNA polymerase synthesizes the new strands by adding nucleotides that complement each (template) strand. DNA replication occurs during the S-stage of interphase. DNA replication, like all biological polymerization processes, proceeds in three enzymatically catalyzed and coordinated steps: initiation, elongation and termination. Replication fork Many enzymes are involved in the DNA replication fork. The replication fork is a structure that forms within the nucleus during DNA replication. It is created by helicases, which break the hydrogen bonds holding the two DNA strands together. The resulting structure has two branching "prongs", each one made up of a single strand of DNA. These two strands serve as the template for the leading and lagging strands, which will be created as DNA polymerase matches complementary nucleotides to the templates; the templates may be properly referred to as the leading strand template and the lagging strand template. Watch Again : https://youtu.be/ePZc-71PT_4
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DNA- Structure and function of Deoxyribonucleic Acid (DNA)
 
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DNA- Structure and function of Deoxyribonucleic Acid (DNA) NUCLEIC ACIDS VIDEO : https://youtu.be/0lZRAShqft0 DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA). The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences. DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder. An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell. wATCH AGAIN : https://youtu.be/RA9n0Enu5Gw
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Krebs Cylcle Trick  How to remember krebs cycle FOREVER!!
 
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The Krebs cycle : https://youtu.be/ubzw64PQPqM (called after Hans Krebs) is a part of cellular respiration. Its other names are the citric acid cycle, and the tricarboxylic acid cycle (TCA cycle). Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied It is the series of chemical reactions used by all aerobic organisms to generate energy. It is important to many biochemical pathways. This suggests that it was one of the earliest parts of cellular metabolism to evolve. The Krebs cycle comes after the link reaction and provides the hydrogen and electrons needed for the electron transport chain. It takes place inside mitochondria. The TCA cycle plays a central role in the breakdown, or catabolism, of organic fuel molecules—i.e., glucose and some other sugars, fatty acids, and some amino acids. Before these rather large molecules can enter the TCA cycle they must be degraded into a two-carbon compound called acetyl coenzyme A (acetyl CoA). Once fed into the TCA cycle, acetyl CoA is converted into carbon dioxide and energy. The TCA cycle consists of eight steps catalyzed by eight different enzymes (see Figure). The cycle is initiated when acetyl CoA reacts with the compound oxaloacetate to form citrate and to release coenzyme A (CoA-SH). Then, in a succession of reactions, (2) citrate is rearranged to form isocitrate; isocitrate loses a molecule of carbon dioxide and then undergoes oxidation to form alpha-ketoglutarate; alpha-ketoglutarate loses a molecule of carbon dioxide and is oxidized to form succinyl CoA; succinyl CoA is enzymatically converted to succinate; succinate is oxidized to fumarate; fumarate is hydrated to produce malate; and, to end the cycle, malate is oxidized to oxaloacetate. Each complete turn of the cycle results in the regeneration of oxaloacetate and the formation of two molecules of carbon dioxide. Energy is produced in a number of steps in this cycle of reactions. In step 5, one molecule of adenosine triphosphate (ATP), the molecule that powers most cellular functions, is produced. Most of the energy obtained from the TCA cycle, however, is captured by the compounds nicotinamide adenine dinucleotide (NAD+) and flavin adenine dinucleotide (FAD) and converted later to ATP. Energy transfers occur through the relay of electrons from one substance to another, a process carried out through the chemical reactions known as oxidation and reduction, or redox reactions. (Oxidation involves the loss of electrons from a substance and reduction the addition of electrons.) For each turn of the TCA cycle, three molecules of NAD+ are reduced to NADH and one molecule of FAD is reduced to FADH2. These molecules then transfer their energy to the electron transport chain, a pathway that is part of the third stage of cellular respiration. The electron transport chain in turn releases energy so that it can be converted to ATP through the process of oxidative phosphorylation. The German-born British biochemist Sir Hans Adolf Krebs proposed this cycle, which he called the citric acid cycle, in 1937. For his work he received the 1953 Nobel Prize in Physiology or Medicine. Although Krebs elucidated most of the reactions in this pathway, there were some gaps in his design. The discovery of coenzyme A in 1945 by Fritz Lipmann and Nathan Kaplan allowed researchers to work out the cycle of reactions as it is known today.
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Vestibulocochlear Nerve Anatomy SIMPLIFIED
 
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Vestibulocochlear Nerve Anatomy LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN In this video we will study the simplified version of the Vestibulocochlear nerve or the 8th cranial nerve. The vestibulocochlear nerve consists mostly of bipolar neurons and splits into two large divisions: the cochlear nerve and the vestibular nerve. The cochlear nerve travels away from the cochlea of the inner ear where it starts as the spiral ganglia. Processes from the organ of Corti conduct afferent transmission to the spiral ganglia. It is the inner hair cells of the organ of Corti that are responsible for activation of afferent receptors in response to pressure waves reaching the basilar membrane through the transduction of sound. The exact mechanism by which sound is transmitted by the neurons of the cochlear nerve is uncertain; the two competing theories are place theory and temporal theory. The vestibular nerve travels from the vestibular system of the inner ear. The vestibular ganglion houses the cell bodies of the bipolar neurons and extends processes to five sensory organs. Three of these are the cristae located in the ampullae of the semicircular canals. Hair cells of the cristae activate afferent receptors in response to rotational acceleration. The other two sensory organs supplied by the vestibular neurons are the maculae of the saccule and utricle. Hair cells of the maculae in the utricle activate afferent receptors in response to linear acceleration while hair cells of the maculae in the saccule respond to vertically directed linear force. This is the nerve along which the sensory cells (the hair cells) of the inner ear transmit information to the brain. It consists of the cochlear nerve, carrying information about hearing, and the vestibular nerve, carrying information about balance. It emerges from the pontomedullary junction and exits the inner skull via the internal acoustic meatus (or internal auditory meatus) in the temporal bone. -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Nucleic acids - DNA and RNA structure
 
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Nucleic acids DNA and RNA structure LIKE US ON FACEBOOK : https://fb.me/Medsimplified Nucleic acids are biopolymers, or small biomolecules, essential to all known forms of life. They are composed of monomers, which are nucleotides made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. If the sugar is a simple ribose, the polymer is RNA (ribonucleic acid); if the sugar is derived from ribose as deoxyribose, the polymer is DNA (deoxyribonucleic acid). Nucleic acids are the most important of all biomolecules. They are found in abundance in all living things, where they function to create and encode and then store information in the nucleus of every living cell of every life-form organism on Earth. In turn, they function to transmit and express that information inside and outside the cell nucleus—to the interior operations of the cell and ultimately to the next generation of each living organism. The encoded information is contained and conveyed via the nucleic acid sequence, which provides the 'ladder-step' ordering of nucleotides within the molecules of RNA and DNA. Strings of nucleotides are bonded to form helical backbones—typically, one for RNA, two for DNA—and assembled into chains of base-pairs selected from the five primary, or canonical, nucleobases, which are: adenine, cytosine, guanine, thymine, and uracil; note, thymine occurs only in DNA and uracil only in RNA. Using amino acids and the process known as protein synthesis,[3] the specific sequencing in DNA of these nucleobase-pairs enables storing and transmitting coded instructions as genes. In RNA, base-pair sequencing provides for manufacturing new proteins that determine the frames and parts and most chemical processes of all life forms. One DNA or RNA molecule differs from another primarily in the sequence of nucleotides. Nucleotide sequences are of great importance in biology since they carry the ultimate instructions that encode all biological molecules, molecular assemblies, subcellular and cellular structures, organs, and organisms, and directly enable cognition, memory, and behavior (See: Genetics). Enormous efforts have gone into the development of experimental methods to determine the nucleotide sequence of biological DNA and RNA molecules,[26][27] and today hundreds of millions of nucleotides are sequenced daily at genome centers and smaller laboratories worldwide Watch Again : https://youtu.be/0lZRAShqft0
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Electron Transport Chain ETC Part 2
 
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Electron Transport Chain ETC Made Easy part 2 Watch Part 1: https://www.youtube.com/watch?v=C8VHyezOJD4 LIKE US ON FACEBOOK : https://fb.me/Medsimplified GLYCOLYSIS : https://www.youtube.com/watch?v=8qij1m7XUhk KREBS CYCLE : https://www.youtube.com/watch?v=ubzw64PQPqM&t=181s Beta oxidation: https://www.youtube.com/watch?v=__jS-pjzb5k&t=5s An electron transport chain (ETC) is a series of complexes that transfer electrons from electron donors to electron acceptors via redox (both reduction and oxidation occurring simultaneously) reactions, and couples this electron transfer with the transfer of protons (H+ ions) across a membrane. This creates an electrochemical proton gradient that drives the synthesis of adenosine triphosphate (ATP), a molecule that stores energy chemically in the form of highly strained bonds. The molecules of the chain include peptides, enzymes (which are proteins or protein complexes), and others. The final acceptor of electrons in the electron transport chain during aerobic respiration is molecular oxygen although a variety of acceptors other than oxygen such as sulfate exist in anaerobic respiration. In chloroplasts, light drives the conversion of water to oxygen and NADP+ to NADPH with transfer of H+ ions across chloroplast membranes. In mitochondria, it is the conversion of oxygen to water, NADH to NAD+ and succinate to fumarate that are required to generate the proton gradient. Complex I In Complex I (NADH:ubiquinone oxidoreductase, NADH-CoQ reductase, or NADH dehydrogenase; EC 1.6.5.3), two electrons are removed from NADH and ultimately transferred to a lipid-soluble carrier, ubiquinone (Q). The reduced product, ubiquinol (QH2), freely diffuses within the membrane, and Complex I translocates four protons (H+) across the membrane, thus producing a proton gradient. Complex I is one of the main sites at which premature electron leakage to oxygen occurs, thus being one of the main sites of production of superoxide. The pathway of electrons is as follows: NADH is oxidized to NAD+, by reducing Flavin mononucleotide to FMNH2 in one two-electron step. FMNH2 is then oxidized in two one-electron steps, through a semiquinone intermediate. Each electron thus transfers from the FMNH2 to an Fe-S cluster, from the Fe-S cluster to ubiquinone (Q). Transfer of the first electron results in the free-radical (semiquinone) form of Q, and transfer of the second electron reduces the semiquinone form to the ubiquinol form, QH2. During this process, four protons are translocated from the mitochondrial matrix to the intermembrane space. [4] As the electrons become continuously oxidized and reduced throughout the complex an electron current is produced along the 180 Angstrom width of the complex within the membrane. This current powers the active transport of four protons to the intermembrane space per two electrons from NADH. Complex II In Complex II (succinate dehydrogenase or succinate-CoQ reductase; EC 1.3.5.1) additional electrons are delivered into the quinone pool (Q) originating from succinate and transferred (via flavin adenine dinucleotide (FAD)) to Q. Complex II consists of four protein subunits: succinate dehydrogenase, (SDHA); succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial, (SDHB); succinate dehydrogenase complex subunit C, (SDHC) and succinate dehydrogenase complex, subunit D, (SDHD). Other electron donors (e.g., fatty acids and glycerol 3-phosphate) also direct electrons into Q (via FAD). Complex 2 is a parallel electron transport pathway to complex 1, but unlike complex 1, no protons are transported to the intermembrane space in this pathway. Therefore, the pathway through complex 2 contributes less energy to the overall electron transport chain process. Complex III In Complex III (cytochrome bc1 complex or CoQH2-cytochrome c reductase; EC 1.10.2.2), the Q-cycle contributes to the proton gradient by an asymmetric absorption/release of protons. Two electrons are removed from QH2 at the QO site and sequentially transferred to two molecules of cytochrome c, a water-soluble electron carrier located within the intermembrane space. The two other electrons sequentially pass across the protein to the Qi site where the quinone part of ubiquinone is reduced to quinol. A proton gradient is formed by one quinol (2H+2e-) oxidations at the Qo site to form one quinone (2H+2e-) at the Qi site. (in total four protons are translocated: two protons reduce quinone to quinol and two protons are released from two ubiquinol molecules). QH2 + 2 cytochrome c (FeIII) + 2 H+in → Q + 2 cytochrome c (FeII) + 4 H+out When electron transfer is reduced (by a high membrane potential or respiratory inhibitors such as antimycin A), Complex III may leak electrons to molecular oxygen, resulting in superoxide formation. -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Beta Oxidation of Fatty acids Made Simple- Part 2
 
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Beta Oxidation of Fatty acids Part 1 https://www.youtube.com/watch?v=__jS-pjzb5k Follow on FaceBook : https://goo.gl/syceUO In biochemistry and metabolism, beta-oxidation is the catabolic process by which fatty acid molecules are broken down[1] in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA, which enters the citric acid cycle, and NADH and FADH2, which are co-enzymes used in the electron transport chain. It is named as such because the beta carbon of the fatty acid undergoes oxidation to a carbonyl group. Beta-oxidation is primarily facilitated by the mitochondrial trifunctional protein, an enzyme complex associated with the inner mitochondrial membrane, although some fatty acids are oxidized in peroxisomes. Fatty acid catabolism consists of: Activation and membrane transport of free fatty acids by binding to coenzyme A. Oxidation of the beta carbon to a carbonyl group. Cleavage of two-carbon segments resulting in acetyl-CoA. Oxidation of acetyl-CoA to carbon dioxide in the citric acid cycle. Electron transfer from electron carriers to the electron transport chain in oxidative phosphorylation. -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Addisons Disease Made Simple - Primary Adrenal Faliure
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied .. Addisons Disease Made Simple LIKE US ON FACEBOOK : fb.me/Medsimplified Please SUPPORT MEDSIMPLIFEID BY BUYING ANYTHINGFROM AMAZON OR FLIPKART USING OUR AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN Addison’s disease, also known as primary adrenal insufficiency, is a long-term endocrine disorder in which the adrenal glands do not produce enough steroid hormones.[1] Symptoms generally come on slowly and may include abdominal pain, weakness, and weight loss. Darkening of the skin in certain areas may also occur. Under certain circumstances, an adrenal crisis may occur with low blood pressure, vomiting, lower back pain, and loss of consciousness. An adrenal crisis can be triggered by stress, such as from an injury, surgery, or infection.[1] Addison's disease arises from problems with the adrenal gland such that not enough of the steroid hormone cortisol and possibly aldosterone are produced,[1] most often due to damage by the body's own immune system in the developed world and tuberculosis in the developing world.[2] Other causes include certain medications, sepsis, and bleeding into both adrenal glands.[1][2] Secondary adrenal insufficiency is caused by not enough adrenocorticotropic hormone (ACTH) (produced by the pituitary gland) or CRH (produced by the hypothalamus). Despite this distinction, adrenal crises can happen in all forms of adrenal insufficiency. Addison's disease is generally diagnosed by blood tests, urine tests, and medical imaging.[1] Treatment involves replacing the absent hormones.[1] This involves taking a corticosteroid such as hydrocortisone and fludrocortisone.[1][3] These medications are usually taken by mouth.[1] Lifelong, continuous steroid replacement therapy is required, with regular follow-up treatment and monitoring for other health problems.[4] A high-salt diet may also be useful in some people. If symptoms worsen, an injection of corticosteroid is recommended and people should carry a dose with them. Often, large amounts of intravenous fluids with the sugar dextrose are also required. Without treatment, an adrenal crisis can result in death The signs and symptoms include fatigue; lightheadedness upon standing or difficulty standing, muscle weakness, fever, weight loss, anxiety, nausea, vomiting, diarrhea, headache, sweating, changes in mood or personality, and joint and muscle pains. Some patients have cravings for salt or salty foods due to the loss of sodium through their urine.[8] Hyperpigmentation of the skin may be seen, particularly when the patient lives in a sunny area, as well as darkening of the palmar crease, sites of friction, recent scars, the vermilion border of the lips, and genital skin.[9] These skin changes are not encountered in secondary and tertiary hypoadrenalism.[10] On physical examination, these clinical signs may be noticed:[8] Low blood pressure with or without orthostatic hypotension (blood pressure that decreases with standing) Darkening (hyperpigmentation) of the skin, including areas not exposed to the sun. Characteristic sites of darkening are skin creases (e.g. of the hands), nipple, and the inside of the cheek (buccal mucosa); also, old scars may darken. This occurs because melanocyte-stimulating hormone (MSH) and ACTH share the same precursor molecule, pro-opiomelanocortin (POMC). After production in the anterior pituitary gland, POMC gets cleaved into gamma-MSH, ACTH, and beta-lipotropin. The subunit ACTH undergoes further cleavage to produce alpha-MSH, the most important MSH for skin pigmentation. In secondary and tertiary forms of adrenal insufficiency, skin darkening does not occur, as ACTH is not overproduced. Watch Again https://youtu.be/CjBD0IiRqEE sUBSCRIBE : https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Dna Replication Part 2
 
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Watch part 1 here : https://youtu.be/ePZc-71PT_4 Dna Replication Part 2 DNA is made up of a double helix of two complementary strands. During replication, these strands are separated. Each strand of the original DNA molecule then serves as a template for the production of its counterpart, a process referred to as semiconservative replication. Cellular proofreading and error-checking mechanisms ensure near perfect fidelity for DNA replication. In a cell, DNA replication begins at specific locations, or origins of replication, in the genome. Unwinding of DNA at the origin and synthesis of new strands, accommodated by an enzyme known as ligase, results in replication forks growing bi-directionally from the origin. A number of proteins are associated with the replication fork to help in the initiation and continuation of DNA synthesis. Most prominently, DNA polymerase synthesizes the new strands by adding nucleotides that complement each (template) strand. DNA replication occurs during the S-stage of interphase. DNA polymerases are a family of enzymes that carry out all forms of DNA replication. DNA polymerases in general cannot initiate synthesis of new strands, but can only extend an existing DNA or RNA strand paired with a template strand. To begin synthesis, a short fragment of RNA, called a primer, must be created and paired with the template DNA strand. DNA polymerase adds a new strand of DNA by extending the 3' end of an existing nucleotide chain, adding new nucleotides matched to the template strand one at a time via the creation of phosphodiester bonds. The energy for this process of DNA polymerization comes from hydrolysis of the high-energy phosphate (phosphoanhydride) bonds between the three phosphates attached to each unincorporated base. Free bases with their attached phosphate groups are called nucleotides; in particular, bases with three attached phosphate groups are called nucleoside triphosphates. When a nucleotide is being added to a growing DNA strand, the formation of a phosphodiester bond between the proximal phosphate of the nucleotide to the growing chain is accompanied by hydrolysis of a high-energy phosphate bond with release of the two distal phosphates as a pyrophosphate. Enzymatic hydrolysis of the resulting pyrophosphate into inorganic phosphate consumes a second high-energy phosphate bond and renders the reaction effectively irreversible. DNA replication, like all biological polymerization processes, proceeds in three enzymatically catalyzed and coordinated steps: initiation, elongation and termination. The replication fork is a structure that forms within the nucleus during DNA replication. It is created by helicases, which break the hydrogen bonds holding the two DNA strands together. The resulting structure has two branching "prongs", each one made up of a single strand of DNA. These two strands serve as the template for the leading and lagging strands, which will be created as DNA polymerase matches complementary nucleotides to the templates; the templates may be properly referred to as the leading strand template and the lagging strand template. DNA is always synthesized in the 5' to 3' direction. Since the leading and lagging strand templates are oriented in opposite directions at the replication fork, a major issue is how to achieve synthesis of nascent (new) lagging strand DNA, whose direction of synthesis is opposite to the direction of the growing replication fork. Within eukaryotes, DNA replication is controlled within the context of the cell cycle. As the cell grows and divides, it progresses through stages in the cell cycle; DNA replication takes place during the S phase (synthesis phase). The progress of the eukaryotic cell through the cycle is controlled by cell cycle checkpoints. Progression through checkpoints is controlled through complex interactions between various proteins, including cyclins and cyclin-dependent kinases. Unlike bacteria, eukaryotic DNA replicates in the confines of the nucleus. The G1/S checkpoint (or restriction checkpoint) regulates whether eukaryotic cells enter the process of DNA replication and subsequent division. Cells that do not proceed through this checkpoint remain in the G0 stage and do not replicate their DNA. Replication of chloroplast and mitochondrial genomes occurs independently of the cell cycle, through the process of D-loop replication. Watch Again: https://youtu.be/Dc21ml8-_PI Subscribe please: https://www.youtube.com/user/zoop321
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Viral Hepatitis Made Simple - Pathology , Clinical features & Classifications
 
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Viral Hepatitis Made Simple - Pathology , Clinical features & Classifications All Refrences from Harrisons Principles of Internal Medicine BUY HERE : https://goo.gl/usmRWX LIKE US ON FACEBOOK : fb.me/Medsimplified Viral hepatitis is liver inflammation due to a viral infection. It may present in acute (recent infection, relatively rapid onset) or chronic forms. The most common causes of viral hepatitis are the five unrelated hepatotropic viruses hepatitis A, hepatitis B, hepatitis C, hepatitis D, and hepatitis E. In addition to the nominal hepatitis viruses, other viruses that can also cause liver inflammation include cytomegalovirus, Epstein–Barr virus, and yellow fever. Up to 1997 there has been also 52 cases of viral hepatitis caused by herpes simplex virus. There is the opportunity to prevent or treat the most common types. Hepatitis A and hepatitis B can be prevented by vaccination. Effective treatments for hepatitis C are available but expensive. Signs and symptoms of acute hepatitis appear quickly. They include: fatigue flu-like symptoms dark urine pale stool abdominal pain loss of appetite unexplained weight loss yellow skin and eyes, which may be signs of jaundice Chronic hepatitis develops slowly, so these signs and symptoms may be too subtle to notice -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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DNA Translation Made Easy
 
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Download Marrow Free : http://marrow.roundsapp.org/install Cells need translation to stay alive, and understanding how it works (so we can shut it down with antibiotics) can save us from bacterial infections. Let's take a closer look at how translation happens, from the first step to the final product. The genetic code In an mRNA, the instructions for building a polypeptide come in groups of three nucleotides called codons. Here are some key features of codons to keep in mind as we move forward: There are 616161 different codons for amino acids Three “stop” codons mark the polypeptide as finished One codon, AUG, is a “start” signal to kick off translation (it also specifies the amino acid methionine) These relationships between mRNA codons and amino acids are known as the genetic code (which you can explore further in the genetic code article). In translation, the codons of an mRNA are read in order (from the 5' end to the 3' end) by molecules called transfer RNAs, or tRNAs. Each tRNA has an anticodon, a set of three nucleotides that binds to a matching mRNA codon through base pairing. The other end of the tRNA carries the amino acid that's specified by the codon. Translation: Beginning, middle, and end A book or movie has three basic parts: a beginning, middle, and end. Translation has pretty much the same three parts, but they have fancier names: initiation, elongation, and termination. Initiation ("beginning"): in this stage, the ribosome gets together with the mRNA and the first tRNA so translation can begin. Elongation ("middle"): in this stage, amino acids are brought to the ribosome by tRNAs and linked together to form a chain. Termination ("end"): in the last stage, the finished polypeptide is released to go and do its job in the cell. Our polypeptide now has all its amino acids—does that mean it's ready to to its job in the cell? Not necessarily. Polypeptides often need some "edits." During and after translation, amino acids may be chemically altered or removed. The new polypeptide will also fold into a distinct 3D structure, and may join with other polypeptides to make a multi-part protein. Many proteins are good at folding on their own, but some need helpers ("chaperones") to keep them from sticking together incorrectly during the complex process of folding. Some proteins also contain special amino acid sequences that direct them to certain parts of the cell. These sequences, often found close to the N- or C-terminus, can be thought of as the protein’s “train ticket” to its final destination. For more about how this works, see the article on protein targeting.
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9 Regions of Abdomen made simple
 
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LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN The abdomen has three layers – skin, superficial fascia and muscle. The abdomen houses important organs in the body. It is an essential area of study for doctors when they are assessing pain and illness in patients. The body of the abdomen when viewed from a frontal view is divided into nine imaginary planes, in both vertical and horizontal directions. The nine regions of the abdomen can help determine specific ailments and are of clinical importance. This article will explain the 9 regions of abdomen, the organs in them as well as the 4 quadrants of abdomen. 9 Regions of Abdomen Three horizontal lines and two vertical lines create nine regions of the abdomen. Below is an image of the regions of the abdomen, which are formed within these planes. “Hypo” refers to “below”, “epi” refers to “above”, “chond” refers to the cartilage of the rib and “gast” is in reference to the stomach. Epigastric region (epigastrium) Left hypochondrium (LHC) Right hypochondrium (RHC) Umbilical region Left lumbar region Right lumbar region Hypogastric region Right iliac fossa (RIF) Left iliac fossa (LIF) Watch more videos https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Respiratory System Made Easy
 
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Respiratory System Made Easy LIKE US ON FACEBOOK : fb.me/Medsimplified Human respiratory system, the system in humans that takes up oxygen and expels carbon dioxide. The respiratory tract conveys air from the mouth and nose to the lungs, where the gases oxygen and carbon dioxide are exchanged between the alveoli and the capillaries. The respiratory tract conveys air from the mouth and nose to the lungs, where the gases oxygen and … The human gas-exchanging organ, the lung, is located in the thorax, where its delicate tissues are protected by the bony and muscular thoracic cage. The lung provides the tissues of the human body with a continuous flow of oxygen and clears the blood of the gaseous waste product, carbon dioxide. Atmospheric air is pumped in and out regularly through a system of pipes, called conducting airways, which join the gas-exchange region with the outside of the body. The airways can be divided into upper and lower airway systems. The transition between the two systems is located where the pathways of the respiratory and digestive systems cross, just at the top of the larynx. The upper airway system comprises the nose and the paranasal cavities (or sinuses), the pharynx (or throat), and partly also the oral cavity, since it may be used for breathing. The lower airway system consists of the larynx, the trachea, the stem bronchi, and all the airways ramifying intensively within the lungs, such as the intrapulmonary bronchi, the bronchioles, and the alveolar ducts. For respiration, the collaboration of other organ systems is clearly essential. The diaphragm, as the main respiratory muscle, and the intercostal muscles of the chest wall play an essential role by generating, under the control of the central nervous system, the pumping action on the lung. The muscles expand and contract the internal space of the thorax, the bony framework of which is formed by the ribs and the thoracic vertebrae. The contribution of the lung and chest wall (ribs and muscles) to respiration is described below in The mechanics of breathing. The blood, as a carrier for the gases, and the circulatory system (i.e., the heart and the blood vessels) are mandatory elements of a working respiratory system (see blood; cardiovascular system). Watch Again: https://youtu.be/zd_e9gtDExM Subscribe: https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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EPILEPSY Made Easy - Types,Classification, and Diagnosis
 
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EPILEPSY Made Easy - Types,Classification, and Diagnosis LIKE US ON FACEBOOK : https://fb.me/Medsimplified. Epilepsy is a group of neurological disorders characterized by epileptic seizures.[10][11] Epileptic seizures are episodes that can vary from brief and nearly undetectable to long periods of vigorous shaking.[1] These episodes can result in physical injuries including occasionally broken bones.[1] In epilepsy, seizures tend to recur and as a rule, have no immediate underlying cause.[10] Isolated seizures that are provoked by a specific cause such as poisoning are not deemed to represent epilepsy.[12] People with epilepsy in some areas of the world experience stigma due to the condition.[1] The cause of most cases of epilepsy is unknown.[1] Some cases occur as the result of brain injury, stroke, brain tumors, infections of the brain, and birth defects, through a process known as epileptogenesis.[1][2][3] Known genetic mutations are directly linked to a small proportion of cases.[4][13] Epileptic seizures are the result of excessive and abnormal nerve cell activity in the cortex of the brain.[12] The diagnosis involves ruling out other conditions that might cause similar symptoms such as fainting and determining if another cause of seizures is present such as alcohol withdrawal or electrolyte problems. This may be partly done by imaging the brain and performing blood tests. Epilepsy can often be confirmed with an electroencephalogram (EEG), but a normal test does not rule out the condition. Epilepsy that occurs as a result of other issues may be preventable. Seizures are controllable with medication in about 70% of cases. Inexpensive options are often available.[1] In those whose seizures do not respond to medication, then surgery, neurostimulation, or dietary changes may be considered Not all cases of epilepsy are lifelong, and many people improve to the point that treatment is no longer needed. Normally brain electrical activity is non-synchronous.[2] Its activity is regulated by various factors both within the neuron and the cellular environment. Factors within the neuron include the type, number and distribution of ion channels, changes to receptors and changes of gene expression.[55] Factors around the neuron include ion concentrations, synaptic plasticity and regulation of transmitter breakdown by glial cells.[55][56] Epilepsy[edit] The exact mechanism of epilepsy is unknown,[57] but a little is known about its cellular and network mechanisms. However, it is unknown under which circumstances the brain shifts into the activity of a seizure with its excessive synchronization. In epilepsy, the resistance of excitatory neurons to fire during this period is decreased.This may occur due to changes in ion channels or inhibitory neurons not functioning properly. This then results in a specific area from which seizures may develop, known as a "seizure focus".Another mechanism of epilepsy may be the up-regulation of excitatory circuits or down-regulation of inhibitory circuits following an injury to the brain. These secondary epilepsies occur through processes known as epileptogenesis. Failure of the blood–brain barrier may also be a causal mechanism as it would allow substances in the blood to enter the brain. -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Neuron ANATOMY and Function simplified Video
 
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Neuron Structure and Function simplified LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN A neuron is an electrically excitable cell that processes and transmits information through electrical and chemical signals. These signals between neurons occur via synapses, specialized connections with other cells. Neurons can connect to each other to form neural networks. Neurons are the core components of the brain and spinal cord of the central nervous system (CNS), and of the ganglia of the peripheral nervous system (PNS). Specialized types of neurons include: sensory neurons which respond to touch, sound, light and all other stimuli affecting the cells of the sensory organs that then send signals to the spinal cord and brain, motor neurons that receive signals from the brain and spinal cord to cause muscle contractions and affect glandular outputs, and interneurons which connect neurons to other neurons within the same region of the brain, or spinal cord in neural networks. A typical neuron consists of a cell body (soma), dendrites, and an axon. The term neurite is used to describe either a dendrite or an axon, particularly in its undifferentiated stage. Dendrites are thin structures that arise from the cell body, often extending for hundreds of micrometres and branching multiple times, giving rise to a complex "dendritic tree". An axon (also called a nerve fiber when myelinated) is a special cellular extension (process) that arises from the cell body at a site called the axon hillock and travels for a distance, as far as 1 meter in humans or even more in other species. Nerve fibers are often bundled into fascicles, and in the peripheral nervous system, bundles of fascicles make up nerves (like strands of wire make up cables). The cell body of a neuron frequently gives rise to multiple dendrites, but never to more than one axon, although the axon may branch hundreds of times before it terminates. At the majority of synapses, signals are sent from the axon of one neuron to a dendrite of another. There are, however, many exceptions to these rules: neurons that lack dendrites, neurons that have no axon, synapses that connect an axon to another axon or a dendrite to another dendrite, etc. All neurons are electrically excitable, maintaining voltage gradients across their membranes by means of metabolically driven ion pumps, which combine with ion channels embedded in the membrane to generate intracellular-versus-extracellular concentration differences of ions such as sodium, potassium, chloride, and calcium. Changes in the cross-membrane voltage can alter the function of voltage-dependent ion channels. If the voltage changes by a large enough amount, an all-or-none electrochemical pulse called an action potential is generated, which travels rapidly along the cell's axon, and activates synaptic connections with other cells when it arrives. In most cases, neurons are generated by special types of stem cells. It is generally believed that neurons do not undergo cell division but recent research in dogs shows that in some instances in the retina they do.[1] Astrocytes are star-shaped glial cells that have also been observed to turn into neurons by virtue of the stem cell characteristic pluripotency. In humans, neurogenesis largely ceases during adulthood; but in two brain areas, the hippocampus and olfactory bulb, there is strong evidence for generation of substantial numbers of new neurons. Watch Again https://youtu.be/R_l7glsLXC0 Subscribe https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Acute kidney Failure Made Easy- Part 1/2
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied . Acute kidney injury (AKI), previously called acute renal failure (ARF), PART 2 ACUTE RENAL FALIURE https://www.youtube.com/watch?v=assqpyCPaC8 LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN Its causes are numerous. Generally it occurs because of damage to the kidney tissue caused by decreased kidney blood flow (kidney ischemia) from any cause (e.g., low blood pressure), exposure to substances harmful to the kidney, an inflammatory process in the kidney, or an obstruction of the urinary tract that impedes the flow of urine. AKI is diagnosed on the basis of characteristic laboratory findings, such as elevated blood urea nitrogen and creatinine, or inability of the kidneys to produce sufficient amounts of urine. AKI may lead to a number of complications, including metabolic acidosis, high potassium levels, uremia, changes in body fluid balance, and effects on other organ systems, including death. People who have experienced AKI may have an increased risk of chronic kidney disease in the future. Management includes treatment of the underlying cause and supportive care, such as renal replacement therapy. Prerenal[edit] File:Prerenal acute kidney injury.webm Video explanation of prerenal acute kidney injury Prerenal causes of AKI ("pre-renal azotemia") are those that decrease effective blood flow to the kidney and cause a decrease in the glomerular filtration rate (GFR). Both kidneys need to be affected as one kidney is still more than adequate for normal kidney function. Notable causes of prerenal AKI include low blood volume (e.g., dehydration), low blood pressure, heart failure (leading to cardiorenal syndrome), liver cirrhosis and local changes to the blood vessels supplying the kidney. The latter include renal artery stenosis, or the narrowing of the renal artery which supplies the kidney with blood, and renal vein thrombosis, which is the formation of a blood clot in the renal vein that drains blood from the kidney. Intrinsic[edit] File:Intrarenal acute kidney injury.webm Video explanation of intrarenal acute kidney injury Intrinsic AKI refers to disease processes which directly damage the kidney itself. Intrinsic AKI can be due to one or more of the kidney's structures including the glomeruli, kidney tubules, or the interstitium. Common causes of each are glomerulonephritis, acute tubular necrosis (ATN), and acute interstitial nephritis (AIN), respectively. Other causes of intrinsic AKI are rhabdomyolysis and tumor lysis syndrome.[8] Postrenal[edit] File:Postrenal acute kidney injury.webm Video explanation of postrenal acute kidney injury Postrenal AKI refers to acute kidney injury caused by disease states downstream of the kidney and most often occurs as a consequence of urinary tract obstruction. This may be related to benign prostatic hyperplasia, kidney stones, obstructed urinary catheter, bladder stones, or cancer of the bladder, ureters, or prostate. Watch Again https://youtu.be/82QDj1PwuCM -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Endocrine System Made simple- Human Endocrinology Overview
 
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Endocrinology Made simple- Human Endocrine System Overview Watch part 2 : https://youtu.be/K1y36Atqi-Y Human endocrine system, group of ductless glands that regulate body processes by secreting chemical substances called hormones. Hormones act on nearby tissues or are carried in the bloodstream to act on specific target organs and distant tissues. Diseases of the endocrine system can result from the oversecretion or undersecretion of hormones or from the inability of target organs or tissues to respond to hormones effectively. Modern endocrinology largely originated in the 20th century, however. Its scientific origin is rooted in the studies of French physiologist Claude Bernard (1813–78), who made the key observation that complex organisms such as humans go to great lengths to preserve the constancy of what he called the “milieu intérieur” (internal environment). Later, American physiologist Walter Bradford Cannon (1871–1945) used the term homeostasis to describe this inner constancy. The endocrine system, in association with the nervous system and the immune system, regulates the body’s internal activities and the body’s interactions with the external environment to preserve the internal environment. This control system permits the prime functions of living organisms—growth, development, and reproduction—to proceed in an orderly, stable fashion; it is exquisitely self-regulating, so that any disruption of the normal internal environment by internal or external events is resisted by powerful countermeasures. When this resistance is overcome, illness ensues. The nature of endocrine regulation Endocrine gland secretion is not a haphazard process; it is subject to precise, intricate control so that its effects may be integrated with those of the nervous system and the immune system. The simplest level of control over endocrine gland secretion resides at the endocrine gland itself. The signal for an endocrine gland to secrete more or less of its hormone is related to the concentration of some substance, either a hormone that influences the function of the gland (a tropic hormone), a biochemical product (e.g., glucose), or a biologically important element (e.g., calcium or potassium). Because each endocrine gland has a rich supply of blood, each gland is able to detect small changes in the concentrations of its regulating substances. Some endocrine glands are controlled by a simple negative feedback mechanism. For example, negative feedback signaling mechanisms in the parathyroid glands (located in the neck) rely on the binding activity of calcium-sensitive receptors that are located on the surface of parathyroid cells. Decreased serum calcium concentrations result in decreased calcium receptor binding activity that stimulates the secretion of parathormone from the parathyroid glands. The increased serum concentration of parathormone stimulates bone resorption (breakdown) to release calcium into the blood and reabsorption of calcium in the kidney to retain calcium in the blood, thereby restoring serum calcium concentrations to normal levels. In contrast, increased serum calcium concentrations result in increased calcium receptor-binding activity and inhibition of parathormone secretion by the parathyroid glands. This allows serum calcium concentrations to decrease to normal levels. Therefore, in people with normal parathyroid glands, serum calcium concentrations are maintained within a very narrow range even in the presence of large changes in calcium intake or excessive losses of calcium from the body. Watch Again : https://youtu.be/NOV0OuYxB7g
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How to Fit a Diaphragm or Rim on a Littman Stethoscope
 
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In this video i Will show you how to fit the diaphragm and rim on a stethoscope. Please be gentle or the diaphragm may get damaged. LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Smart Studying Techniques- 5 Essential Study Tips
 
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Smart Studying Techniques- 5 Essential Study Tips How to study smart? 168. That’s how many hours there are in a week. If you’re a student, you probably feel like this isn’t enough. I know… You have so many assignments to do, projects to work on, and tests to study for. Plus, you have other activities and commitments. And I’m sure you want to have a social life, too. Wouldn’t it be nice if you could study smarter (not harder), get good grades, and lead a balanced life? Of course it would. That’s why I made this video The main aim of education isn’t to get straight A’s. But learning how to learn is a vital life skill. So I spent hours scouring scientific articles and research journals to find the best ways to learn more effectively. I’m a lifelong straight-A student myself, and I’ve since completed my formal education. Over the course of my academic career, I’ve used almost all the tips outlined in this video. , so I can verify that they work.
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Testis and Epididymis -  Male Reproductive Anatomy Part 1
 
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Testis and Epididymis - Male Reproductive Anatomy Part 1 LIKE US ON FACEBOOK : fb.me/Medsimplified BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN Subscribe here - https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw The testis is the male gland important for both reproductive and endocrine functions. Initially, it begins as an undifferentiated gonad in the retroperitoneal area. Transcription of the SRY gene (testis-determining factor region) on the Y chromosome ultimately leads to sex differentiation. Without the SRY gene, the gonad would develop into an ovary. As the fetus develops, the functioning testis produces the male hormone testosterone to allow development of male genitalia. Over the last 3 months of gestation, the testis must course its way down from its original retroperitoneal position to its final destination in the scrotum. During its journey it must pass through the peritoneum, abdominal wall via the inguinal canal, and into the scrotal pouch. The testis is a paired, ovoid male reproductive organ that sits in the scrotum, separated from its mate by a scrotal septum. Described by some as being shaped and sized like a large olive or small plum, the average volume of the adult testis is approximately 25 mL. Typically, it measures 3.5-5 cm in length by 2.5-3 cm in both width by 3cm in depth The tunica vaginalis testis (a remnant of the processus vaginalis) envelopes the testis in a double layer, except at the superior and posterior borders where the spermatic cord and epididymis adhere to the testes. The visceral layer of the tunica vaginalis testis is closely applied to the testis, epididymis, and ductus deferens. On the posterolateral surface of the testis, this layer invests a slit-like recess between the body of the epididymis and the testis that is called the sinus of epididymis.[5] The parietal layer of tunica vaginalis is adjacent to the internal spermatic fascia, is more extensive, and extends superiorly into the distal part of the spermatic cord. Deep to the tunica vaginalis, the tunica albuginea is a tough, fibrous outer covering of the testis. On the posterior surface, it is reflected inwardly to form an incomplete vertical septum called the mediastinum testis. The mediastinum testis extends from the superior to near the inferior portion of the gland. It narrows in width as it travels inferiorly. Anteriorly and laterally, numerous imperfect septa are given off, which radiate to the glands surface and are attached to the tunica albuginea. These divide the interior of the testis into numerous, cone-shaped spaces that have a wide base at the gland’s surface and narrow as they converge to the mediastinum. In these spaces, the numerous lobules of glandular structures (the minute but long and highly coiled seminiferous tubules) are housed. The mediastinum supports the ducts and vessels as they pass to and from the glandular substance. The seminiferous tubules are lined with germ cells that produce sperm and nutrient fluid. These tubules empty their contents into a network of anastomosing ducts, which ultimately empties into the epididymis. he epididymis is a comma shaped, elongated structure composed of a single, fine tubular structure estimated up to 6 meters (approximately 20 feet) in length. This tube highly convoluted and tightly compressed (average size of approximately 5 cm) to the point of appearing solid. Located on the posterior border of the testis, it is composed of 3 parts, including the head (caput), body (corpora), and tail (cauda). The epididymal head overhangs the upper pole of the testis, receives the seminal fluid from the ducts of the testis (which pierce the upper portion of the mediastinum), then allows the passage of the sperm into the distal portion of the epididymis. Due to its length, the epididymal duct allows space for storage and maturation of sperm. Progressively tapering in width, the narrow tail continues as the ductus deferens Subscribe here - https://www.youtube.com/channel/UCOmrniWfKi-uCD6Oh6fqhgw Watch Again : https://youtu.be/ImetvbMXgUA -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Female Reproductive System Made Easy - Organs & Functions
 
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Female Reproductive System Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied LIKE US ON FACEBOOK : fb.me/Medsimplified Please SUPPORT MEDSIMPLIFEID BY BUYING ANYTHINGFROM AMAZON OR FLIPKART USING OUR AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN The female reproductive system (or female genital system) is made up of the internal and external sex organs that function in human reproduction. The female reproductive system is immature at birth and develops to maturity at puberty to be able to produce gametes, and to carry a fetus to full term. The internal sex organs are the uterus and Fallopian tubes, and the ovaries. The uterus or womb accommodates the embryo which develops into the fetus. The uterus also produces vaginal and uterine secretions which help the transit of sperm to the Fallopian tubes. The ovaries produce the ova (egg cells). The external sex organs are also known as the genitals and these are the organs of the vulva including the labia, clitoris and vaginal opening. The vagina is connected to the uterus at the cervix.[1] At certain intervals, the ovaries release an ovum, which passes through the Fallopian tube into the uterus. If, in this transit, it meets with sperm, a single sperm can enter and merge with the egg, fertilizing it. The corresponding equivalent among males is the male reproductive system. Fertilization usually occurs in the Fallopian tubes and marks the beginning of embryogenesis. The zygote will then divide over enough generations of cells to form a blastocyst, which implants itself in the wall of the uterus. This begins the period of gestation and the embryo will continue to develop until full-term. When the fetus has developed enough to survive outside the uterus, the cervix dilates and contractions of the uterus propel the newborn through the birth canal (the vagina). The reproductive tract (or genital tract) is the lumen that starts as a single pathway through the vagina, splitting up into two lumens in the uterus, both of which continue through the Fallopian tubes, and ending at the distal ostia that open into the abdominal cavity. In the absence of fertilization, the ovum will eventually traverse the entire reproductive tract from the fallopian tube until exiting the vagina through menstruation. The reproductive tract can be used for various transluminal procedures such as fertiloscopy, intrauterine insemination and transluminal sterilization. Watch Again : https://youtu.be/ZZEsPUQ1gG4 -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Multiple Sclerosis Made Easy- Pathophysiology,symptoms,Treatment.
 
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Multiple Sclerosis Made Easy- Pathophysiology,symptoms,Treatment. LIKE US ON FACEBOOK : fb.me/Medsimplified Multiple sclerosis (MS) is a demyelinating disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This damage disrupts the ability of parts of the nervous system to communicate, resulting in a range of signs and symptoms, including physical, mental, and sometimes psychiatric problems. Specific symptoms can include double vision, blindness in one eye, muscle weakness, trouble with sensation, or trouble with coordination.MS takes several forms, with new symptoms either occurring in isolated attacks (relapsing forms) or building up over time (progressive forms) Between attacks, symptoms may disappear completely; however, permanent neurological problems often remain, especially as the disease advances While the cause is not clear, the underlying mechanism is thought to be either destruction by the immune system or failure of the myelin-producing cells.Proposed causes for this include genetics and environmental factors such as being triggered by a viral infection.MS is usually diagnosed based on the presenting signs and symptoms and the results of supporting medical tests. There is no known cure for multiple sclerosis.Treatments attempt to improve function after an attack and prevent new attacks. Medications used to treat MS, while modestly effective, can have side effects and be poorly tolerated. Physical therapy can help with people's ability to function.Many people pursue alternative treatments, despite a lack of evidence. The long-term outcome is difficult to predict, with good outcomes more often seen in women, those who develop the disease early in life, those with a relapsing course, and those who initially experienced few attacks Life expectancy is on average 5 to 10 years lower than that of an unaffected population.. Watch Again: https://youtu.be/EnV0w9RxFho -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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Acute Renal Failure Made Easy- Part 2/2
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied . Acute kidney injury (AKI), previously called acute renal failure (ARF), PART1 ACUTE RENAL FALIURE https://www.youtube.com/watch?v=82QDj1PwuCM Follow on FaceBook : https://goo.gl/syceUO BUY USING AFFILIATE LINKS : AMAZON US--- https://goo.gl/XSJtTx AMAZON India http://goo.gl/QsUhku FLIPKART http://fkrt.it/Wiv8RNNNNN FLIPKART MOBILE APP http://fkrt.it/Wiv8RNNNNN Its causes are numerous. Generally it occurs because of damage to the kidney tissue caused by decreased kidney blood flow (kidney ischemia) from any cause (e.g., low blood pressure), exposure to substances harmful to the kidney, an inflammatory process in the kidney, or an obstruction of the urinary tract that impedes the flow of urine. AKI is diagnosed on the basis of characteristic laboratory findings, such as elevated blood urea nitrogen and creatinine, or inability of the kidneys to produce sufficient amounts of urine. AKI may lead to a number of complications, including metabolic acidosis, high potassium levels, uremia, changes in body fluid balance, and effects on other organ systems, including death. People who have experienced AKI may have an increased risk of chronic kidney disease in the future. Management includes treatment of the underlying cause and supportive care, such as renal replacement therapy. Prerenal File:Prerenal acute kidney injury.webm Video explanation of prerenal acute kidney injury Prerenal causes of AKI ("pre-renal azotemia") are those that decrease effective blood flow to the kidney and cause a decrease in the glomerular filtration rate (GFR). Both kidneys need to be affected as one kidney is still more than adequate for normal kidney function. Notable causes of prerenal AKI include low blood volume (e.g., dehydration), low blood pressure, heart failure (leading to cardiorenal syndrome), liver cirrhosis and local changes to the blood vessels supplying the kidney. The latter include renal artery stenosis, or the narrowing of the renal artery which supplies the kidney with blood, and renal vein thrombosis, which is the formation of a blood clot in the renal vein that drains blood from the kidney. Intrinsic[edit] File:Intrarenal acute kidney injury.webm Video explanation of intrarenal acute kidney injury Intrinsic AKI refers to disease processes which directly damage the kidney itself. Intrinsic AKI can be due to one or more of the kidney's structures including the glomeruli, kidney tubules, or the interstitium. Common causes of each are glomerulonephritis, acute tubular necrosis (ATN), and acute interstitial nephritis (AIN), respectively. Other causes of intrinsic AKI are rhabdomyolysis and tumor lysis syndrome.[8] Postrenal File:Postrenal acute kidney injury.webm Video explanation of postrenal acute kidney injury Postrenal AKI refers to acute kidney injury caused by disease states downstream of the kidney and most often occurs as a consequence of urinary tract obstruction. This may be related to benign prostatic hyperplasia, kidney stones, obstructed urinary catheter, bladder stones, or cancer of the bladder, ureters, or prostate. Watch Again https://youtu.be/82QDj1PwuCM -~-~~-~~~-~~-~- CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure " https://www.youtube.com/watch?v=0lZRAShqft0 -~-~~-~~~-~~-~-
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HUMAN DIGESTIVE SYSTEM Made Easy- Gastrointestinal System
 
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Help us Improve our content Support us on Patreon : https://www.patreon.com/medsimplfied LIKE US ON FACEBOOK : fb.me/Medsimplified Human digestive system, the system used in the human body for the process of digestion. The human digestive system consists primarily of the digestive tract, or the series of structures and organs through which food and liquids pass during their processing into forms absorbable into the bloodstream. The system also consists of the structures through which wastes pass in the process of elimination and other organs that contribute juices necessary for the digestive process. The digestive tract begins at the lips and ends at the anus. It consists of the mouth, or oral cavity, with its teeth, for grinding the food, and its tongue, which serves to knead food and mix it with saliva; the throat, or pharynx; the esophagus; the stomach; the small intestine, consisting of the duodenum, the jejunum, and the ileum; and the large intestine, consisting of the cecum, a closed-end sac connecting with the ileum, the ascending colon, the transverse colon, the descending colon, and the sigmoid colon, which terminates in the rectum. Glands contributing digestive juices include the salivary glands, the gastric glands in the stomach lining, the pancreas, and the liver and its adjuncts—the gallbladder and bile ducts. All of these organs and glands contribute to the physical and chemical breaking down of ingested food and to the eventual elimination of nondigestible wastes. Their structures and functions are described step by step in this section. The major parts of the digestive system: Salivary glands. Pharynx. Esophagus. Stomach. Small Intestine. Large Intestine. Rectum. Accessory digestive organs: liver, gallbladder, pancreas. The function of the digestive system is digestion and absorption. Digestion is the breakdown of food into small molecules, which are then absorbed into the body. The digestive system is divided into two major parts: The digestive tract (alimentary canal) is a continuous tube with two openings: the mouth and the anus. After the food is swallowed, it enters the esophagus where it continues to move toward the stomach. The small intestine is the main site of digestion and absorption. There, the pancreas, liver, gallbladder, and the small intestine itself combine juices to break down nutrients so that they can be absorbed.
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