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#medicines #drnajeeb #pharmacology #medicaleducation #insulin Insulin Synthesis and Secretion | Part 3/4 Like this video? Sign up now on our website at to access 800 Exclusive videos on Basic Medical Sciences & Clinical Medicine. These are premium videos (NOT FROM YOUTUBE). All these videos come with English subtitles & download options. Sign up now! Get Lifetime Access for a one-time payment of $99 ONLY! Sign up now on our website at #!/register-fast --------------------------------------------------------------------------------------------------------------------------- Why sign up for premium membership? Here's why! Membership Features for premium website members. 1. More than 800 Medical Lectures. 2. Basic Medical Sciences & Clinical Medicine. 3. Mobile-friendly interface with android and iOS apps. 4. English subtitles and new videos every week. 5. Download option for offline video playback. 6. Fanatic customer support and that's 24/7. 7. Fast video playback option to learn faster. 8. Trusted by over 2M students in 190 countries. --------------------------------------------------------------------------------------------------------------------------- (0:00-2:30) Outline: Synthesis, Storage, Release & Regulation of Insulin. Exocrine & Endocrine function. Acinar cells; synthesize digestive enzymes and release into the duodenum. (2:33-10:15) The endocrine function of cells: Islets of Langerhans; scattered within the pancreas comprise 1% of the pancreas, millions in number. Cells, B cells, D cells, F cells/PP cells in a single Islet. B cells in the center of Islets, surrounded by A cell’s outer parts. D cells; are scattered around the Islet. (10:16-15:17) Products produced by different cells. B cells = Insulin; stimulated by glucose intake. C-peptide released in equimolar quantity with insulin. Pro-insulin; biologically inactive form of Insulin. Amylin is found in pancreas of patients of Type 2 Diabetes. (15:20-18:00) A cells; active when blood glucose level is low, will release = Glucagon. Glucagon prevents the rapid fall in blood glucose, can release glucose from liver, adipose tissues. (18:03-20:40) D cells = Somatostatin; Universal Inhibitor; inhibits B cells & A cells. (20:45-25:40) Blood supply to Islets of Langerhans; directly into center where B cells are. Then through fenestrated capillaries supply rest of the cell. After that blood will move into the venules. Blood flow pattern is therefore, from center to the periphery. Insulin moves along the pattern with blood; suppressing A cells on the way. (25:43-30:25) Structure of Precursor of Insulin (Pre-Proinsulin) = Initial segment/Signal sequence, B-chain, A-chain & remaining component connects A and B chain = Connecting peptide/C-chain. (30:28-36:18) When Signal sequence is destroyed; remaining B-chain C-chain A-chain is actually Pro-Insulin. Pro-insulin has disulfide bonds; connecting B-chain with A-chain. When C-segment is cut off; C-peptide is released, only A B chain remains. This is biologically active Insulin. Summary of formation of active Insulin from Pre-proinsulin. (36:19-50:40) Synthesis of Insulin from genetic level; short arm of chromosome no 11, gene for Insulin. Transcription; mRNA in cytoplasm, gets attached with ribosomes; which will translate into Amino Acid sequence of a protein; Signal sequence formation. Signal Sequence is hydrophobic and will take ribosome into Rough Endoplasmic Reticulum (RER); Initial segments will get attached with RER repeatedly in this manner. Ultimately long Initial Sequence is formed inside the RER and pro-insulin formed; released in form of vesicles loaded with Pro-insulin molecules. Arrives in Golgi complex; as proinsulin molecules with disulfide bonds. Endopeptidases in Golgi Complex convert Pre insulin to biologically active Insulin; released as secretory vesicles containing Insulin and C-peptide. In Secretory vesicles, Insulin is stored along with Zinc molecules. (50:45-55:15) Release of Insulin; B cells respond to increased level of glucose in blood; act as Glucose Sensors. Insulin is a major anabolic hormone. A summary of synthesis. --------------------------------------------------------------------------------------------------------------------------- Join this channel to get access to perks: Sign up now on our website at #!/register-fast Follow us on Facebook :- Follow us on Instagram :-
