Endocrinology - Insulin

Armondo historian biology and medicine videos please make sure to subscribe join the forum in group for the latest videos please visit Facebook live under a pseudonym and here you can also like please ask questions answer questions and post some interesting things such as your outlooks you can also change the quality settings to the highest one for better graphics let's talk about insulin into is a polypeptide hormone and as I mentioned it has a major role in the regulation of macromolecules within our body and as a major role in the homeostatic condition of metabolism but the main role insulin has is in storing excess energy as in storing fats lipids carbohydrates and proteins such as during a phase state so now I would like to show you the Associated organs insulin has an effect on so for example here we have the intestines hearing of the blood we have the liver skeletal muscle lymphatic circulation adipose tissue and finally the last organ the pancreas now instant has a major effect during the fed state so basically just after we eat because after we eat we would have many macromolecules running through our intestines such as glucose here amino acids and then we also have fats now let's consider in glucose first what happens here well glucose will be absorbed by the blood and the pancreas will secrete insulin and insulin will promote the uptake of glucose from the blood into the liver insulin will also promote the conversion of glucose to glycogen the storage unit of glucose insulin will promote the conversion of glucose to pyruvate and then to a silk away by glycolysis insulin will promote a silk away to transyl glycerols and then transfer glycerols can then be packaged up into very low density lipoproteins which can then be stored as a trance of glycerol in adipose tissue so insulin does all these things initiative also has effective amino acids amino acids will be are absorbed by the blood in turn will call or will promote the uptake of amino acids from the bloodstream to the liver and then in turn will promote our protein approach pursue Genesis therefore promoting protein synthesis insert also has effects on facts but fats are absorbed through the lymphatic circulation up to the blood and insulin will promote our the storage of fats within skeletal muscle up as fatty acids insulin also promote the synthesis of trials or glycerol from fat in the liver so that was a brief overview of the effects insulin has on the different types of organs in our body and as you can see engine has the major role of storing excess energy such as during the fed state when we have a lot of macromolecules running through our intestines that need storing so now let's go get insulin synthesis and insulin synthesis occurs in the pancreas but particularly in the beta cells of the pancreas because it is within these beta cells that insulin is secreted from so let's begin with the ribosome which translates mRNA into a particular protein and this protein is actually for insulin so this protein will form what's called a pre pro insulin which is a long polypeptide and then this pre pro insulin will get transported into the endoplasmic reticulum where it will get sorted out and cleaved up a bit to form pro insulin and the pro insulin consists of three segments a c in the middle and B now this pro insulin will then travel to the Golgi apparatus where we'll get cleaved up into the associated segments the C peptide which is in the middle and also the a and B peptide which will form insulin the a and B peptide will be bounded together by disulfide bonds and this is what insulin is so insulin is connected by disulfide bonds from the a and B peptides from pro insulin and the C peptide will then travel to C peptide has a role in the cell membrane serve four g-protein signaling in some way so that is insulin now can then be secreted into the bloodstream where it will travel to its target tissue or associated organs now for example it will travel to the liver let's just say or it can travel to the skeletal muscle so now let's zoom into the membranes of the skeletal muscle liver so the membranes are obviously different but the insulin receptor is the same because insulin receptor is a tyrannous tyrosine kinase receptor and it consists of two alpha subunits two bitter subunits and tyrosine kinase that in the intracellular fluid in the inside tyrosine kinase is an enzyme and it's inactive when it's not phosphorylated when it doesn't have a phosphate group but usually tertian kinase has Auto phosphorylation which means that it always has a phosphate group so tyrosine kinase when it has a phosphate group coming off it it is active okay now within that with inside the cell in the cytosol in the intracellular fluid there is a target protein with with a tyrosine amino acid for example and this target protein is inactive when it's not phosphorylated so how does it become active and how does the tyrosine kinase receptor the insulin receptor become stimulated well when insulin travels to the target organ for example the liver the two insulins will have to bind to two alpha subunits which will then cause tyrosine kinase to phosphorylate the target protein in the inside of the cell so this target protein will become phosphorylated it will have the phosphate group attached to tyrosine amino acid and now because it stronger protein is phosphorylated it is active and so because it is active it can then cause the intracellular effects of insulin I hope you understood that that was a brief overview but now let's look at it look at this a tyrosine kinase receptor in a bit more detail so let's look at it again in a more bigger picture so here we have the liver will cut a cross-section here and look at one of the cell of the hepatocytes the cell membrane of the hepatocytes so the tyrosine kinase receptor which is for insulin the insulin receptor consists of four subunits and two in inner enzymes so it consists of two alpha subunits tubular subunits and two intracellular tyrosine kinase bound it to the beta subunits on the inner membrane and the tyrosine kinase is auto phosphorylated so it contains many phosphate groups the alpha and beta subunits as well as the alpha and alpha subunits are connected by disulfide bonds once insulin binds to the Alpha subunits there needs to be two insulin binds with alpha subunits it will cause an inner Prout inner membrane protein known as irs-1 to be phosphorylated and this will activate irs-1 which is the target protein irs-1 once phosphorylated has effects on that particular cell such as it will promote growth and for gene expression IRS can also promote glycogen synthesis for storage of glucose irs-1 once phosphide will also promote fat synthesis so the synthesis of trials or glycerols irs-1 will also stimulate protein synthesis once it absorbs the amino acids it will make proteins and also importantly Irish one will increase the expression of glucose transporters what this means is that glucose transporters in the inner membrane will travel out with to the plasma membrane to the outer membrane and in this case the liver has a special glucose transporter called blue 2 now it should be noted here that diabetes or mainly insulin resistance is a condition when insulin itself cannot bind to the tyrosine kinase receptor and therefore IRS cannot increase the expression of glucose transporters and therefore glucose just accumulates in the blood stream increasing blood glucose levels and so liver as I mentioned expresses specifically type 2 glute transporters other organs has different glute transporters like the muscle has glued for anyway the increased expression of glute to transporters will increase the absorption of glucose from the bloodstream into the liver so glucose is inside the liver now and glucose can then be can have can then have a number of fates it can be stored as our glycogen as in glycogen synthesis or it can be converted to fats which will then be packaged up as a vldls very low density lipoproteins or lipoproteins in general and to be exported into the adipose tissue to be as well stored so insulin now let's look at the broad picture here so insolent essentially lowers blood glucose levels as well as store edit as well as it stimulates the absorption and storage of excess energy so let's go let's let's go over some the major effects insulin has in the body so insulin stimula egg inhibits the degradation of glycogen to glucose so it inhibits glycogen phosphorylase the enzyme responsible for this insulin promotes glucose our glucose conversion to glucose 6-phosphate so it stimulates the enzyme hexokinase insulin also stimulates the conversion of glucose 6-phosphate through a number of through a series of enzymes to glycogen and so essentially it stimulates glycogen synthase the enzyme for glycogen synthesis insulin also increases the expression of glucose transporters in the liver so increases our glucose transport to the liver so increases glute to transporters also insulin increases the expression of glute for transporters in the muscle and adipose tissue insulin also stimulates ribosome activity to synthesize proteins so protein synthesis and so it also inhibits particularly protein degradation because it wants to store excess energy you want to store amino acids insulin also promotes the conversion from glucose to a silk away so it promotes glycolysis as well as ensuring promotes fatty acid synthesis from a silicon to transfer glycerol and finally as insulin also inhibits hormone sensitive lipase which is responsible for the degradation of transfer glycerol to fatty acids of course insulin also prevents speed oxidation conversion of fatty acids into a silhouette in summary insulin is important in storing excess energy in the forms of glycogen transfer glycerols and proteins in different organ in different organs and that concludes basically this video on insulin please the video on glucagon if you haven't watched the yet please comment like and subscribe thank you very much

Channel: Armando Hasudungan

Views: 369,244

Rating: 4.9595823 out of 5

Keywords: INSULIN, insulin, resistance, tyrosine, kinase, IRS-1, IRS1, factor, pancreas, beta, cells, effect, summary, overview, endocrine, system, lecture, armandohasudungan, what is insulin, receptor, synthesis of insulin, production, proinsulin, preproinsulin, secretion

Id: 5jWAiE4dhHc

Length: 12min 17sec (737 seconds)

Published: Sun Dec 02 2012