Insulin Flashcards
What cells are found in Pancreatic Islets? (4)
What do they secrete?
Beta cells - insulin
Alpha cells - glucagon
Delta cells - somatostatin
PP cells - pancreatic polypeptide
Where in beta cells is insulin produced?
Rough endoplasmic reticulum
What are the structural stages of insulin production?
Preproinsulin –> proinsulin + single peptide –> insulin + C peptide
What transporter allows glucose into beta cells?
GLUT 2
Describe cellular processes leading up to insulin secretion
Glucose enters cell via GLUT2
Glucose undergoes respiration to make ATP
ATP inhibits Katp channels which causes intracellular build up of K+
Cell becomes depolarised
Ca++ voltage gated channels respond to depolarisation and Ca++ enters cell
Increased cellular Ca++ causes insulin containing vesicles to fuse with cell membrane and secrete
Why are there 2 peaks of insulin secretion?
1st peak is readily available insulin
2nd peak is insulin that needed a preparatory reaction to be mobilised
What affect does Sulphonylurea drug class have on Katp channels?
Inhibits them (acting like ATP would) which causes downstream release of insulin
What affect does Diazoxide drug have on Katp channels?
Stimulates them which prevents insulin release downstream
What is MODY?
Maturity onset diabetes of the young
inherited defect in beta cell function = faulty insulin secretion + impaired glucokinase activity
Treatment for MODY?
Sulphonylurea
Regulatory functions of Insulin besides glucose? (6)
DNA synthesis, lipogenesis, glycogen synthesis
Gene regulation
Inhibits lipolysis and gluconeogenesis
What type of receptor does insulin act on?
Receptor tyrosine kinase
Insulin will function in absence of any adipose tissue. T/F?
False, need a bit of adipose or would cause insulin resistance as and as too much adipose
Presentation of Ketoacidosis
vomiting, tachycardia, smelly breath
What are ketone bodies made from?
Acetyl-CoA when there is a lack of Oxaloacetate meaning it can’t enter TCA cycle
