Flashcards in Insulin Secretion and signalling Deck (22):
Where is insulin made?
What types of cells pancreatic islets and what do they secrete?
beta cells - insulin
alpha cells - glucagon
delta cells - somatostatin
PP cells - pancreatic polypeptide
What is the structure of insulin?
linked by disulfide bonds
connecring (C) peptide
How does glucose enter beta cells?
through GLUT2 transporter
What happens when glucose enters the beta cell?
Phosphorylated by glucokinase
Increases intracellular ATP
ATP inhibits K ATP channel
Voltage gated Ca2+ channels open
Vesicles fuse to membrane
Desribe the two phases of insulin secretion
1st-readily releasable pool
What subunits make up the K ATP channel? What inhibits each subunit?
Kir6.2 pore - ATP
SUR1 regulatory - sulphonylurea
What stimulates the K ATP channel at the SUR1 subunit?
Describe what the defect in MODY
Glucose sensing defect
Increases threshold for insulin secretion
What are the three phases of the signalling cascade?
Reception of hormone
What is the name of the insulin receptor?
Describe the tyrosine kinase receptor
2 alpha subunits
2 beta subunits
Describe what happens in insulin signalling
Insulin binds to alpha subunits
Autophosphorylation at beta subunits
Insulin receptor substrates phosphorylated
Causes gene expression and glycogen synthesis
Describe how glycogen is synthesised
PKB causes GLUT4 to translocate to surface
Glucose into cell
What are the biological processes insulin increases?
What biological processes does insulin prevent?
Gluconeogenesis in liver
What happens in Donohue syndrome (leprachaunism)
What happens in Robson Mendenhall syndrome?
leads to: hyperpigmentatoin
DKA hypoglycaemia respone
Where are ketone bodies produced?
When are ketone bodies formed?
fatty acids oxidised in TCA cycle
excess acetyl co-A turned to ketone bodies
Name three ketone bodies