Insulin Flashcards
what percentage of the pancreas is ‘endocrine’?
1%
what are the patches of endocrine pancreas tissue known as?
islets of langerhans
what are the 4 types of islet cells?
alpha, beta, delta and F
what do alpha islet cells produce?
glucagon
what do beta islet cells produce?
insulin
what do delta islet cells produce?
somatostatin
what is somatostatin also known as?
growth hormone inhibiting hormone
what do F islet cells produce?
pancreatic polypeptide
is insulin a peptide, amine or steroid hormone?
peptide
which pancreatic cells produce insulin?
beta islet cells
what form is insulin first synthesised in?
preproinsulin
where is preproinsulin converted?
ER
what is preproinsulin converted to?
proinsulin
where is proinsulin converted?
within granules in secretory vesicles
what is proinsulin converted to?
insulin and C-peptide
what is the major stimulus for insulin secretion?
blood glucose concentration
insulin is the only hormone which ____________
insulin is the only hormone which lowers [BG]
which receptors does insulin bind to on the target cells?
tyrosine kinase receptors
what effect does insulin binding to tyrosine kinase receptors have?
increases glucose uptake by those cells
which glucose transporter does insulin mobilise in muscle and adipose tissue?
GLUT-4
which types of tissue are insulin dependent?
muscle and fat
where can GLUT-1 transporters be found?
brain, kidney, red blood cells, among others
which glucose transporters do beta cells in the pancreas use?
GLUT-2
is the liver insulin dependent?
no
is the insulin response to an intravenous glucose load more or less than the equivalent amount of glucose administered orally, and why?
less - orally administered glucose increases insulin production by direct effect on beta cells AND vagal stimulation of beta cells, plus incretin effects
which hormone primarily opposes the action of insulin?
glucagon
where does glucagon mainly act?
liver
