1- endocrine pancreas Flashcards
what are cells in islets of langerhans - what do they produce?
alpha cells = glucagon
beta cells = insulin
delta cells = somatostatin
PP cells = pancreatic polypeptide
epsilon cells = ghrelin
what happens with glucose & hormones etc when
a) you eat
b) you fast
a) eat →high glucose →insulin production in liver →glycogenesis (stores glucose so reduces blood glucose)
b) fast →low glucose →glucagon production in liver →lipolysis (make glucose)
what is the state of K+ ATP channel at
a) low glucose level
b) high glucose level
a) it’s open - maintaining hyperpolarized plasma membrane
b) it’s closed - causing depolarisation (less negative) of plasma membrane and stimulating Ca2+ influx which triggers insulin secretion
what type of things do beta cells sense?
nutrients, hormones, neurotransmitters = there’s a lot of factors that help beta cell to secrete appropriate amounts of insulin
how is alpha cell different from beta cell?
has different channels for sensing glucose - works in opposite way (obvious if you think about it)
- high glucose = switch off
- low glucose = switch on (glucose gone get some glucagon)
*glucagon also has complex production as proglucagon can give rise to many different hormones like GLP-1 etc depending how cleaved
what is main effect of glucagon?
increased glucose & increased food intake
= it travels to liver and promotes glycogenolysis
what is exocrine purpose & example?
= make hormones for distant tissue e.g. digestive amylase or lipase for small intestine
what is endocrine purpose and example?
= makes hormones that go in blood & travel everywhere in blood
e.g. insulin & glucagon
what is paracrine purpose & example?
= cell in pancreas talking to neighbour using signals
e.g. delta cell making somatostatin which stops alpha cell making glucagon
what is autocrine purpose & example?
= cell sends signal to itself
e.g. beta cell makes insulin that binds to same beta cell to stop making too much
what is juxtacrine purpose & example?
= 2 cells touch each other to send signals
e.g. beta cells physically connected & keeping in sync
what is delta cell function?
it makes somatostatin which is a hormone that suppresses function of cells around it. delta cell has long shape to allow connection to multiple cells
- it’s controller hormone e.g. it can sense insulin & glucose etc and can damp down effects if they want to
