4- physiology of pancreas Flashcards
what are endocrine secretions in pancreas?
insulin, glucagon & somatostatin →secreted to blood
what are the endocrine cells of the pancreas?
islets of langerhans
what are exocrine secretions of pancreas?
digestive enzymes & aqueous bicarbonate ions (NaHCO3-)
= secreted to duodenum collectively as pancreatic juice
what are exocrine cells in pancreas?
acinar cells & duct cells
- duct cells release bicarbonate and acinar cells release digestive enzymes
what does bicarbonate do and what released it?
duct cells secrete bicarbonate which neutralises acidic chyme entering duodenum
describe action of insulin
dietary intake = increased glucose→pancreatic beta cells →secrete insulin →converts glucose to glycogen
describe action of glucagon
metabolism = decreased glucose →pancreatic alpha cells →secrete glucagon →stimulates glycogen convert to glucose
describe process of secretion of insulin?
elevation of blood glucose →increased diffusion of glucose in beta cell by facilitated transport of GLUT2 →phosphorylation of glucose by glucokinase →glycolysis of glucose-6-phosphate in mitochondria yielding ATP →increased ATP/ADP ratio with cell closes ATP sensitive K+ channels causing membrane depolarisation (as less K+ efflux) →triggers opening of voltage gated calcium channels increases intracellular calcium that triggers insulin secretion
what is type 1 and type 2 diabetes?
type 1 = not sufficient secretion of insulin, earlier in life
type 2 = desensitization to insulin receptors, later in life due to lifestyle choices, also has inappropriate gluconeogenesis (increased glucose)
what are pharmacological treatments of type 2?
- sulfonylureas
- metformin
what is mechanism and example of sulfonoylureas?
example is gliclazide (treatment for type 2 diabetes)
- acts by closing potassium ATP channels and stimulating insulin release
what is mechanism of metformin?
= treatment of type 2 diabetes
- reduces hepatic gluconeogenesis by stimulating AMP-activated protein kinase (AMPK) triggering GLP-1 secretion which enhances insulin release from pancreatic beta cells
what is cortisol?
stress hormone that causes increased gluconeogenesis (increases glucose) to utilised in stress for fight or flight response
what is effect of adrenaline on glucose?
adrenaline stimulates pancreatic alpha cells to secrete glucagon which stimulate glycogen →glucose
what membrane transporters are in pancreatic duct cells?
- sodium carbonate transporter →Na+ in and bicarbonate in to be transported out by chlorine bicarbonate exchanger on apical side to stabilise pH
- sodium potassium pump →SOPI
- sodium proton pump = H+ out and Na+ in
- potassium proton pump = H+ out and K+ in
