Pancreatic Beta Cell Flashcards
what is produced by pancreatic beta cells in the pancreatic islets
insulin
what is the first step of insulin secretion
glucose enters beta cell, when conc. increases, via GLUT2 transporter
what happens to glucose in the pancreatic beta cell
it is phosphorylated by glucokinase, to produce glucose-6-phosphate
what does increased metabolism of glucose lead to
increase in intracellular ATP conc.
what does ATP inhibit in the pancreatic beta cell, and what does this lead to
ATP sensitive K+ channel Katp, leads to depolarisation of the cell membrane
what is the result of the depolarisation of the cell membrane of the pancreatic beta cells
opening on the voltage gated Ca2+ channels, increasing intracellular Ca2+ conc.
what does an increase in intracellular Ca2+ conc. lead to
fusion of secretory vesicles with the cell membrane and insulin secretion
what is the amount of insulin released from the pancreatic beta cell directly related to
the amount of glucose that has entered the cell and has been phosphorylated
what level of blood glucose should insulin be produced at
if rises above 5 mM
what happens to pancreatic beta cells in type 1 diabetes
autoimmune attack on them, most are lost and don’t secrete insulin
describe the effect on pancreatic beta cells in forms of diabetes where they are still present
cells lose ability to respond to changes in glucose due to hyperglycaemia glucose conc. outwith the Km of glucokinase
describe the pattern of insulin secretion
biphasic, the first wave to prevent sharp increase in blood increase, the second more tuned to insulin needs
describe why there are 2 phases of insulin secretion
5% of insulin is immediately available - RRP, readily releasable pool
Reserve pool of insulin needs to undergo other reactions/signals to become mobilised
what happens to insulin secretion in poorly controlled T2DM
insulin secretion weakens and flattens, not biphasic
