Pancreatic Hormone Physioloy Flashcards
Which hormones do Alpha pancreatic cells release?
Glucagon
Proglucagon
Which hormones do Beta pancreatic cells release?
Insulin C-peptide Proinsulin Islet amyloid polypeptide GABA
Which hormones do Delta pancreatic cells release?
Somatostatin
Which hormones do Epsilon pancreatic cells release?
Ghrelin
Which hormones do F or PP pancreatic cells release?
Pancreatic polypeptide.
What are the steps in insulin secretion/creation?
Insulin gene translated into preproinsilin in ER where it will be cleaved into proinsulin.
Proinsilin is packaged into secretory vesicles with C-peptide.
A mature insulin vesicle contains 2 peptides linked by disulfied bonds in vessel with C-peptide in a 1:1 ration.
Why can C-peptide be used as an insulin creation measurement?
C-peptide is created in a 1:1 ratio with insulin.
What neural input stimulates insulin release?
Vagal stimulation via acetylcholine acting on M3 receptors bound to Gq activating PLC to increase intracellular calcium.
What hormonal input stimulates insulin release?
Glucagon-like peptide (GLP1) stimulates insulin secretion !
Catecholamines also act to stimulate insulin release via epinephrine surges.
How does epinephrine relate to isnulin?
Epinephrine binds Beta adernergic receptors leading to an increase in insulin surge.
How does Glucose stimulate insulin release?
Glucose in the most potent stimulator of release within the pancreatic Beta cells and does so by increasing intracellular ATP and depolarizing the membrane through the potassium channel and calcium influx.
How is insulin release inhibited?
Norepinephrine via sympathetic response binds alpha adernergic receptors leading to inhibition of insulin release.
Somatostatin released with insulin also causes inhibition of its release.
How does Glucose act on B- islet pancreatic cells
Increases ATP and inhibits potassium channels leading to a membrane depolarization effecting the calcium channels and allowing insulin release.
How do parasympathetics effect insulin release?
Parasympathetic activation of M3 receptors leads to insulin release.
What effect does insulin have on the liver?
promotes anabolism i.e. glycogen synthesis and storage Inhibits glycogen breakdown Increases protein synthesis Increases triglyceride synthesis.
Inhibits Catabolism i.e.
inhibits glycogenolyisis
Inhibits ketogenesis
Inhibits gluconeogenesis
What effect does insulin have on muscle?
Promotes protein synthesis (AA uptake)
Increases glycogen synthesis with GLUT4 glucose utake.
How does insulin act on Fat cells?
Increases triglyceride storage through
promoting free fatty acid uptake
Promoting esterification of free fatty acids
Inhibiting lipolysis
How does somatostatin effect insulin and glucagon?
Somatostatin inhibits both insulin and glucagon release
What two metabolic processes does glucagon mainly promote?
Glycogenolysis Ketogenesis (epinephrine and cortisol do this as well)
What two processes does insulin mainly promote?
Gluconeogenesis
Glycogenesis
Glycolysis.
What does IAPP do and where is it produced?
Produced by the beta cells with insuin and is a negative regulator of glucagon and inhibits GI motility also upregulating appetite.
What does pancreatic polypeptide do and where is it produced?
Secreted by F cells or PP cells and regulated by the vagus nerve.
This provides exocrine effects of the pancrease, gallbladder contraction, gastric acid secretion and GI motitilty.
Think rest and digest!
What does Somatostatin do and where is it released?
Released from Delta cells regulating insulin release.
Regulates through activation os SSTR-5 somatostatin receptor inhibiting insulin release in a paracrine fashion.
What does Ghrelin do and where is it made?
Composed in the Epsilon cells promoting gastric emptying and stimulating apetite.
