islets of langerhans
What makes up the endocrine pancreas?
hyperglycemic factor that mobilizes glycogens stores
islet polypetide that modulates appetite and gastric emptying and glucagon and insulin secretion
inhibits secretion of insulin, glucagon, and pancreatic polypeptide
stimulates gastric acid secretion
small protein that facilitates digestion
inhibits the secretion of glucagon only
stimulates the secretion of insulin and somatostatin
cell that releases glucagon and proglucagon
cell that releases insulin, c-peptide, proinsulin, amylin
cell that releases somatostatin
cell that releases pancreatic polypeptide
insulin forms complexes with this in the B cells
insulin and glucagon
These are secreted by exocytosis and cross the basal lamina of the cell and the basal lamina of the capillary before entering the lumen of the capillary
promotes synthesis and storage of glycogen, triglycerides, and protein in its major target tissues
increased blood glucose, incretins, vagal nerve stimulation, others
What stimulates the release of insulin?
promotes storage of fat and glucose, influences cell growth, promotes protein formation and prevents degradation of proteins
What are various roles of insulin?
increase transport of glucose, A.A., and K+ into cells
What are the rapid effects of insulin?
increase in mRNA for lipogenic and other enzymes
What is the delayed effect of insulin?
Adipose tissue, muscle, liver, general increase in cell growth
What are the effects of insulin on various tissues?
glucose, mannose, A.A., glucagon, etc
What are some stimulators of insulin secretion?
somatostatin, thiazide diuretics, K depletion, phenytoin, etc
What are some inhibitors of insulin secretion?
2 alpha and 2 beta glycoprotein subunits
What makes up the tetramer of an insulin receptor?
Which subunits of the insulin receptor bind insulin?
tyrosine kinase activity
This activity is found on the intracellular portions of the insulin receptor
autophosphorylation of the subunits on tyrosine residues
What does binding of insulin to insulin receptors produce on tyrosine residues?
phosphatidylinositol 3-kinase (PI3K)
What mediates the growth-promoting protein anabolic effects of insulin?
insulin receptor substrate - 1
Mediates the effects of glucose, fat, and protein metabolism
tyrosine kinase receptors, serine threonine receptors, cytokine receptors, G-protein coupled receptor
What are some cardioprotective receptors?
Insulin growth factor - 1
Plays an important role in childhood growth and continues to have anabolic effects in adults
Insulin growth factor - 2
growth promoting hormone during gestation
long single-chain protein molecule that is processed within the Golgi of Beta cells and packaged into granules
How is insulin stored in the body?
facilitated diffusion or secondary active transport (in intestine and kidneys)
How does glucose enter cells?
sodium-dependent glucose transporters
Which transporters are responsible for the secondary active transport of glucose in the intestine and renal tubes?
glucose transporter on Beta cells of islets, liver, epithelial cells of small intestine, and kidneys
Glucose transporter on skeletal and cardiac muscle, adipose tissue, and other tissues
phosphatidylinositol 3 kinase (PI3K)
What speeds translocation of the GLUT-4 containing endosomes into the cell membrane?
Stimulates the release of insulin by exocytosis
ATP from glucose metabolism inhibits K channels which depolarizes the Beta cell
What causes calcium influx of a Beta cell?
decreased glucose uptake, increased protein catabolism, increased lipolysis
What is the result of insulin deficiency (and glucagon excess)?
cessation of secretion of endogenous insulin
What is done by the body to compensate for hypoglycemia?
What is processed in A and L cells and raises blood glucose levels?
What is preproglucagon processed into in L cells?
What is preproglucagon processed into in A cells?
A cells of pancreatic islets and the GI tract
Where is glucagon produced?
Glucagon-like polypeptide 1
What is a potent stimulator of insulin secretion that also increases glucose utilization?
What is formed in L cells that inhibits gastric acid secretion?
What does glucagon cause in the liver?
decreases the motility of the stomach, duodenum, and gallbladder
decreases both secretion and absorption in the GI tract