Endo 8 Flashcards
The pancreas
Exocrine pancreas - digestive enzymes
Endocrine- alpha cells (10%), beta cells (70-80%), delta cells (3-5%)
Alpha cells
secrete glucagon
secreted when glucose levels fall
stimulates glycogenesis by activating enzyme cascade (each step more potent)
stimulates gluconeogenesis in liver (activate enzymes)
also stimulated after meal high in protein AND during exhaustive exercise
Beta cells
insulin
only hormone that effectively lowers blood glucose
delta cells
somatostatin
depresses secretion of insulin and glucagon
stimulated release by increased blood glucose, amino acids, fatty acids, GI hormones
acts locally to depress secretion of glucagon and insulin
Insulin promotes utilization of _____ for energy and depresses utilization of _______
carbs
fats
Other pancreatic hormones
somatostatin-14 Islet amyloid polypeptide -co-secreted with insulin -cause amyloid deposits in pancreas Pancreatic polypeptide -inhibits bicarb and enzyme secretion by exocrine pancreas
Hypoglycemias effect on insulin and glucagon
inhibits insulin secretion while stimulating glucagon
Hyperglycemia, leucine, arginine and vagal stimulations effect on insulin and glucagon
increase insulin secretion while inhibiting glucagon secretion
Incretins include
gastric inhibitory peptide
glicentin, oxyntomodulin,GLP-1&2
Control of insulin secretion
- regulated by blood glucose levels AND blood AA, GI hormones, glucagon, GH, cortisol and progesterone/estrogen
- blood glucose provides rapid feedback to pancreas for regulating insulin release
- Rise in blood AA must be accompanied by rise in blood glucose for it be a potent stimulator
- GI hormones released before the meal actually absorbed
Factors that can impinge on secretion
vagus stimulation
diet
exercise
Glucose transporters
- insulin exerts part of its actions by affecting membrane glucose transporters GLUT in target cells
- insulin stimulates GLUT 1, 3 and 4 recruitment in the membrane of insulin-responsive cells
- enhances removal of glucose from plasma
Diabetes mellitus
- failure to remove glucose from blood plasma
- two main tpyes, insulin dependent (type I) and non-insulin dependent (type II)
- type I diabetes mainly results from an autoimmune disorder which destroys pancreatic beta
- symptoms appear when 90% or more of beta cells are destroyed
Type II diabestes
more common and associated with obesity
-insulin resistance rather than the lack of insulin appears to be the cause
Hyperglycermia of severe injuries
- non-diabetic individuals who sustain extreme injuries such as massive burns
- stress of injury increases epinephrine and norepinephrine release
- catecholamines inhibit insulin secretion and increase glucagon secretion