Unit 2 - Endocrine Pancreas Flashcards
What specifically secretes insulin and glucagon?
islets of Langerhans
What is the chemical nature of insulin and glucagon?
they are peptides
What is the general function of insulin and glucagon?
rapid and powerful regulators of metabolism
Which tissues does insulin act on?
the liver, adipose tissue, and muscle
Which tissues does glucagon act on?
the liver alone
How do insulin and glucagon regulate metabolism (generally)?
they coordinate the disposition of nutrient inputs from meals and control the flow of endogenous substrates during fasting
What hormones oppose the anabolic function of insulin?
glucagon, cortisol, epinephrine, and growth hormone
Which anatomical arrangement predisposes the liver to be the primary target of insulin and glucagon action?
the portal venous system; the pancreatic and mesenteric veins empty directly into the portal vein which goes into the liver
What are the effects of insulin on fuel storage and breakdown in the insulin sensitive tissues?
Insulin increases fuel storage and decreases the amount of fuel breakdown in the liver, muscles, and adipose
How does insulin facilitate glucose uptake in muscle and adipose tissue?
GLUT 4, which is regulated by insulin, facilitates glucose diffusion into cells of adipose tissue and muscle
How does insulin facilitate glucose uptake in the liver?
insulin stimulates phosphorylation of intracellular glucose and maintains the high concentration gradient in hepatocytes
What glucose transporters are insulin independent?
GLUT 2 and GLUT 3
Which stimuli are the main triggers of glucagon secretion?
low blood glucose and high amino acids
What are the main effects that glucaon has on flow of fuels?
it increases fuel breakdown and decreases fuel storage in the liver; no effect in muscle and adipose
What is glucagon known as?
an insulin antagonist
