Pancreatic Hormones HW Questions Flashcards
What islet cell produces insulin?
beta
What islet cell produces glucagon?
alpha
What islet cell produces somatostatin?
delta
insulin inhibits
glucagon
amylin inhibits
insulin
somatostatin inhibits
insulin and glucagon
What is the correct order of insulin synthesis?
1) ribosomes produce preproinsulin
2) ER produces proinsulin
3) golgi apparatus packages insulin and C peptide
Beta cells monitor blood glucose levels by _________ of glucose above physiological range into _______________ through glut2 receptors
uptake, beta cells
What happens when ATP formed from glucose breakdown closes potassium channels in the beta cells membrane?
cell depolarizes
What event opens voltage gated calcium channels in beta cell membranes?
depolarization of membrane
What role does calcium play in the release of insulin?
stimulates release
How are multiple beta cells able to release insulin simultaneously?
they have gap junctions
What other products are released with insulin from beta cells?
proinsulin and C peptide
What plasma product is tested in blood to determine if type 1 and/or type 2 diabetics are producing some insulin?
C peptide
What system/mechanism regulates insulin secretion?
negative feedback
What stage of insulin secretion releases a large quantity of stored insulin into the blood?
acute stage one
When does the delayed/sustained stage of insulin secretion begin after the acute stage?
about 15 min later
What effect do certain amino acids combined with glucose have on insulin secretion?
doubles secretion
What effect does insulin have on amino acids?
promotes transport into cells and protein synthesis
What allows skeletal muscles to uptake glucose without insulin?
moderate to heavy exercise
What is the primary most important effect of insulin?
causes the liver to uptake most of the excess glucose and store it as glycogen
What secondary effect does insulin have on the liver?
inhibit glucose synthesis
How does insulin effect fat metabolism?
promotes synthesis and storage
Why is insulin considered a fat sparer?
it inhibits lipase
How does insulin effect protein metabolism?
promotes synthesis and storage
How does insulin effect ribosomes during protein synthesis?
turns them on
What functions does insulin share with growth hormone?
facilitate cellular uptake of AAs and inhibit protein catabolism
Why can long term insulin def or insensitivity cause atherosclerosis?
increased FAs causes the liver to increase cholesterol production
Why does insulin def or insensitivity increases the risk of ketoacidosis?
increases use of FAs for energy production
How does long term insulin def or insensitivity effect protein metabolism?
inhibits synthesis and increases catabolism
How does long term insulin def or insensitivity effect liver gluconeogenesis?
no longer needed
Over secretion of which hormone can cause insulin insensitivity?
cortisol and growth hormone
Why does insulin insensitivity cause hyperinsulinemia?
high blood glucose causes negative feedback of insulin secretion
Why is hyperinsulinemia associated with PCOS?
excessive levels of insulin will stimulate ovaries to over produce androgens
What activity stimulates the release of somatostatin?
ingesting food
What is the primary goal of somatostatin?
slow down digestion
Which cells are directly affected by somatostatin?
alpha and beta islet cells
Which hormone does somatostatin inhibit?
insulin and glucagon
What other hormone has the same chemical make up as somatostatin?
growth hormone inhibitory hormone (GHIH)
What conditions stimulate secretion of glucagon?
low blood glucose
What is the primary function of glucagon?
increase blood glucose
How does glucagon achieve its primary function?
stimulate liver gluconeogenesis and glycogenolysis
What effect does glucagon have on fats?
activate lipase
What effect does NE have on glycogen?
stimulate skeletal muscle to breakdown of stored glycogen
How does the body regulate plasma calcium levels?
negative feedback
Where is calcitonin produced?
parafollicular cells
How does calcitonin promote building or strength of bone?
decreases activity of osteoclast and increases activity of osteoblast
What stage of life does calcitonin have the strongest effect?
childhood
When does the body release calcitonin?
when serum calcium levels are high
Where is parathyroid hormone produced?
parathyroid glands
Where are the glands located that produce PTH?
posterior aspect of the thyroid gland
How does PTH cause resorption of bone?
increase osteoclast activity
When is PTH released?
when plasma calcium levels are low
How does PTH effect the kidneys?
stimulates the kidneys to activate vit D and reabsorb calcium from the filtrate
How does PTH effect the intestines?
increases calcium absorption
What role does vit D play in effecting calcium levels in blood?
aids in absorbing calcium from the intestinal tract
What is the precursor for vit D synthesis?
cholesterol
What is vit D’s role in formation of calbindin?
stimulate synthesis
How does calbindin effect calcium absorption from intestines?
increases absorption several weeks
