based on pp and easygen
What cells of the pancreas secrete insulin?
b-cells
What cells of the pancreas secrete glucagon?
a-cells
What cells of the pancreas secrete somatostatin?
d-cells
Blood flow in the cells of the pancreas flow from…
the center to the periphery
Insulin is what kind of hormone?
a. steroid
b. peptide
c. fatty acid
d. thyroid
b
Does insulin have a short or long half-life?
short
Measuring C-peptide tells us what?
how much insulin was made in the pancreas
What is the major stimulus for insulin release?
glucose
Besides glucose, what are some other stimuli that can cause the release of insulin from beta cells?
parasympathetic stimulation
Ach (Acetyl Choline)
Incretins
What GLUT transporter is located on b-cells of the pancreas?
a. GLUT1
b. GLUT2
c. GLUT3
d. GLUT4
b
The first step of insulin release is that glucose flows down the concentration gradient through __________ transporters in the beta cell.
GLUT2
The second step of insulin release is that glucose undergoes what?
metabolism
When glucose is metabolized it produces what? (step 3)
ATP
The fourth step of insulin release is that an increase of ATP causes what channel to close?
K+ channels
After closing K+ channels, the cell depolarizes and that allows what type of channels to open up?
V-gated Ca++ channels
When the Ca++ levels of the cell start to rise, that causes vesicles full of insulin to undergo __________.
exocytosis
Summary of the steps for insulin release:
glucose flows down the concentration gradient through GLUT2 transporter into b-cell
glucose undergoes metabolism
ATP is produced
Increase of ATP causes K+ channels to close (causes b-cell to depolarize)
Depolarization allows V-gated Ca++ channels to open
rise in intracellular Ca++
Increase in Ca++ causes vesicles full of insulin to exocytose
Insulin is released into the bloodstream
Sulfonylurea drugs target what step of insulin release? What do these drugs do?
They target the K+ channels. They act like ATP and CLOSE K+ channels.
The insulin receptor is what kind of kinase?
tyrosine
Do tyrosine kinase receptors dimerize?
yes
What are the main physiological actions of insulin? (actions on blood glucose, fatty acids, ketoacids, amino acids, K+ uptake, etc.)
decrease blood glucose
decrease fatty acid and ketoacids in the blood
decrease blood amino acid conc.
others:
increase K+ uptake
potentiate the effects of growth hormone
How does insulin decrease blood glucose?
increase glucose transport into muscle/fat
increase glucokinase activity (in liver)
promotes formation of glycogen
inhibit gluconeogenesis
Upregulating glucose transporters in tissues increases/decreases blood glucose.
decreases
What GLUT transporters are insulin sensitive?
GLUT4
Glucagon is secreted when blood glucose concentration _______.
a. rises
b. falls
b
Like insulin, glucagon is a __________ hormone.
peptide
Besides low blood glucose/ hypoglycemia what are some other things that stimulate the release of glucagon?
increase AA concentration
b-adrenergic agonists
Ach
exercise
cortisol
What are some things that inhibit the release of glucagon?
insulin
hyperglycemia
secretin
somatostatin
free fatty acids
Glucagon mainly affects which of the following?
a. pancreas
b. muscle
c. adipose tissue
d. liver
d
What are the main actions of glucagon?
INCREASE GLUCOSE
stimulate glycogenolysis (liver)
stimulate gluconeogenesis
stimulate lipolysis
What type of diabetes is insulin-dependent and is where there is decreased insulin secretion?
type 1 diabetes
What are the causes of type 1 diabetes?
destruction of b-cells: autoimmune, viral
inherited diseases
What are the symptoms of type 1 diabetes?
hyperglycemia (elevated plasma glucose and glucose production)
glucose in the urine
dehydration
vascular changes
ketoacidosis (bc too much fat—> energy)
Is type 2 diabetes insulin dependent?
no
Type 2 diabetes results from decreases sensitivity of ____________________ to insulin
target tissues
Symptoms of type 2 diabetes:
elevated insulin levels
metabolic syndrome: obesity, insulin resistance, hyperglycemia, HTN, atherosclerosis
What is the tx for type 1 diabetes?
insulin injections
What is the treatment for type 2 diabetes?
diet changes, exercise, weight loss
insulin injections
sulfonylurea drugs
others