M3 - Endo Pancreas Flashcards
Insulin
- Half life 3-5 minutes (permits rapid changes in circulating levels)
- Cleared by insulinases in liver (50%),
kidney, placenta
C-peptide
- Half life 3-4x insulin (endogenous insulin production and secretion)
- Degraded by kidney
Glucose-stimulated insulin secretion
- Glucose enters via GLUT2
- Metabolized into ATP
- Closes ATP-dep K channel
- Opens Ca channel
- Induces fusion of insulin vesicles to plasma membrane
Insulin secretion is directly affected by plasma ___ levels
glucose
____ is the rate- limiting step in this process
Glucokinase
Closure of ___ channels increases insulin secretion
K-dep ATP
Insulin release requires ___
Calcium
Sulfonylureas and GLP-1 agonists
Block ATP-dependent potassium channels
DPP4 Inhibitors
DPP4 enzyme breaks down GLP-1
Translocation of ___ to the cell
membrane is induced by insulin binding the insulin receptor
GLUT 4
Islets of Langerhans
5-10x exocrine blood flow
Glucagon action
1.Binding of glucagon to GPCR activates adenylyl cyclase
2. Rise in cAMP
3. Activation of cAMP-dependent kinases
4. Activation/inhibition of enzymes involved in carb/lipid metabolism
*Predominantly hepatocytes
GLP-1
Stimulates: BIGS
-Insulin secretion
-Somatostatin secretion
-Beta cell proliferation
-Gastric acid secretion
Inhibits: BAG
-Gastric emptying
-Appetite
-Beta cell death
GLP-1 RA activate ___ receptor to exert effects
Used as medication in ___
-GLP 1
-Type 2 DM
Relative amounts of insulin and glucagon released by the pancreas are regulated so that rate of hepatic glucose production is ____ to use of glucose by peripheral tissues
EQUAL
