Met 1: Hormonal Regulation Flashcards
What three cell types are in the endocrine pancreas?
What does each cell type produce?
- beta cells make insulin
- alpha cells make glucagon
- delta cells make somatostatin
Describe the structure of insulin hormone
- Insulin is secreted as a pro-hormone
- C-peptide must be cleaved off to create active hormone
- Active insulin is made up of two chains bound by disulfide bonds
How does glucose stimulate release of insulin from beta cells?
- Glucose enters beta cell via GLUT2 transporter
- Glucokinase phosphorylates glucose
- G6P proceeds through glycolysis
- Increased ATP levels cause K channel to close
- Beta cell depolarizes
- Voltage sensitive calcium channels open
- calcium allows vesicles filled with insulin to exocytose
There are three phases of insulin release.
True or false?
False.
Insulin release is biphasic
Describe the signaling pathway triggered by insulin at its receptor
(5 steps)
- Insulin binds to alpha portion of receptor
- Beta portion of receptor phosphorylates itself
- IRS binds to receptor
- IRS becomes phosphorylated
- PI3 Kinase (METABOLIC pathway) and MAP kinase (GROWTH pathway)
What is the effect of PI3 Kinase activity?
PI3 kinase causes the METABOLIC effects of insulin
- GLUT4 translocation to cell membrane
- Nitric oxide production
What is the effect of MAP Kinase activity?
MAP Kinase activity is insulin’s growth pathway
In insulin resistance, are both the PI3 Kinase and MAP kinase pathways broken?
NO! Only the metabolic pathway (PI3 kinase) is broken
What is the effect of insulin on
- Glycogenolysis in liver
- Gluconeogenesis in liver
- Glucose uptake by muscle/fat
- Glycogen synthesis
- Fat uptake
Insulin causes
- DECREASED Glycogenolysis in liver
- DECREASED Gluconeogenesis in liver
- INCREASED Glucose uptake by muscle/fat
- INCREASED Glycogen synthesis
- INCREASED Fat uptake
INSULIN OVERALL = NUTRIENT STORAGE
T2D causes
- _____ Liver glucose production
- ______ Uptake of glucose
- ______ Fat release from adipose
- _______ Glucagon release
- ______ GLP-1
T2D causes
- Increased Liver glucose production
- Decreased Uptake of glucose
- Increased Fat release from adipose
- Increased glucagon release
- Decreased GLP-1
When is glucagon secreted?
When blood glucose falls.
aka opposite of insulin secretion
What is the incretin effect?
More insulin is released when glucose is given orally compared with IV administration (more insulin for same increase in plasma glucose)
Due to GLP-1
GLP-1 is released in response to ________.
It causes _________.
It inhibits __________.
GLP-1 is released in response to meals.
It causes more insulin to be released for the same amount of glucose (potentiates insulin release).
It inhibits glucagon release.
GLP-1 is made in ______ and gets degraded by __________.
GLP-1 is made in intestinal L cells and gets degraded by DPP4.
What effect do catecholamines have on blood sugar?
Catecholamines raise blood glucose
