[FMS] NAM - integration of metabolism 1 Flashcards
(30 cards)
what are the prime regulators of metabolism?
insulin and glucagon
what are 3 insulin counter-regulatory hormones
adrenaline (adrenal medulla)
cortisol (adrenal cortex)
growth hormone (anterior pituitary)
insulin secretion is stimulated by
increase blood glucose
increase amino acid conc
gut hormones (secretin and GI hormones)
Glucagon
what is insulin secretion inhibited by
adrenaline
secretion of glucagon is stimulated by
low blood gluc
high conc of amino acids
adrenaline
insulin receptor structure
-4 polypeptide chains
-alpha subunit-extracellular
-beta subunit-intracellular
-3 sites of phosphorylation
-insulin receptor has enzyme activity-it is enzyme itself
-tyrosine kinase-involved in growth and differentiation
out of insulin and glucagon, which is hypoglycaemic and which is hyperglycaemic
- Insulin is the only hypoglycaemic hormone.
- Glucagon is a hyperglycaemic hormone
How is insulin formed?
- Insulin is coded for by its one polypeptide chain which is pro-insulin.
- When pro-insulin is secreted in the vesicles we get proteolysis.
- This forms two polypeptide chains and whats left is C-peptide in the circulation.
- Now that C-peptide is removed it can act.
which one is hyperglycaemic/ hypoglycaemic out of glucagon and insulin
- Insulin is the only hypoglycaemic hormone.
- Glucagon is a hyperglycaemic hormone
Describe the composition of the islets of Langerhans.
β cells (60-70%) secrete insulin
α cells (30-40%) secrete glucagon
δ cells secrete somatostatin
How is insulin formed?
- Insulin is coded for by its one polypeptide chain which is pro-insulin.
- When pro-insulin is secreted in the vesicles we get proteolysis.
- This forms two polypeptide chains and whats left is C-peptide in the circulation.
- Now that C-peptide is removed it can act.
when insulin binds to its receptor, how many places does it phosphorylate, and what happens in these places?
When insulin binds to the receptor, the receptor acts as a tyrosine kinase and phosphorylates itself.
So it auto phopshorylates and it phosphorylates at 3 places.
- The first is a docking site for the insulin receptor substrate - this is involved in metabolic effects.
- The second is involved in activating other kinases.
- The third is involved in the longer term effects of insulin, which are to do with growth.
what happens when insulin binds to an insulin receptor?
what happens after AKT/PKB if formed?
whats another name for AKT
Protein Kinase B (PKB)
what happens to AKT and GSK when insulin is high
what happens to AKT and GSK when insulin is low
Outline the inhibition of lipolysis in adipocytes by insulin.
what does insulin inhibit in fatty acid synthesis?
inhibits hormone sensitive lipase
What is the effect of insulin on gene expression through Ras and MAPK?
- This process concerns the bottom part of the phosphorylated receptor.
- There is the docking protein, SHC, and also Ras present.
- Ras uses GTP.
- There is a cascade which involves Raf, which phosphorylates and activates MEK kinase, which then phosphorylates and activates MAPK (mitogen-activated protein kinase).
- MAPK acts on transcription factors and it either increases or decreases the synthesis of some proteins.
- This is the long term effect as it is an effect on gene expression rather than activation/inactivation of enzymes.
what does glucagon activate?
activates glycogenolysis (liver)
activates **gluconeogenesis (liver) **
activates uptake of amino acids by the liver for gluconeogenesis
activates FA release from adipose tissue
activates FA oxidation and ketone body formation in the liver
what does adrenaline stimulate?
stimulates glycogenolysis (muscle and liver)
stimulates fatty acid release from adipose tissue
what does cortisol stimulate?
stimulates aa mobilisation from muscle
stimulates gluconeogenesis
stimulates FA release from adipose tissue
whats the function of glucagon
mobilises fuel
maintains blood glucose during fasting
