Stimulates hepatic glucose production
Stimulates lipolysis
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What is the major effect of growth hormone?
Stimulates hepatic glucose production, lipolysis
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What is the major effect of cortisol?
Stimulates hepatic glucose production
Stimulates proteolysis
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What is Beta-oxidation?
Fatty acids converted into Acetyl-CoA
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What is ketogenesis?
Production of ketone bodies from Acetyl CoA
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What is the metabolic response to hypoglycaemia?
The immediate response is glucagon release from alpha cells in the pancreas.
Hepatic glucose output is also stimulated.
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What are the defences against hypoglycaemia?
Short term:
- Glucagon
- Epinephrine
- Sympathetic NS
Medium term:
- Ketogenesis - Fat reserves are a partial substitute for glucose
Long term:
- Cortisol stimulates proteolysis to supply amino acid substrates for gluconeogenesis
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What is the normal, healthy plasma glucose concentration?
5mmol/l
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What is the islets of Langerhans?
Clusteres of endocrine cells surrounded by exocrine pancreas
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Where is the venous drainage of the pancreas into?
The hepatic portal vein - half of the secreted insulin is metabolised by the liver in its first pass.
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What is a good index of insulin?
C-peptide as one mole of C-peptide is secreted for each mole of insulin
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How do B cells sense a rise in glucose?
Glycolysis forms ATP
This closes ATP gated K channels causing membrane depolarisation. This then leads to increased Ca entry triggering insulin exocytosis.
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How does glucose get into cells?
Sodium glucose transporters (SGLTs)
SGLT1: glucose absorption from gut
SGLT1, SGLT2: glucose reabsorption from kidney (PCT)
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What are the different glucose transporters?
GLUT1: brain and erythrocytes - high affinity for glucose
GLUT2: liver, kidney, pancreas, gut - low affinity for glucose
GLUT3: brain - high affinity
GLUT4: muscle and adipose tissue - medium affinity
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