26: Glucose metabolism, energy balance and obesity Flashcards
What occurs during hypoglycemia? (low levels of glucose)
Decreased CNS function, coma, death
What occurs during hyperglycemia? (high levels of glucose)
Osmotic diuresis, dehydration, vascular collapse, death
What is the hormone of the absorptive state?
Anabolic: high insulin
What is the hormone of the post absorptive state?
Catabolic: high glucagon
What do beta cells secrete?
Insulin
What do alpha cells secrete?
Glucagon
What do delta cells secrete?
Somatostatin
Describe the control of insulin secretion
slides Increase in plasma glucose –> Increase in insulin secretion in pancreatic islet beta cells –> plasma insulin —> Adipocytes and muscle (increase glucose uptake). Cessation of glucose output; net glucose uptake in the liver –> Restoration of plasma glucose to normal
What are the three main types of tissues that insulin acts on
-Muscle -Liver -Adipose
Describe the insulin receptor
Insulin receptor is a tyrosine kinase; autophosphorylates tyrosine and phosphorylates tyrosine of substrate proteins
What is the role of glucagon
If blood glucose levels drop too low, glucagon increases glucose release from cellular stores Glucagon is a peptide hormone produced by alpha cells in the Islets of Langerhans that opposes insulin actions in order to: -Increase glycogenolysis (liberating glucose) -Increase gluconeogenesis (synthesising glucose) -Increase ketone synthesis
How are glucagon actions mediated?
Via a G-protein coupled receptor to activate adenylate cyclase and PKA
Describe the control of glucagon secretion
slides
What occurs during type 1 diabetes
A loss of beta cells in the pancreas leads to a deficiency in insulin
What occurs during type 2 diabetes?
Due to insulin resistance or reduced insulin sensitivity
