Hoeostasis

Question 1

What happens when blood glucose is low

Answer 1

• Pancreases detects fall in glucose levels so α cells produce glucagon
  
  • Attaches to specific receptor proteins on target cells - liver
  • Activate enzymes which convert glycogen into glucose - glycogenolysis
  • When glycogen supply are low glycogen can also convert amino acids and glycerol into glucose (gluconeogenesis)

Question 2

What happens when blood glucose is too high?

Answer 2

• Pancreas detects rise in blood glucose and so β cells secret insulin into the blood stream
  
  • Insulin attaches to specific receptors on target cells - liver, muscle
  • Simulates- the inclusion of more specific glucose channel proteins in the membrane - glucose diffuse in (increases permeability)
  • Activates enzymes that convert glucose int glycogen (glycogenesis) or fat when stores are full

Question 3

Describe the second messenger system

Answer 3

• Glucagon and adrenalin bond to receptors on the outside of cells but don’t enter (first messenger)
  
  • When they bind they activate adenyl cyclase in the membrane which converts ATP - cyclic AMP (second messenger)
  • Cyclic AMP activates protein kinase - stimulates hydrolysis of glycogen to glucose - released into blood