Control of insulin secretion

Question 1

Outline the control of insulin secretion

7 stages

Answer 1

1) At normal blood glucose concentration levels, potassium channels in the plasma membrane of beta cells are open and potassium ions diffuse out of the cell
- The inside of the cell is at a cell potential of -70mV

2) When glucose concentration rises, glucose enters the cell by a glucose transporter
3) Glucose is metabolised inside the mitochondria, resulting in the production of ATP

4) ATP binds to potassium channels and causes them to close
- ATP-sensitive potassium channels

5) Potassium ions can no longer diffuse out of the cell, the potential difference reduces to around -30mV and depolarisation occurs.
6) Depolarisation causes the voltage-gated calcium channels to open
7) Calcium ions enter the cell and cause secretory vesicles to release the insulin they contain by exocytosis