Describe and explain the process of insulin secretion
Beta cells store insulin in vesiclesAt normal blood glucose concentration (BGC), K+ channels are open, so K+ can diffuse out of the cell to maintain the potential difference (PD) at -70mVWhen the BGC rises, glucose enters the cells by facilitated diffusion via transporter proteinsThis glucose is phosphorylated in the cell by glucokinase and is used in metabolism to produce ATPK+ channels are ATP sensitive so they close, meaning the PD reduces to -30mV as K+ can no longer diffuse out (more positive ions in the cell)This depolarisation causes voltage-gated Ca2+ channels to openCa2+ diffuses into the cell, triggering the fusion of the vesicles with the cell membraneThe insulin is then secreted out of the cell via exocytosis
SH
Related Biology A Level answers
All answers ▸Mitosis is the process of cell division, it occurs in humans and in plants. Compare and contrast the process of mitosis in human cells and in plant cells (5 marks)
What are enzyme inhibitors?
How does muscle contraction work?
Describe the involuntary Relay Arc pathway of a nervous impulse, from the stimulus to the reaction