hormonal communication

Question 1

how is insulin released

Answer 1

glucose diffuses into cells and is respired into ATP.
ATP blocks the k+ ion channel preventing k+ from leaving so k+ accumulates in the cell causing cell membrane to become depolarised
ca2+ ion channels open and calcium ions diffuse
this results in the movement of vesicles containing insulin to move towards the plasma membrane and is released via exocytosis

Question 2

how is glucagon involved in regulation of blood glucose levels

Answer 2

glucagon is released by alpha cells in the pancreas.
it causes the conversion of glycogen into glucose by glycogenolysis. Gluconeogenesis also occurs when noncarbohydrate molecules are converted into glucose.
negative feedback reduces the secretion of glucagon

Question 3

what occurs when adrenaline reaches cell surface membrane

Answer 3

adrenaline binds to a receptor which is complementary to it
adenylyl cyclase is activated
ATP converted to camp
camp activates other enzymes