Question

Insulin enhances the transport of glucose from the blood into most of the body cells, its secretion is controlled by a negative-feedback system between the concentration of glucose in the blood and the insulin-secreting cells, therefore which of the following statements is correct?

Select one:

a. A decrease in blood glucose concentration stimulates insulin secretion, which in turn further lowers the blood glucose concentration

b. An increase in blood glucose concentration stimulates insulin secretion, which further increases the blood glucose concentration

c. A decrease in blood glucose concentration stimulates insulin secretion, which in turn increases the blood glucose concentration

d. An increase in blood glucose concentration stimulates insulin secretion, which in turn lowers the blood glucose concentration

Answer 1

d). An increase in blood glucose concentration stimulates insulin secretion, which in turn lowers the blood glucose concentration.

Insulin is a hormone secreted by beta cells of pancreas, it lowers the blood glucose level by increasing the glucose intake of the cells. Normally the cells need glucose for production of energy . The cells can take glucose in the presence of insulin , and excess glucose is stored as glycogen in liver and muscles and broken down in the time of need . Normally insulin is secreted in our body after any intake , when glucose levels are higher. If insulin is not secreted in required amount then blood glucose levels keeps on increasing leading to a condition called diabetes mellitus . Here blood glucose remains higher and cells cannot take up glucose from blood due to decreased insulin. So the cells starve and as a result develop ketoacidosis due to alternate use of ketones as fuel .

The normal blood glucose level is 80 to 120 mg / dl .

When blood glucose level is decreased below 70 it is sensed by alpha cells of pancreas which secrete glucagon, which inturn functions opposite to that of insulin by increasing blood glucose level ,in response to decreased blood glucose levels.