29.8: Pancreas produces two hormones that play a large role in managing
the body’s energy supplies.
Clusters of islets are scattered throughout the pancreas, each has a
population of beta cells which produce the hormone insulin and a population
of alpha cells which produce another hormone glucagon. They are
antagonistic hormones that regulate the concentration of glucose in the
blood. They counter each other in a feedback circuit that precisely manages
the amount of circulating glucose available to use as cellular fuel versus the
amount of glucose stored as the polymer glycogen in body cells.
When you eat a carbohydrate rich meal: the rising blood glucose level stimulates the beta cells in the pancreas
to secrete more insulin into the blood. The insulin stimulates nearly all body cells to take up glucose from the
blood, which decreases the blood glucose level. Liver wells take up much of the glucose and use it to form
glycogen which they store. Insulin also stimulates cells to metabolize the glucose for immediate energy use for
the storage of energy in fats, or for the synthesis of proteins. When the blood glucose level falls to the set point
the beta cells lose their stimulus to secret insulin. The blood glucose level starts to di below the set point as it
may between meals or during strenuous exercise, the pancreatic alpha cells respond by secreting glucagon.
Glucagon is a fuel mobilize signaling live cells to break glycogen down into glucose, covert amino acids and fat
derived glycerol to glucose, and release the glucose into the blood, then when the blood glucose level returns to
the set point the alpha cells slow their secretion of glucagon.
29.9: Diabetes mellitus is a serious hor