Vitamins, Harmones and Hemoglobin
Which one of the following statements about glucagon is correct?
|A||High levels of blood glucose increase the release of glucagon from the a cells of the pancreas.|
|B||Glucagon levels decrease following ingestion of a protein-rich meal.|
|C||Glucagon increases the intracellular levels of cAMP in liver cells, causing an increase in glycogen breakdown.|
|D||Glucagon is the only hormone important in combating hypoglycemia.|
a. The cAMP cascade initiated by glucagon causes the liver to degrade glycogen, releasing glucose to the blood. High levels of blood glucose decrease the release of glucagon from the α cells of the pancreas.
b. Glucagon levels increase following ingestion of a protein-rich meal. In addition to glucagon, epinephrine and cortisol are also important in increasing glucose production in hypoglycemia. Glucagon increases the formation of ketone bodies by the liver.