Glucagon secretion from pancreatic alpha cells is stimulated by which of the following?
- A Hypoglycemia, decreased insulin, arginine infusion, sympathetic stimulation (beta-2 receptors), and exercise ✓
- B Hyperglycemia, increased insulin, arginine infusion, and somatostatin
- C Fatty acid infusion, ketone bodies, and high glucose — all stimulate glucagon
- D GLP-1, GIP, and CCK are the primary stimulants of glucagon independent of glucose levels
Explanation
Glucagon is a counterregulatory hormone secreted when blood glucose falls. Stimulants include: hypoglycemia (primary trigger), amino acids (especially arginine and alanine — explaining why protein meals raise glucagon), decreased insulin (paracrine effect within islet), sympathetic stimulation (beta-2 adrenoceptors on alpha cells — important in hypoglycemia stress response), and exercise. Inhibitors of glucagon secretion include hyperglycemia, insulin (paracrine), somatostatin, free fatty acids, and ketone bodies. GLP-1 inhibits glucagon (unlike its stimulatory effect on insulin).
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
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