Which of the hormones is secreted by alpha-cells in the pancreas in response to low blood glucose levels?
**Core Concept:** Alpha cells are a type of pancreatic endocrine cell that produce and secrete glucagon, a hormone responsible for raising blood glucose levels when they drop too low (hypoglycemia).
**Why the Correct Answer is Right:** Glucagon is a hormone secreted by alpha cells in response to low blood glucose levels. When blood glucose levels drop below a certain threshold, the alpha cells in the pancreas become activated, which leads to glucagon release into the bloodstream. Glucagon acts on liver cells (hepatocytes) to increase glucose production by initiating glycogenolysis and gluconeogenesis, thereby raising blood glucose levels back to a safe range.
**Why Each Wrong Option is Incorrect:**
A. Insulin (Option A) is responsible for lowering blood glucose levels by promoting glucose uptake by cells and reducing hepatic glucose production. It is produced by beta cells in response to high blood glucose levels.
B. Glucagon (Option B) is the correct hormone released by alpha cells during hypoglycemia, not glucagon.
C. Somatostatin (Option C) is a hormone secreted by delta cells in the pancreas. It has an inhibitory effect on the secretion of other pancreatic hormones like insulin and glucagon. In this context, it is incorrect because it opposes the action of glucagon.
D. Gastrin (Option D) is a hormone produced by G cells in the stomach, not alpha cells in the pancreas. It is involved in regulating gastric acid secretion and does not play a role in blood glucose regulation.
**Clinical Pearl:** Hypoglycemia can be a symptom of various underlying conditions like diabetes, liver disorders, or medications. It is crucial for healthcare professionals to promptly recognize and manage hypoglycemia to prevent severe complications.