**Question:** Glucagon acts via

A. α-receptors
B. β-receptors
C. Insulin receptors
D. Glucose transporters

**Core Concept:** Glucagon is a peptide hormone secreted by the α-cells of the pancreas in response to low blood glucose levels. Its primary function is to increase blood glucose levels by promoting glycogenolysis and gluconeogenesis in the liver.

**Why the Correct Answer is Right:** Glucagon acts via α-receptors, specifically on the α-cells of the pancreas and hepatocytes. When glucagon binds to these α-receptors, it stimulates glycogenolysis and gluconeogenesis, ultimately increasing blood glucose levels.

**Why Each Wrong Option is Incorrect:**

A. Glucagon does not act on α-receptors, contradicting the correct answer.
B. Glucagon does not act on β-receptors, as its primary action is on α-cells and hepatocytes.
C. Glucagon does not act on insulin receptors, as insulin and glucagon exert opposing effects on glucose homeostasis.
D. Glucagon does not act directly on glucose transporters, as its primary action is to stimulate glycogenolysis and gluconeogenesis, which increases glucose release from liver cells.

**Clinical Pearl:** Understanding the correct mode of action of glucagon is crucial for managing hypoglycemia, a condition characterized by low blood glucose levels. In cases of severe hypoglycemia, glucagon can be administered intravenously as an emergency treatment.

**Correct Answer:** A. α-receptors

**Explanation:** Glucagon acts on α-receptors to stimulate glycogenolysis and gluconeogenesis, ultimately raising blood glucose levels in response to low blood glucose conditions.