Which hormone's production is stimulated when glucose levels are low in the body?

• A. Insulin
• B. Glucagon
• C. Prolactin
• D. Thyroid hormone

Answer: (B)

The production of glucagon is stimulated when glucose levels are low in the body because this hormone plays a critical role in glucose homeostasis. Glucagon is secreted by the alpha cells of the pancreas and its primary function is to increase blood glucose levels through glycogenolysis, which is the breakdown of glycogen into glucose stored in the liver, and gluconeogenesis, which is the synthesis of glucose from non-carbohydrate sources. When blood glucose levels fall, glucagon acts to raise them back to normal levels, ensuring that the body's cells receive the necessary glucose for energy.

In contrast, insulin is secreted when glucose levels are high to lower blood sugar rather than when they are low, while prolactin is involved in milk production and has no direct impact on glucose levels. Thyroid hormones, although they play multiple roles in metabolism, do not specifically respond to glucose levels in the same way glucagon does. Thus, when the body senses low levels of glucose, glucagon is the primary hormone that is released to restore balance.