Which hormone is responsible for increasing blood glucose levels when they are low?

• A. Insulin
• B. Glucagon
• C. Cortisol
• D. Adrenaline

Answer: (B)

The hormone responsible for increasing blood glucose levels when they are low is glucagon. This hormone is produced by the alpha cells of the pancreas and has the primary function of signaling the liver to release stored glucose into the bloodstream. When blood glucose levels drop, glucagon acts to stimulate the conversion of glycogen (the stored form of glucose) back into glucose, which is then released into the bloodstream, thereby raising blood glucose levels to a more normal range.

This response is crucial in maintaining homeostasis, especially during periods of fasting or intense physical activity when glucose levels can fall. While other hormones, such as cortisol and adrenaline, can also influence blood sugar levels, they do so in different contexts and primarily have other primary functions. Insulin, on the other hand, works oppositely by lowering blood glucose levels when they are high, making glucagon the key hormone for increasing blood glucose in response to low levels.