Biological Systems MCAT Practice Exam

What hormone is secreted by the pancreas to lower blood glucose levels?

1. Glucagon

2. Cortisol

3. Insulin

4. Epinephrine

The correct answer is: Insulin

The hormone that is secreted by the pancreas to lower blood glucose levels is insulin. Insulin is produced by the beta cells in the islets of Langerhans, which are specialized clusters of cells in the pancreas. When blood sugar levels rise after eating, insulin is released into the bloodstream. Its primary function is to facilitate the uptake of glucose by the body's cells, particularly in muscle and adipose (fat) tissues, allowing these cells to utilize glucose for energy or store it as glycogen for later use. Additionally, insulin promotes the conversion of excess glucose into fat and inhibits gluconeogenesis, the process through which the liver produces glucose from non-carbohydrate sources. In summary, insulin plays a critical role in regulating blood glucose levels by promoting its utilization and storage, effectively lowering the concentration of glucose in the bloodstream after meals.