Which hormone, produced by the pancreas, is primarily responsible for lowering blood glucose levels after a meal?
Glucagon
Insulin
Cortisol
Adrenaline
Correct Answer:B
Explanation
Correct Option: B. Insulin
Detailed Explanation:
Understanding Blood Glucose Regulation:
After a meal, the carbohydrates in the food are broken down into glucose, which enters the bloodstream. This increase in blood glucose levels signals the pancreas to release insulin.
Insulin is a hormone produced by the beta cells of the islets of Langerhans in the pancreas. Its primary role is to help lower blood glucose levels.
Mechanism of Action of Insulin:
Facilitating Glucose Uptake: Insulin promotes the uptake of glucose by cells, particularly muscle and fat cells. It does this by signaling these cells to increase the number of glucose transporters (GLUT4) on their surfaces, allowing more glucose to enter the cells.
Stimulating Glycogenesis: Insulin encourages the liver and muscle cells to convert glucose into glycogen (a storage form of glucose) through a process called glycogenesis. This helps to reduce the amount of glucose in the bloodstream.
Inhibiting Gluconeogenesis: Insulin also inhibits gluconeogenesis, which is the process of producing glucose from non-carbohydrate sources in the liver. By doing this, insulin further helps to lower blood glucose levels.
Why Other Options Are Incorrect:
A. Glucagon:
Glucagon is produced by the alpha cells of the pancreas and has the opposite effect of insulin. It raises blood glucose levels by promoting glycogenolysis (the breakdown of glycogen into glucose) and gluconeogenesis. Therefore, glucagon is not responsible for lowering blood glucose levels after a meal.
C. Cortisol:
Cortisol is a steroid hormone produced by the adrenal glands and is involved in the stress response. It increases blood glucose levels by promoting gluconeogenesis and inhibiting glucose uptake in non-essential tissues. Thus, it does not lower blood glucose levels.
D. Adrenaline (Epinephrine):
Adrenaline is also produced by the adrenal glands and is part of the body's fight-or-flight response. It increases blood glucose levels by stimulating glycogenolysis and gluconeogenesis. Like cortisol, it does not lower blood glucose levels.
Summary of Key Points:
Insulin is the primary hormone responsible for lowering blood glucose levels after meals.
It facilitates glucose uptake by cells, stimulates glycogen formation, and inhibits glucose production.
Glucagon, cortisol, and adrenaline all work to increase blood glucose levels, making them incorrect options for this question.
Revision Summary:
Insulin lowers blood glucose levels by promoting glucose uptake and storage.
Glucagon, cortisol, and adrenaline increase blood glucose levels.
Insulin is secreted in response to high blood glucose levels after meals.
Understanding the roles of these hormones is crucial for grasping metabolic processes in the body.