Question 421 of 782

Which hormone is primarily responsible for regulating blood glucose levels by promoting the uptake of glucose into cells?

  • Adrenaline
  • Insulin
  • Glucagon
  • Thyroxine

Correct Answer: B

Explanation
Correct Option: B. Insulin Detailed Explanation:
  1. Understanding Blood Glucose Regulation:
  2. Blood glucose levels are crucial for maintaining energy balance in the body. The body needs to keep these levels within a narrow range to ensure that cells receive enough glucose for energy while preventing damage from excessively high or low glucose levels.
  3. Role of Insulin:
  4. Insulin is a hormone produced by the beta cells of the pancreas. Its primary function is to lower blood glucose levels by facilitating the uptake of glucose into cells, particularly muscle and fat cells. When you eat, carbohydrates are broken down into glucose, which enters the bloodstream. In response, the pancreas releases insulin.
  5. Insulin binds to insulin receptors on the surface of cells, triggering a series of events that allow glucose transporters (specifically GLUT4) to move to the cell membrane. This process increases the uptake of glucose from the blood into the cells, where it can be used for energy or stored as glycogen.
  6. Why Other Options Are Incorrect:
  7. A. Adrenaline:
    • Adrenaline (also known as epinephrine) is a hormone released during stress or "fight or flight" situations. It increases blood glucose levels by promoting glycogenolysis (the breakdown of glycogen to glucose) in the liver and inhibiting insulin secretion. Thus, it works to raise blood glucose levels rather than lower them.
  8. C. Glucagon:
    • Glucagon is another hormone produced by the pancreas, specifically by the alpha cells. Its primary role is to increase blood glucose levels by stimulating glycogenolysis and gluconeogenesis (the production of glucose from non-carbohydrate sources) in the liver. It acts in opposition to insulin, making it a key player in raising blood glucose levels rather than promoting glucose uptake.
  9. D. Thyroxine:
    • Thyroxine (T4) is a hormone produced by the thyroid gland that primarily regulates metabolism and energy expenditure. While it does have some influence on glucose metabolism, it does not directly regulate blood glucose levels like insulin does. Its main role is to increase the basal metabolic rate and influence overall energy levels in the body.
Summary of Key Points:
  • Insulin is the primary hormone responsible for lowering blood glucose levels by promoting glucose uptake into cells.
  • Adrenaline and glucagon both work to increase blood glucose levels, counteracting the effects of insulin.
  • Thyroxine influences metabolism but does not directly regulate blood glucose levels.
  • Understanding the roles of these hormones is crucial for grasping how the body maintains glucose homeostasis.
Revision Summary:
  • Insulin promotes glucose uptake into cells, lowering blood glucose levels.
  • Adrenaline and glucagon increase blood glucose levels, opposing insulin's action.
  • Thyroxine regulates metabolism but does not directly affect blood glucose.
  • The balance between insulin and glucagon is essential for maintaining stable blood glucose levels.
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