Question 435 of 782

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

  • Cortisol
  • Insulin
  • Glucagon
  • Adrenaline

Correct Answer: B

Explanation
Correct Option: B. Insulin Detailed Explanation:
  1. Understanding Blood Glucose Regulation:
  2. Blood glucose levels are crucial for maintaining energy homeostasis in the body. The body needs to keep these levels within a narrow range to ensure that cells have enough energy to function properly.
  3. The pancreas plays a key role in regulating blood glucose levels through the secretion of hormones, primarily insulin and glucagon.
  4. Role of Insulin:
  5. Insulin is a peptide hormone produced by the beta cells of the islets of Langerhans in the pancreas.
  6. When blood glucose levels rise after eating (postprandial state), insulin is released into the bloodstream.
  7. Insulin facilitates the uptake of glucose by various cells, particularly muscle and fat cells, by promoting the translocation of glucose transporter proteins (like GLUT4) to the cell membrane. This allows glucose to enter the cells, where it can be used for energy or stored as glycogen.
  8. Mechanism of Action:
  9. Once insulin binds to its receptor on the target cell, it triggers a signaling cascade that results in the movement of glucose transporters to the cell surface.
  10. This process not only lowers blood glucose levels but also promotes the storage of glucose as glycogen in the liver and muscle tissues and inhibits gluconeogenesis (the production of glucose from non-carbohydrate sources).
  11. Why Other Options Are Incorrect:
  12. A. Cortisol:
    • Cortisol is a steroid hormone produced by the adrenal glands and is primarily involved in the stress response. It increases blood glucose levels by promoting gluconeogenesis and inhibiting glucose uptake in non-essential tissues. Therefore, it has the opposite effect of insulin.
  13. C. Glucagon:
    • Glucagon is another hormone produced by the alpha cells of the pancreas. It is released when blood glucose levels are low and works to increase blood glucose levels by stimulating glycogenolysis (the breakdown of glycogen to glucose) and gluconeogenesis. Thus, glucagon acts to raise blood glucose levels, counteracting the effects of insulin.
  14. D. Adrenaline:
    • Adrenaline (or epinephrine) is a hormone released during the "fight or flight" response. It increases blood glucose levels by promoting glycogenolysis and inhibiting insulin secretion. While it plays a role in acute stress responses, it is not primarily responsible for the regulation of blood glucose levels in a normal physiological state.
Summary of Key Points:
  • Insulin is the primary hormone responsible for lowering blood glucose levels by promoting glucose uptake into cells.
  • It is secreted by the pancreas in response to high blood glucose levels, especially after meals.
  • Other hormones like cortisol, glucagon, and adrenaline have roles in increasing blood glucose levels or responding to stress, but they do not promote glucose uptake like insulin does.
  • Understanding the balance between these hormones is crucial for comprehending metabolic processes and conditions like diabetes.
Revision Summary:
  • Insulin promotes glucose uptake into cells, lowering blood glucose levels.
  • Cortisol and glucagon increase blood glucose levels, counteracting insulin.
  • Adrenaline raises blood glucose during stress but is not a primary regulator.
  • The pancreas is central to glucose homeostasis through the secretion of these hormones.
← Previous Next →
Jump to: 435 436 437 438 439 440 441 442 443 444