Question 431 of 782

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

  • Glucagon
  • Insulin
  • Adrenaline
  • Cortisol

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. When we consume food, especially carbohydrates, glucose enters the bloodstream, leading to an increase in blood glucose levels.
  3. The body has a sophisticated system to regulate these levels, primarily involving hormones produced by the pancreas.
  4. Role of Insulin:
  5. Insulin is a peptide hormone produced by the beta cells of the islets of Langerhans in the pancreas. Its primary function is to lower blood glucose levels.
  6. When blood glucose levels rise (for example, after eating), insulin is secreted into the bloodstream. It facilitates the uptake of glucose by various cells, particularly muscle and fat cells, allowing them to use glucose for energy or store it as glycogen for later use.
  7. Insulin also inhibits gluconeogenesis (the production of glucose from non-carbohydrate sources) and promotes lipogenesis (the conversion of glucose into fat), further helping to lower blood glucose levels.
  8. Why Other Options Are Incorrect:
  9. 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 promoting glucose uptake into cells; rather, it works to increase blood glucose levels when they are low.
  10. C. Adrenaline:
    • Adrenaline (or epinephrine) is a hormone released during stress or "fight or flight" situations. It increases blood glucose levels by stimulating glycogenolysis and inhibiting insulin secretion. While it plays a role in energy mobilization, it does not promote glucose uptake into cells; instead, it prepares the body for immediate energy needs.
  11. D. Cortisol:
    • Cortisol is a steroid hormone released in response to stress and low blood glucose levels. It promotes gluconeogenesis and the breakdown of proteins and fats to increase blood glucose levels. Like adrenaline, cortisol does not facilitate glucose uptake into cells; it works to increase glucose availability during stress.
Summary of Key Points:
  • Insulin is the primary hormone responsible for lowering blood glucose levels by promoting glucose uptake into cells.
  • Glucagon raises blood glucose levels, counteracting insulin's effects.
  • Adrenaline and cortisol also increase blood glucose levels but do not promote glucose uptake into cells.
  • Understanding the roles of these hormones is crucial for grasping how the body maintains energy balance and responds to varying glucose levels.
Revision Summary:
  • Insulin lowers blood glucose by promoting cellular uptake of glucose.
  • Glucagon raises blood glucose by stimulating glycogen breakdown.
  • Adrenaline and cortisol increase blood glucose but do not facilitate glucose uptake.
  • The balance between these hormones is essential for metabolic homeostasis.
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