Which of the following hormones is not directly involved in blood glucose regulation?

• A. Insulin.
• B. Cortisol.
• C. Norepinephrine.
• D. Thyroxine.

Answer: (D)

Verified step by step guidance

1. Understand the role of each hormone listed in the problem and how they relate to blood glucose regulation.
2. Recall that insulin is a hormone produced by the pancreas that lowers blood glucose levels by facilitating the uptake of glucose into cells.
3. Recognize that cortisol, a hormone released by the adrenal glands, is involved in increasing blood glucose levels during stress by stimulating gluconeogenesis (the production of glucose from non-carbohydrate sources).
4. Identify that norepinephrine, also released by the adrenal glands, plays a role in the fight-or-flight response and can increase blood glucose levels by stimulating glycogenolysis (the breakdown of glycogen into glucose).
5. Note that thyroxine, a hormone produced by the thyroid gland, primarily regulates metabolism and basal metabolic rate but is not directly involved in the regulation of blood glucose levels.