Which gland regulates metabolism via hormones like thyroxine?

• A. Thyroid gland
• B. Adrenal gland
• C. Pineal gland
• D. Hypothalamus

Answer: (A)

Metabolism is governed by hormones that set the rate at which the body uses energy. Thyroxine, produced by the thyroid gland, is a key driver of this process by increasing basal metabolic rate, heat production, and the overall utilization of carbohydrates and fats. The thyroid’s activity is controlled by a signaling pathway involving the hypothalamus and pituitary: the hypothalamus releases TRH, which prompts the pituitary to release TSH, and TSH then stimulates the thyroid to produce T4 and T3. As T4 and T3 rise, they feedback to dampen TRH and TSH production, balancing the system. This makes the thyroid gland the primary organ regulating metabolism through thyroxine. Other glands influence metabolism in different ways—for example, adrenal hormones affect energy mobilization during stress, but thyroxine is specifically tied to the thyroid.