Question

Name the hormone which controls the basal metabolic rate in animals.

• A. Adrenaline
• B. Thyroxine
• C. Aldosterone
• D. Oxytocin

Answer 1

Answer: (B)

Thyroxine

Thyroxine is the main hormone secreted into the bloodstream by the thyroid gland. It plays vital roles in digestion, heart and muscle function, brain development and maintenance of bones.

Thyroid hormones play vital roles in regulating the body’s metabolic rate, heart and digestive functions, muscle control, brain development and maintenance of bones. The production and release of thyroid hormones, thyroxine and triiodothyronine, is controlled by a feedback loop system which involves the hypothalamus in the brain and the pituitary and thyroid glands. The hypothalamus secretes thyrotropin-releasing hormone which, in turn, stimulates the pituitary gland to produce thyroid stimulating hormone. This hormone stimulates the production of the thyroid hormones, thyroxine and triiodothyronine, by the thyroid gland.

This hormone production system is regulated by a negative feedback loop so that when the levels of the thyroid hormones, thyroxine and triiodothyronine increase, they prevent the release of both thyrotropin-releasing hormone and thyroid stimulating hormone. This system allows the body to maintain a constant level of thyroid hormones in the body.