Question

The C cells of the thyroid gland are responsible for the secretion of which hormone?

• A. $T_3$ and $T_4$
• B. Calcitonin
• C. Both thyroxine and calcitonin
• D. TSH

Answer 1

The correct option is B Calcitonin

C cells, also known as parafollicular cells of the thyroid gland, are responsible for the synthesis, storage and secretion of the hormone calcitonin. This hormone, along with the parathyroid hormone, regulates the blood calcium levels. When blood calcium levels increase above the normal, C cells secrete the calcitonin hormone, which decreases the blood calcium level and moves the calcium from the blood to bones. Therefore, it is a hypocalcemic hormone.

The thyroid glands also have follicular cells, which secrete the hormone thyroxine ($T_4$) and triiodothyronine ($T_3$). $T_3$ and $T_4$ play a major role in controlling the basal metabolic rate of the body.

TSH is secreted by the anterior pituitary. It stimulates the thyroid to produce $T_3$ and $T_4$.