Which gland is referred to as the 'master gland'?

• A. Exocrine
• B. Pituitary
• C. Adrenal
• D. Thyroid

Answer: (B)

The main idea is identifying which gland coordinates the activity of other endocrine glands. The pituitary acts as the master regulator because it releases several tropic hormones that stimulate other glands to secrete their hormones. For instance, thyroid-stimulating hormone prompts the thyroid to release thyroid hormones; adrenocorticotropic hormone stimulates the adrenal cortex; and gonadotropins (FSH and LH) act on the ovaries and testes. These pituitary hormones are themselves controlled by releasing and inhibiting signals from the hypothalamus, placing the pituitary at the top of the endocrine control system. In contrast, the adrenal and thyroid glands are target glands, not regulators of other glands, and exocrine glands secrete into ducts rather than into the bloodstream.