Which gland is commonly called the master gland?

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

Answer: (A)

The main idea is how the pituitary gland acts as the control hub of the body's endocrine system. It releases a suite of hormones that stimulate other glands to produce their own hormones—for example, thyroid-stimulating hormone tells the thyroid to make thyroid hormones, adrenocorticotropic hormone prompts the adrenal cortex to release cortisol, and hormones like luteinizing hormone and follicle-stimulating hormone regulate the ovaries and testes. Growth hormone influences growth in bones and tissues, while prolactin affects milk production. The pituitary’s activity is guided by releasing and inhibiting signals from the hypothalamus, and the posterior part stores hormones made in the hypothalamus (such as oxytocin and vasopressin). Because it coordinates the activity of several other glands, it’s commonly called the master gland.

The other glands don’t play this broad regulatory role. The thyroid mainly produces hormones that control metabolism, not a broad set of downstream glands. The pineal gland mainly secretes melatonin to help regulate sleep-wake cycles. The adrenal glands respond to pituitary signals and secrete their own hormones, but they don’t regulate other endocrine glands themselves.