Which gland is often referred to as the master gland?

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

Answer: (D)

The question tests understanding of which gland acts as the master regulator of the endocrine system. The pituitary gland earns that title because its anterior lobe releases several tropic hormones that set other glands into action. For example, it secretes thyroid-stimulating hormone to prompt the thyroid to make thyroid hormones, adrenocorticotropic hormone to stimulate the adrenal cortex, and gonadotropins (FSH and LH) to drive the ovaries or testes. It also produces growth hormone that influences tissues throughout the body and prolactin for milk production. The pituitary sits at the base of the brain and is regulated by the hypothalamus through a portal system, which lets the hypothalamus finely tune when and how much the pituitary releases its hormones. The posterior pituitary stores and releases hormones made in the hypothalamus (like ADH and oxytocin), but the key role in driving other glands lies with the anterior pituitary. The thyroid, adrenal, and pineal glands are primarily targets of pituitary hormones or other systems, not the central regulator.