How many major glands comprise the endocrine system?

• A. Five
• B. Six
• C. Eight
• D. Seven

Answer: (D)

Endocrine glands release hormones into the bloodstream to regulate growth, metabolism, reproduction, and stress responses. Seven major glands are typically taught: pituitary, thyroid, parathyroid, adrenal, pancreas, pineal, and gonads (ovaries and testes). The pituitary often serves as a master regulator, while the gonads coordinate reproductive hormones. The pineal gland influences sleep-wake cycles, the thyroid sets metabolic rate, the parathyroids manage calcium balance, the adrenals respond to stress, and the pancreas controls blood sugar. Some sources include the hypothalamus or thymus in broader discussions, but in this standard count they’re not listed among the seven. That’s why seven is the commonly referenced total.