Q30
General ScienceBiology
Which of the following pairs comprises of the smallest and the largest endocrine glands of human respectively?
- a.Pituitary-thyroid
- b.Thyroid-pituitary
- c.Pineal body-ovary
- d.Pineal body-thyroid
Answer: (D) Pineal body-thyroid
The pineal body (epiphysis), a pea-sized structure in the brain weighing only about 0.1–0.2 g, is the smallest endocrine gland; it secretes melatonin, which regulates the sleep–wake cycle. The thyroid, in the neck and weighing about 25–30 g, is the largest purely endocrine gland; it secretes thyroxine (T4) and T3, which need iodine, and calcitonin. The pituitary (about 0.5 g) is called the master gland but is neither the smallest nor the largest, and the ovary is a gonad with a secondary endocrine role. Do not confuse this with the liver, which is the largest gland of the body overall, or the pancreas, a mixed (heterocrine) gland.