CDS (I) 2020 General Knowledge · Question 28 of 120

Correct — B, Pituitary. The pituitary is a single gland on the midline. It hangs from the base of the brain below the hypothalamus and sits in the sella turcica, a hollow in the sphenoid bone, and it is roughly the size and shape of a kidney bean, about a centimetre across. The other three glands on the list come in pairs, because they are bilateral organs. The adrenals sit one above each kidney, and the gonads — testes in males and ovaries in females — are a pair in each case. So the pituitary is the only unpaired gland named here.

• (a)Adrenal — Paired. One adrenal gland caps each kidney, which is why they are also called the suprarenal glands.
• (c)Testis — Paired. The two testes are both endocrine, secreting testosterone, and exocrine, releasing sperm through a duct.
• (d)Ovary — Paired. The two ovaries secrete oestrogen and progesterone as well as releasing eggs.

Endocrine glands are ductless and release hormones straight into the blood. The pituitary is called the master gland because four of its six anterior hormones are tropic — they control other endocrine organs, including the thyroid, the adrenal cortex and the gonads. It is itself directed by the hypothalamus above it, and it has two functional parts: an anterior lobe that makes and secretes its own hormones, and a posterior lobe that stores and releases hormones made in the hypothalamus.

Anatomy answers this before endocrinology does. Bilateral organs come in pairs, and midline structures sitting on or under the brain do not — a rule that also disposes of the thyroid, the pineal and the pancreas if they turn up in a variant of this question. The pituitary is the only one of the four named glands that is a single midline structure. Worth guarding against is the reflex that the pituitary must be plural because it has an anterior and a posterior lobe; those are two parts of one gland, joined by a small intermediate lobe that is almost absent in humans.

• The pituitary is a single gland at the base of the brain, seated in the sella turcica of the sphenoid bone.
• It measures about 1 cm across and weighs roughly half a gram to a gram.
• It has an anterior lobe that produces its own hormones and a posterior lobe that releases hormones made in the hypothalamus.
• Adrenal glands are paired, one above each kidney, and are also called the suprarenal glands.
• Four of the six anterior pituitary hormones are tropic hormones that regulate other endocrine glands.

• Treating the anterior and posterior lobes as two glands.
• Forgetting that testes and ovaries count as endocrine glands, not merely reproductive organs.
• Assuming that only the pituitary is unpaired; the thyroid, pineal and pancreas are single too.

As paired against unpaired glands, as a gland-to-hormone match, or through a named disorder and the gland behind it.

• practice — not a real PYQ

  The pituitary gland is located

  • (a)above each kidney
  • (b)at the base of the brain
  • (c)in the neck, in front of the windpipe
  • (d)behind the stomach

  Answer(b) at the base of the brain — hanging below the hypothalamus and seated in the sella turcica of the sphenoid bone.

• practice — not a real PYQ

  Which one of the following glands is both an endocrine and an exocrine gland?

  • (a)Pituitary
  • (b)Thyroid
  • (c)Pancreas
  • (d)Pineal

  Answer(c) Pancreas — it releases digestive juice through a duct and secretes insulin and glucagon into the blood.