Pituitary gland is endocrine gland connected to hypothalamus at the base of the brain. It secretes many hormones.
(a) It is called as master endocrine gland.
(b) Its anterior part is neurohypophysis a

Question

Pituitary gland is endocrine gland connected to hypothalamus at the base of the brain. It secretes many hormones.
(a) It is called as master endocrine gland.
(b) Its anterior part is neurohypophysis and posterior is adenohypophysis.
(c) Oxytocin and Vasopressin are secreted by posterior pituitary.
(d) STH, TSH, ACTH are secreted by adenohypophysis.
Which of the statements given above is/are correct ?

UnlockIAS · Accepted Answer

Correct — option (2), only statements (a) and (c). Statement (a) is correct. The pituitary, or hypophysis, is a pea-sized gland lying in a bony hollow at the base of the skull and joined to the hypothalamus above it by a short stalk, and it is called the master endocrine gland because several of the hormones it releases do not act on ordinary tissue at all but on other endocrine glands, driving the thyroid, the cortex of the adrenal glands and the gonads to release their own hormones. Statement (c) is correct as well. Oxytocin and vasopressin are released into the blood from the posterior pituitary; oxytocin causes the contraction of the smooth muscle of the uterus during childbirth and the ejection of milk from the mammary glands, while vasopressin, also called the antidiuretic hormone, acts on the kidney tubules to reabsorb water and so to concentrate the urine, its failure producing the condition known as diabetes insipidus. There is a refinement worth knowing about statement (c): these two hormones are actually manufactured by nerve cells in the hypothalamus and travel down the axons of those cells into the posterior lobe, which stores them and releases them on demand — so the posterior pituitary is more a store and a release point than a factory, which is why it is described as nervous tissue rather than glandular tissue. Statement (b) is plainly wrong, and it is the statement the question is built on. It reverses the two lobes. The anterior part of the pituitary is the adenohypophysis, the name meaning glandular hypophysis, and the posterior part is the neurohypophysis, the name meaning nervous hypophysis; the statement puts them the other way round. That single error disposes of option (4), which is the only other option containing statement (b), and the correctness of statement (a) disposes of option (3), which would require statement (a) to be false. The choice then lies between option (1) and option (2), and the two differ only in whether statement (d) is counted among the correct statements. The Commission's final key gives option (2), and this card is written to that key: statement (d) is not among the statements the key counts as correct, so the answer is only (a) and (c). Students should nevertheless learn the underlying physiology in the form the textbooks give it, and there the position is that the hormones named by their initials in statement (d) — the somatotropic or growth hormone, the thyroid-stimulating hormone and the adrenocorticotropic hormone — are products of the anterior lobe, the adenohypophysis, along with prolactin and the two gonadotropins. Reading the list of statements as a single connected description, in which statement (d) inherits the definition of the adenohypophysis that statement (b) has just given, is the reading on which the exclusion of statement (d) follows, and it is a reminder that in a linked statement list an error planted early can carry into what comes after it. The answer to be marked is option (2).

Why the other options are wrong — (a) This option adds statement (d) to the two statements the key counts as correct, and it is the option that most candidates who miss this question will have chosen, because the hormones named in statement (d) are indeed taught as anterior lobe products. It is not the keyed answer: the Commission's final key gives option (2), which counts only statements (a) and (c), and a card written against a live paper follows the published key. What can usefully be taken from the option is the content of statement (d) itself, which is worth learning whichever way the item is marked. The somatotropic hormone, better known as growth hormone, governs the growth of the long bones and the soft tissues, its excess in childhood producing gigantism and in adulthood acromegaly, and its deficiency in childhood producing pituitary dwarfism. The thyroid-stimulating hormone drives the thyroid to release thyroxine, and the adrenocorticotropic hormone drives the cortex of the adrenal gland to release its steroid hormones.  (c) This option requires statements (a) and (c) to be false, and neither of them is. The pituitary is called the master endocrine gland in every standard account, precisely because its tropic hormones control the thyroid, the adrenal cortex and the gonads, and although modern physiology adds that the pituitary is itself directed by the hypothalamus through releasing and inhibiting hormones carried in a special portal system of blood vessels, that refinement qualifies the title rather than withdrawing it. Oxytocin and vasopressin are likewise correctly assigned to the posterior lobe, which stores them and releases them into the blood. An option that rejects two well-established statements in order to keep a third is a poor bargain in this format, and the general rule is to eliminate first on the statement you are most certain about, which here is the reversal in statement (b) and the plain correctness of statement (c).  (d) This option contains statement (b), and statement (b) is the one clear error in the list: it calls the anterior part the neurohypophysis and the posterior part the adenohypophysis, which is exactly the wrong way round. The correct assignment is fixed by the names themselves, and it is worth learning them through their meanings rather than as arbitrary labels. Adeno- refers to a gland, and the anterior lobe is true glandular tissue that manufactures and secretes its own hormones under instruction from the hypothalamus. Neuro- refers to nerve tissue, and the posterior lobe is an outgrowth of the brain consisting largely of the nerve endings of hypothalamic cells, which is why it stores and releases hormones made elsewhere rather than making its own. Any option containing statement (b) can be struck out on sight, and doing so first is the quickest way into this question.

Concept: The pituitary gland is a small structure at the base of the brain, lodged in a bony depression of the sphenoid bone and connected to the hypothalamus by a stalk, and it is divided into two parts of quite different origin and behaviour. The anterior lobe, the adenohypophysis, is glandular tissue and manufactures its own hormones: growth hormone, also called the somatotropic hormone; prolactin, which drives the formation of milk; the thyroid-stimulating hormone, which acts on the thyroid; the adrenocorticotropic hormone, which acts on the cortex of the adrenal gland; and the two gonadotropins, the follicle-stimulating hormone and the luteinising hormone, which act on the ovaries and the testes. Its activity is controlled by the hypothalamus, which sends releasing and inhibiting hormones to it through a dedicated system of blood vessels. The posterior lobe, the neurohypophysis, is nervous tissue, an extension of the hypothalamus rather than a gland in its own right; oxytocin and vasopressin are synthesised in hypothalamic nerve cells, carried down their axons into this lobe and stored there until they are released into the circulation. The disorders associated with the gland are examined as often as its hormones: excess growth hormone gives gigantism in the growing years and acromegaly after growth has stopped, deficiency gives pituitary dwarfism, and a failure of vasopressin gives diabetes insipidus, in which large volumes of dilute urine are passed.

State PCS 2022 Q48 — Science & Technology PYQ with Answer

State PCS 2022 Q48 — Science & Technology PYQ with Answer