D312 ANATOMY AND PHYSIOLOGY I - Set 4 - Part 3

Correct Answer: Thyrotropin-releasing hormone

Option b is correct because thyrotropin-releasing hormone is secreted by the hypothalamus and specifically stimulates thyrotroph cells in the anterior pituitary to produce and release thyroid-stimulating hormone targeting the thyroid gland. Option a is incorrect because corticotropin-releasing hormone stimulates corticotroph cells in the anterior pituitary to produce adrenocorticotropic hormone, which targets the adrenal cortex rather than the thyroid gland. Option c is incorrect because gonadotropin-releasing hormone stimulates gonadotroph cells in the anterior pituitary to produce FSH and LH, which target the reproductive organs rather than the thyroid gland. Option d is incorrect because growth hormone-releasing hormone stimulates somatotroph cells in the anterior pituitary to produce growth hormone, which targets the liver, muscles, and bones rather than the thyroid.

Correct Answer: Growth hormone-inhibiting hormone

Option d is correct because growth hormone-inhibiting hormone is released by the hypothalamus to suppress growth hormone secretion from somatotroph cells, providing a regulatory brake on growth hormone production levels. Option a is incorrect because growth hormone-releasing hormone has the opposite function, stimulating somatotroph cells to increase growth hormone production rather than inhibiting or suppressing its release from the pituitary. Option b is incorrect because prolactin-releasing hormone stimulates lactotroph cells in the anterior pituitary to produce prolactin for mammary gland function, not the inhibition of growth hormone from somatotroph cells. Option c is incorrect because thyrotropin-releasing hormone targets thyrotroph cells to stimulate thyroid-stimulating hormone secretion and has no direct role in inhibiting growth hormone release from somatotroph cells.

Correct Answer: Corticotrophs produce ACTH

Option c is correct because corticotrophs in the anterior pituitary produce adrenocorticotropic hormone, which specifically targets the suprarenal or adrenal cortex to regulate the production of cortisol and other steroid hormones. Option a is incorrect because while somatotrophs do produce growth hormone, this hormone targets the liver, skeletal muscle, and bone for growth rather than the adrenal cortex for cortisol and steroid regulation. Option b is incorrect because while lactotrophs do produce prolactin, this hormone targets the mammary glands for milk production and does not have a regulatory role at the adrenal cortex for steroid hormones. Option d is incorrect because while thyrotrophs do produce thyroid-stimulating hormone, this hormone targets the thyroid gland for T3 and T4 synthesis rather than the adrenal cortex for cortisol production.

Correct Answer: PRH and PIH

Option a is correct because prolactin-releasing hormone stimulates and prolactin-inhibiting hormone suppresses prolactin secretion from lactotroph cells, providing dual regulatory control over prolactin production levels. Option b is incorrect because GHRH and GHIH are the releasing and inhibiting hormones that regulate growth hormone secretion from somatotroph cells, not prolactin release from lactotroph cells in the pituitary. Option c is incorrect because TRH stimulates TSH secretion from thyrotrophs and CRH stimulates ACTH secretion from corticotrophs, and neither of these hormones specifically regulates prolactin release from lactotrophs. Option d is incorrect because GnRH stimulates gonadotroph cells to release FSH and LH, and ACTH is an anterior pituitary hormone rather than a hypothalamic regulatory hormone controlling prolactin secretion.

Correct Answer: Gonadotropin-releasing hormone

Option b is correct because gonadotropin-releasing hormone from the hypothalamus stimulates gonadotroph cells in the anterior pituitary to release both FSH and LH, controlling the reproductive hormone cascade. Option a is incorrect because thyrotropin-releasing hormone stimulates thyrotroph cells to produce thyroid-stimulating hormone targeting the thyroid gland, and it does not regulate reproductive hormone release from gonadotrophs. Option c is incorrect because corticotropin-releasing hormone stimulates corticotroph cells to produce adrenocorticotropic hormone targeting the adrenal cortex, and it has no role in triggering FSH or LH release. Option d is incorrect because prolactin-releasing hormone stimulates lactotroph cells to produce prolactin for mammary gland function and does not influence gonadotroph cells to release reproductive hormones like FSH and LH.

Correct Answer: Paraventricular nucleus

Option d is correct because the paraventricular nucleus of the hypothalamus synthesizes oxytocin, which is transported along neurosecretory axons to the posterior pituitary where it is stored until released for uterine contractions and milk ejection. Option a is incorrect because the supraoptic nucleus primarily synthesizes ADH or vasopressin for water retention at the kidneys, and while the paraventricular nucleus also makes ADH, oxytocin production is its distinguishing role. Option b is incorrect because the anterior pituitary is a separate lobe that manufactures its own hormones through five endocrine cell types and does not synthesize the hormones stored in the posterior pituitary. Option c is incorrect because the choroid plexus is the structure responsible for producing cerebrospinal fluid within the brain ventricles and has no role in synthesizing oxytocin or any other pituitary hormone.

Correct Answer: ADH from supraoptic nucleus

Option c is correct because ADH or vasopressin is synthesized primarily in the supraoptic nucleus and acts on kidney collecting ducts to promote water retention while also causing mild vasoconstriction in blood vessels. Option a is incorrect because oxytocin targets the pregnant uterus for contractions and mammary glands for milk ejection, and it does not act on kidney collecting ducts to promote water retention or vasoconstriction. Option b is incorrect because prolactin is produced by lactotroph cells in the anterior pituitary and targets mammary glands for milk production, having no direct role in kidney water retention or blood vessel tone. Option d is incorrect because growth hormone is produced by somatotroph cells in the anterior pituitary and targets bones, muscles, and liver for growth, not kidney collecting ducts for water retention or vasoconstriction.

Correct Answer: Corpus luteum

Option a is correct because the corpus luteum is a mass of cells that forms in the ovary after ovulation and produces progesterone, which is essential for maintaining the uterine lining during early pregnancy. Option b is incorrect because seminiferous tubules are found in the testes and serve as the site of spermatogenesis where male germ cells develop, not a structure that forms in the ovary after ovulation. Option c is incorrect because the pituitary gland is located below the thalamus in the brain and regulates many endocrine functions but does not form as a temporary structure in the ovary after ovulation. Option d is incorrect because the adrenal cortex is the outer portion of the adrenal gland located above the kidneys and produces cortisol and other steroid hormones, not the progesterone-producing ovarian structure.

Correct Answer: LH has more specific targets

Option c is correct because luteinizing hormone has specific targets, triggering ovulation in the ovaries and testosterone secretion in the testes, while FSH has a broader target affecting the gonads more generally. Option a is incorrect because FSH targets the gonads broadly including both the ovaries and the testes, not exclusively the testes, as it plays roles in egg development and sperm production across both sexes. Option b is incorrect because it is LH rather than FSH that specifically triggers ovulation in females, while FSH promotes follicle development and maturation in the ovaries as part of the reproductive cycle. Option d is incorrect because LH has more specific and targeted actions at the ovaries and testes, while it is FSH that targets the gonads more broadly to support overall gamete development in both sexes.

Correct Answer: Seminiferous tubules

Option d is correct because the seminiferous tubules are the specific site within the testes where spermatogenesis occurs, with germ cells developing into mature sperm under hormonal regulation through the hypothalamic-pituitary-gonadal axis. Option a is incorrect because the corpus luteum is a structure that forms in the ovary after ovulation and produces progesterone during early pregnancy, and it is not found in the testes or involved in sperm production. Option b is incorrect because the paraventricular nucleus is a region of the hypothalamus that synthesizes oxytocin and ADH for the posterior pituitary, not a testicular structure where spermatogenesis takes place. Option c is incorrect because the adrenal medulla is the inner portion of the adrenal gland that produces epinephrine and norepinephrine during stress responses, not a reproductive structure involved in sperm cell development.