Chapter 18: The Endocrine System — Pituitary & Hypothalamus (Lecture 2 of 4)

Vocabulary flashcards covering hypothalamus and pituitary concepts from the lecture. Topics include hypothalamic control, pituitary structure, key hormones, and basic regulatory mechanisms.

Hypothalamus

Master endocrine gland that integrates CNS input (cortex, thalamus, autonomic) and produces releasing/inhibiting hormones; controls the anterior pituitary and stores two hormones in the posterior pituitary.

Infundibulum

Stalk that connects the hypothalamus to the pituitary, through which hormones and signals pass.

Hypophyseal portal system

Vascular network that carries hypothalamic releasing and inhibiting hormones to the anterior pituitary.

Anterior pituitary (adenohypophysis)

Front lobe of the pituitary that secretes 7 hormones; regulated by hypothalamic releasing/inhibiting hormones via the portal system; comprises about 75% of pituitary weight.

Posterior pituitary (neurohypophysis)

Back lobe of the pituitary that stores and releases two hypothalamic hormones; made of neural tissue and does not synthesize its own hormones.

Neurosecretory cells

Hypothalamic neurons that synthesize hormones, package them into vesicles, and transport them to the pituitary for release.

Releasing hormone (general)

Hypothalamic hormones that stimulate secretion of anterior pituitary hormones.

Inhibiting hormone (general)

Hypothalamic hormones that suppress secretion of anterior pituitary hormones.

Growth hormone-releasing hormone (GHRH)

Stimulates release of growth hormone from somatotrophs in the anterior pituitary.

Growth hormone-inhibiting hormone (GHIH; somatostatin)

Inhibits release of growth hormone from somatotrophs.

Thyrotropin-releasing hormone (TRH)

Stimulates release of thyroid-stimulating hormone from thyrotrophs.

Gonadotropin-releasing hormone (GnRH)

Stimulates release of FSH and LH from gonadotrophs.

Corticotropin-releasing hormone (CRH)

Stimulates release of ACTH from corticotrophs.

Prolactin-releasing hormone (PRH)

Stimulates release of prolactin from lactotrophs.

Prolactin-inhibiting hormone (PIH)

Dopamine; inhibits prolactin release from lactotrophs.

Oxytocin

Posterior pituitary hormone that stimulates uterine contractions and milk ejection; released during delivery and nursing.

Antidiuretic hormone (ADH) / vasopressin

Promotes water reabsorption in kidneys and constricts arterioles; alcohol can inhibit its secretion.

Growth Hormone (GH)

Secreted by somatotrophs; promotes growth, metabolism, and lipolysis; acts directly and via IGF; released in bursts.

Thyroid-stimulating hormone (TSH)

Stimulates thyroid to produce T3/T4; regulated by TRH; negative feedback by T3/T4.

Follicle-stimulating hormone (FSH)

Stimulates ovarian follicle development and estrogen secretion; stimulates spermatogenesis; regulated by GnRH; inhibited by estrogen (females) or testosterone (males).

Luteinizing hormone (LH)

Triggers ovulation and corpus luteum formation; stimulates estrogen and progesterone secretion in females; stimulates testosterone production in males.

Prolactin (PRL)

Promotes milk production in the mammary glands; regulated by PRH and PIH; suckling reduces PIH; pregnancy increases PRH.

Adrenocorticotropic hormone (ACTH)

Stimulates adrenal cortex to produce cortisol and other glucocorticoids; CRH stimulates; glucocorticoids provide negative feedback.

Melanocyte-stimulating hormone (MSH)

Produced by corticotrophs; influences melanin production; role in humans is limited.