pt 2: Hypothalamus + Pituitary (Anterior & Posterior)

Hypothalamus function

Controls pituitary gland through releasing and inhibiting hormones

Pituitary gland

Master gland with anterior (glandular) and posterior (neural) lobes

Hypothalamic-hypophyseal tract

Neural connection carrying ADH & oxytocin to posterior pituitary

Hypophyseal portal system

Blood vessel network carrying releasing hormones to anterior pituitary

Posterior pituitary

Stores and releases ADH and oxytocin made in hypothalamus

ADH function

Increases water reabsorption in kidneys; raises blood pressure

Oxytocin function

Stimulates uterine contractions, milk ejection, and bonding

Anterior pituitary hormones

TSH, ACTH, FSH, LH, GH, PRL

TSH function

Stimulates thyroid to release T3 and T4

TRH function

Released by hypothalamus to stimulate TSH

ACTH function

Stimulates adrenal cortex to release cortisol

CRH function

Released from hypothalamus to stimulate ACTH; increases in stress

GH function

Stimulates growth, protein synthesis, fat breakdown

GHRH function

Stimulates GH release

Somatostatin (GHIH)

Inhibits GH release

Effects of GH on metabolism

Increases fat breakdown, increases glucose, promotes growth

FSH function

Stimulates gamete production (sperm/eggs)

LH function

Triggers ovulation, estrogen/progesterone release; testosterone in males

GnRH function

Released by hypothalamus to stimulate FSH & LH

Prolactin (PRL)

function Stimulates milk production

Dopamine (PIH)

Inhibits prolactin release

Regulation of prolactin

Decreased dopamine → increased PRL

Hypothalamic control of anterior pituitary

Releasing/inhibiting hormones travel via portal circulation

Stress effect on CRH

Stress increases CRH → ACTH → cortisol

Feedback loop for TSH

Too much T3/T4 → inhibit TRH & TSH

Feedback loop for cortisol

High cortisol → inhibits CRH & ACTH

Hypersecretion of GH in adults

Acromegaly

Hypersecretion of GH in children

Gigantism

Hyposecretion of GH

Dwarfism

Posterior pituitary does not make hormones

It only stores and releases ADH & oxytocin