Pituitary Gland Flashcards
Embryonic development of pituitary gland
- brain grow down, roof of mouth grow up
- roof of mouth = Rathke’s Pouch (pituitary gland)
- anterior and posterior lobe
Structure of Pituitary Gland
Pars Nervosa (axons)
Pars Intermedia (btwn lobes)
Pars Distalis (epithelial cells)
Pars Tuberalis (around stalk)
Infundibulum = median eminence + infundibular process
Hypothalamus structures that innervate pituitary gland
paraventricular + supraoptic nucleus = make hormones released in pars nervosa
hypothalamo-hypophysiotropic nuclei = make trophic hormones to control activities of pars distalis (acidophils and basophils)
Blood Supply of pituitary gland
superior hypophysial artery = for pars distalis
inferior hypophysial artery = for nervosa
primary capillary plexus in median eminence
secondary capillary plexus in pars distalis
capillary plexus in pars nervosa
Hormones made in pituitary gland
Pars Nervosa = oxytocin, ADH
Pars Distalis
- Basophils
— ACTH (corticotrophs), TSH (thyrotrophs)
— FSH, LH (gonadotrophs)
- Acidophils
— Prolactin (mammotrophs) GH (somatotrophs)
- Chromophobes – released contents
Basophilic Gonadotrophs
FSH (follicular cells, sertoli cells) = inhibin + activin
LH = (corpus luteum, Leydig cell)
Inhibin shut off gonadotrophs
GnRH and Activin stimulate gonadotrophs
Basophilic Thyrotrophs
TSH = stimulate production of T3/T4 by thyroid gland
T3 shut off TRH
TRH stimulate thyrotrophs
Basophillic Corticotrophs
ACTH = aldosterone, androgens, cortisol (adrenal gland)
Cortisol shut off CRH
CRH stimulate corticotrophs
- stress, low cortisol, vasopressin
Acidophilic Somatotrophs
GH = liver produce IGF-1 = hypertrophy of chondrocytes in long bones
IGF-1 shut off GHRH
Somatostatin shut off somatotrophs
GHRH stimulate somatotrophs
Acidophilic Mammotrophs
Prolactin = lactation
Dopamine shut off prolactin release
Prolactin Releasing Factor stimulate mammotrophs
Cells and Structures within Pars Nervosa
- Pituicytes (astroglia cells)
- Herring Bodies (axon bulges containing hormones)
Hormones Released in Pars Nervosa
Supraoptic Nucleus – ADH
- vasoconstriction ↑BP and ↑water permeability
Paraventricular Nucleus – Oxytocin
- contract uterus and ducts of mammary glands
