Anatomy And Hormones Of Pituitary, Hypothalmic Releasing Hormones Flashcards
Neurohypophysis
Posterior lobe Neural lobe Pars nervosa Infundibular stem Median eminence
Adenohypophysis
Anterior lobe Glandular lobe Pars distalis Pars tuberalis Pars intermedia
Embryology of pituitary
Forms as two separate pieces
Ectodermal up growth from roof of mouth->ant lobe
Neuroectodermal down growth->post. Lobe
Small portion of Rathkes pouch may persist as ectopic pituitary tissue
Blood supply
Superior hypophyseal artery-> stalk-> capillaries->portal vessels
Inferior hypophyseal artery->bottom of post pit
Portal vessels-> capillary plexus in ant pit-> inferior hypophyseal veins
Control of hormone release from anterior pituitary
Cell bodies in brain(arcuate nucleus, ventromedial nucleus, preoptic nucleus)-> neurones to ant. Pit->portal veins in to stem->capillary plexus->releasing/inhibitory factors
Control of posterior pituitary
Oxytocin and ADH
Paraventricular nucleus and supra optic nucleus->hypophyseal tract-> capillary plexus
Cells of anterior pituitary
Chromophils-> actively secreting Acidophils 40% Somatotrophs-> GH Mammotrophs->prolactin Basophils 10% Corticoids-> ACTH Thyrotrophs->TSH Cells secreting glycoproteins 10% Gonadotropins->LH, FSH Rest are chromophobes-> reserve
Relations of the pituitary
Optic tract
Cavernous sinus
Compressed by tumours