pituitary Flashcards
adenohypophysis: explain the principle features of the anterior pituitary, list the adenohypophysial hormones and explain their homeostatic control, explain the synthesis, storage, release and physiological actions of these hormones and how dysregulation may present (56 cards)
where is the pituitary gland located
just below the hypothalamus within the brain
what are the two distinct pituitary lobes
anterior and posterior
what is the anterior lobe also called
adenohypophysis
adenohypophysis lobe: origin
upgrowth from mouth
principle features of anterior pituitary
hypothalamic factors secreted within median eminence; endocrine action as diffuse into blood vessels through portal vessels and into endocrine cells for hormone secretion; secretory so requires bloodstream circulation
what does the pituitary gland lie in
sella turcica bone
where do hypothalamic neurone axons feed into the anterior pituitary
median eminence
significance of region of median eminence
devoid of blood-brain barrier so rich in capillaries to allow release of hormones
sections of adenohypophysis lobe
pars tuberalis, pars distalis
what is the purpose of the pars tuberalis
wraps pituitary stalk which connects hypothalamus, posterior lobe with pars distalis
what is the purpose of the pars distalis
where most hormone production occurs
which section of the brain dictates actions of anterior pituitary
hypothalamus
where is the primary fenestrated capillary plexus
median eminence
what connects the primary and secondary fenestrated capillary plexus
long portal veins
where does blood arrive into the pituitary gland
superior hypophysial artery
what is a portal network
where blood from the systemic circulation drains from one capillary network to another before returning to the heart
where does blood flow from the secondary fenestrated capillary plexus
into the venous system via the cavernous sinus
fenestrated definition and importance
“leaky”, so allows hormones to leak out and cause an effect
define hypothalamic neurone
neurones from hypothalamus to median eminence which secrete neurosecretions
where are hypothalamic neurosecretions released into
hypothalamo-hypophysical portal system
what do the hypothalamic neurosecretions do when they pass out of the secondary capilary plexus
inform secretory cells to exocytose stored hormones into systemic circulation
hypothalamo-adenohypophysial axis
hypothalamic nuclei → neurones to median eminence → neurosecretions released by hypothalamic neurone into adenohypophysis → adenohypophysial hormones → target organs
effect of hypothalamic hormones on adenohypophysial hormones and purpose
regulate (releasing or inhibitory) to maintain homeostasis
example of adenohypophysial hormone target organ
thyroid
