Hypothalamic/Pituitary Flashcards
How are hormones released from hormone secreting cells into circulation?
Hormones are released into the interstitial connective tissue and then pass directly into blood or lymph circulation. endocrine cells, tissues, glands, and organs are called ductless
Cells are usually arranged how in endocrine glands?
into cords and clumps and are surrounded by an extensive capillary network that allows for more efficient transport of hormones
What is the make up of Adenohypophysis? What is it derived from?
glandular epithelium; ectoderm
What is the make up of neurohypophysis? What is it derived from?
neural secretory tissue; neuroectoderm
Epithelial portion of pituitary gland develops from what?
pharyngeal roof and Rathke’s pouch, Pouch detaches and becomes the cellular portion, anterior pituitary
What forms the neural portion/posterior pituitary?
Down growth of brain ; Neurohypophysis remains attached to hypothalamus by a neural stalk, infundibulum
What is the histological appearance of the posterior pituitary lobe?
less cellular, appears to have streaks & is directly attached to the hypothalamus
What is the histological appearance of the anterior pituitary lobe?
glandular, densely packed cells & not directly attached to the hypothalamus
What are the derivatives from Rathke’s pouch?
Pars distalis, pars Intermedia, pars tuberalis
Where is the pars distalis?
comprises the bulk & arises from the thickened anterior wall of the pouch
Where is the pars Intermedia?
thin remnant of the posterior wall of the pouch that abuts the pars distalis
Where is the pars tuberalis?
forms a collar or sheath around the infundibulum and developed from the thickened lateral wall
What is the make up of the pars distalis?
bulk of the anterior pituitary gland (75%) , cords of well-stained endocrine cells interspersed with fenestrated capillaries & supporting reticular connective tissue
What are the three cell types in the pars distalis based on staining?
acidophils, basophils, chromophobes
What are the staining characteristics of acidophils?
large cells that stain deeply eosinophilic & appear red in Mallory stain (40%)
What are the staining characteristics of basophils?
appear blue/purple in Mallory stain (10%)
What are the staining characteristics of chromophobes?
stain weakly with few or no secretory granules; represent a heterogeneous group of cells including stem cells, undifferentiated progenitors & degranulated cells (50%)
What are the types of acidophils?
somatotrophs and lactotropes (mammotropes)
What do somatotrophs secrete? what stimulates them? inhibits them? general effect?
secrete somatotropin (growth hormone), stimulated by GHRH, inhibited by somatostatin, general effect of increasing metabolic rates, induces the liver to produce insulin-like growth factor-a (IGF-1) which stimulate bone and muscle growth
What do lactotropes secrete? what stimulates them? inhibits them? general effect?
secrete prolactin, stimulated by PRH and oxytocin, inhibited by dopamine/PIF, promotes mammary gland development and lactation, the number of mammotrophs increases following birth, and drop after nursing stops.
What are the types of basophils?
gonadotrophs, thyrotrophs, corticotrophs
What do corticotrophs secrete? what stimulates them? inhibits them? general effect?
secrete precursor to adrenocorticotropic hormone (ACTH), stimulated by CRH (corticotropin releasing hormone), inhibited by high plasma cortisol levels, stimulates synthesis and release of hormones from the adrenal cortex
What do thyrotrophs secrete? what stimulates them? inhibits them? general effect?
secrete thyrotropin (thyroid-stimulating hormone), stimulated by TRH, inhibited by thyroxine (T4) and triiodothyronine (T3) in the blood, stimulates synthesis and release of thyroid hormones
What do gonadotrophs secrete? what stimulates them? inhibits them? general effect?
secrete follicle stimulating hormone (FSH) and luteinizing hormone (LH), stimulated by GnRH, inhibited by hormones produced by ovaries and testes, stimulates ovarian follicle growth and estrogen secretion, steroid hormone production in the testes.