Endocrine System Flashcards
Communicates via chemical messengers (hormones), secretory products of endocrine cells, carried by bloodstream to target tissue containing receptors
Endocrine
_____ organs composed of secretory cells of epithelial origin, characterized by prominent nuclei & numerous organelles; Lack ducts & secrete hormones into surrounding interstitial space; Possess rich blood supply with fenestrated capillary networks to absorb & transport hormones; integrate function of physiologic systems
Endocrine organs
______ coordinates endocrine functions of body—acts as intermediary between autonomic nervous system & end
Hypothalamus
T/F: Most endocrine glands form discreet organs
True
specialized appendage of brain; Lies beneath third ventricle in sella turcica(“Turkish saddle”) of sphenoid bone
Pituitary gland (= hypophysis)
Secretion of pituitary hormones controlled by ______, with complex blood supply
hypothalamus
allows communication with hypothalamus from pituitary gland
hypophyseal portal system
Hypothalamus controls secretion of anterior pituitary via _________ (hormones)—
hypothalamic regulating factors
Releasing factors _____ secretion
stimulate
inhibitory factors ____ secretion
inhibit
_____ hormones have non-endocrine target organ
Direct acting hormones
GH, ADH, MSH, oxytocin, prolactin are ___ hormones
Direct acting hormones
_____ hormones target organ is another endocrine gland
trophic hormones
TSH, ACTH, FSH, LH are ____ hormones
trophic hormones
Thyroid gland, adrenal cortex, & gonads all _________ endocrine glands
pituitary-dependent
_____ portion of pituitary contains glandular epithelial tissue
Anterior portion
____ portion of pituitary contains neural secretory tissue
posterior portion
Specialized glandular tissue, arises from evagination of ectoderm from oral cavity in region of pharynx called Rathke’s pouch
Anterior pituitary: “Master gland” (=adenohypophysis = pars anterior = pars distalis)
Anterior pituitary arises from portion of pharynx called ____ ; oral ectoderm that migrates to brain
Rathke’s pouch
What are the 3 portions of Rathke’s pouch?
pars distalis, pars intermedia, and pars tuberalis
Portion of Rathke’s pouch that is bulk of anterior pituitary
pars distalis
Portion of Rathke’s pouch that is thin layer between anterior & posterior pituitary; Secretes MSH & ACTH; Frequently contains cystic remnants of Rathke’s pouch
pars intermedia
Portion of Rathke’s pouch that is extension of anterior pituitary; forms collar ~pituitary stalk (=infundibulum)
pars tuberalis
_____ (portion of anterior pituitary) secretes bulk of pituitary hormones, including both direct acting & trophic hormones
Pars distalis
Direct acting hormones secreted by pars distalis
GH & prolactin
Trophic hormones secreted by pars distalis
TSH, ACTH, FSH, LH
Secretory cells of anterior pituitary traditionally classified as ____ or _____
chromophils (which stain) or chromophobes (don’t)
Do chromophils stain?
Yes
Do chromophobes stain?
No
What are the 2 types of chromophils?
Acidophils and Basophils
stain with acidic dye; pink on H&E
Acidophils
stain with basic dye; pale blue to light purple on H&E
Basophils
small cells, don’t take up either dye, clear on H&E; represent inactive cells
Chromophobes
What are the 2 types of acidophils?
Somatotrophs and Mammotrophs
What are the 3 types of basophils?
Thyrotrophs, Gonadotrophs, and Corticotrophs
Acidophil: ~50% of cells; sec GH
Somatotrophs
Acidophil: ~20% of cells; secrete prolactin (controls lactation)
Mammotrophs— (= lactotrophs)
Basophil: ~5% of cells; secrete TSH (= thyrotropin)
Thyrotrophs
Basophil: ~5% of cells; secrete FSH & LH
Gonadotrophs
Basophil: ~20% of cells; secrete ACTH, MSH, endorphins
Corticotrophs
Where are the cell bodies of posterior pituitary neurons?
Hypothalamus
Axons of posterior pituitary are surrounded by support cells called
pituicytes
Located ventral to hypothalamus(plus short stalk, infundibulum, which contains axons of neurosecretory origin)•Consists of downgrowth of nervous tissue from floor of diencephalon (third ventricle)
Posterior pituitary
Secretion of posterior pituitary hormones by axons from nerve cells in hypothalamus known as _____(regulated by hypothalamic hypophyseal feedback loop)
neurosecretion
Hypothalamus secretes what 2 hormones via posterior pituitary
ADH(= vasopressin) & oxytocin
Posterior pituitary hormones are Stored in neurosecretory granules in dilations of axons of posterior pituitary known as
Herring bodies
controls blood pressure by altering permeability of renal collecting tubules
ADH
production of ADH => __ urine production (as in diabetes insipidus)
↑ urine production
ADH is Synthesized by neuron cell bodies in _____ of hypothalamus
supraoptic nucleus
promotes smooth Mm contraction in uterus & breast (especially during labor & lactation)
Oxytocin
Oxytocin is Synthesized by neuron cell bodies in _______ of hypothalamus
paraventricular nucleus
Bilateral, lobulated, endocrine gland on anterior/ventral neck; L & R sides connected by narrow isthmus; Surrounded by loose connective tissue capsule with fine connective tissue septa; Embryologically derived from epithelial downgrowth of fetal tongue
Thyroid glands
L & R sides of thymus connected by ____
narrow isthmus
Thyroid gland unique among endocrine glands in storage of large amounts of inactive hormone, an eosinophilic glycoprotein colloid called _____
thyroglobulin
thyroglobulin stored in extracellular _____; structural units of thyroid gland, lined by simple, cuboidal epithelium
follicles
______ cells concentrate iodine 30-40X blood levels, secrete it as thyroglobulin via apical microvilli
Follicular epithelial cells