Endocrine Glands Part 1 Flashcards
endocrine system communicates via
chemical messengers (hormones)
chemical messengers (hormones) are secretory products of
endocrine cells
hormones are carried by — to target tissue containing receptors
bloodstream
Endocrine organs composed of secretory cells of --- origin, characterized by (2)
epithelial
prominent nuclei & numerous organelles
Endocrine system lacks
ducts
Endocrine system secretes hormones into surrounding
interstitial space
endocrine system possess rich blood supply with fenestrated capillary networks to (2)
absorb & transport hormones
• Endocrine organs integrate function of — systems
physiologic
— coordinates endocrine functions of body—acts as
intermediary between autonomic nervous system & endocrine system
Hypothalamus
Most endocrine glands form
discreet organs
in pancreas, (2) tissue intermixed
endocrine & exocrine
Pituitary Gland =
hypophysis
pituitary gland ~– diameter, specialized appendage of —
1cm
brain
Pituitary Gland lies beneath
third ventricle in sella turcica (“Turkish saddle”) of sphenoid bone
Secretion of pituitary hormones controlled by —, with complex blood supply
hypothalamus
Pituitary Gland includes
hypophyseal portal system
hypophyseal portal system allows communication with
hypothalamus
Hypothalamus controls secretion of anterior pituitary via
hypothalamic regulating factors (hormones)
- – factors stimulate secretion;
- – factors inhibit secretion
Releasing
inhibitory
Direct acting hormones—
have non-endocrine target organ
e.g., GH, ADH, MSH, oxytocin, prolactin
trophic hormones—
target organ is another endocrine gland
e.g., TSH, ACTH, FSH, LH
(3) all pituitary dependent endocrine glands
Thyroid gland, adrenal cortex, & gonads
Functionally, anatomically, & embryologically, pituitary divided into
anterior & posterior portions
Anterior portion contains — &
posterior contains —
glandular epithelial tissue
neural secretory tissue
“master gland”
anterior pituitary
master gland=
adenohypophysis = pars anterior = pars distalis
anterior pituitary is specialized glandular tissue, arises from evagination of ectoderm from oral cavity in region of pharynx called
Rathke’s pouch
Rathke’s pouch differentiates into 3 distinct
regions of anterior pituitary:
pars distalis
pars intermedia
pars tuberalis
pars distalis—
bulk of anterior pituitary
pars intermedia—
thin layer between anterior & posterior pituitary
pars intermedia secretes (2)
MSH
ACTH
pars intermedia frequently contains
cystic remnants of Rathke’s pouch
pars tuberalis—
extension of anterior pituitary
pars tuberalis forms
collar ~pituitary stalk (=infundibulum)
Pars distalis secretes bulk of pituitary hormones, including both (2)
direct acting & trophic hormones
Direct acting hormones—(2)
GH & prolactin
Trophic hormones—(4)
TSH, ACTH, FSH, LH