[HISTO] HORMONE SECRETING CELLS & PITUITARY 1 Flashcards
Endocrine glands are formed of
secretory cells
CT stroma
fenestrated capillaries
steroid hormone secreting cells are characterized by
sER
mitochondria with tubular cristae
lipid droplets
steroid hormones produce
precursor hormones which form steroids by cholesterol metabolism in mitochondria/sER
hormones which can easily diffuse through cell membrane
steroid hormones (lipophilic)
hormones which require cell surface receptor & 2nd messenger to mediate their effect
peptide hormones (hydrophilic)
peptide hormone secreting cells are characterized by
rER
Golgi complex
secretory granules
how do peptide hormones achieve their effect
by binding to membrane receptors—>hormone-receptor complex—> (+) 2nd messenger—>2nd messenger mediates effect
amino acid hormones examples
thyroid hormones
catecholamines
dopamine
ALL DERIVED FROM TYROSINE
pure endocrine glands (5)
1-pituitary
2-pineal
3-thyroid
4- parathyroids
5-adrenal
mixed endocrine glands (6)
1-islets of Langerhans
2-interstitial cells of Leydig
3- Hepatocytes
4-ovarian follicles
5-corpus luteum
6-Hypothalamic neurosecretory cells
scattered isolated cells (5)
1-enteroendocrine cells
2-juxtaglomerular cells
3- cardiac muscle fibers
4- white adipocytes
5- epithelial reticular cells (thymus)
function of enteroendocrine cells
secrete ghrelin in stomach mucosa
(+) appetite & GH release
function of juxtaglomerular cells
*secrete renin
control GFR & BP
*secrete erythropoietin
(+) erythrocyte production in red marrow
(-) erythrocyte precursors apoptosis
function of cardiac muscle fibers
secrete ANF
promotes Na-H2O loss in urine
(DIURETIC EFFECT)
renin’s effect
(+)aldosterone production
↑ Na-H2O retention
∴ ↑ BP
renin release increases in case of
low BP
function of white adipocytes
secrete leptin (satiety factor)
regulates appetite + adipocytes formation
function of epithelial cells of thymus
differentiation & maturation of T-thymocytes
modes of hormone secretion
paracrine
juxtacrine
autocrine
juxtacrine secretion
signaling molecules remain on cell’s surface & mediates respone when target cells make contact
paracrine secretion?
examples?
act on target cells a short distance away
ex: gastrin, histamine
autocrine secretion?
examples?
acts on itself
ex: prostaglandins
gastric hormone is secreted by?
mode of secretion?
pyloric G cells
paracrine
principle organizers of endocrine glands
hypothalamus & pituitary
pituitary is regulated by
(+): hypothalamic secretions
(-): negative feedback
pituitary gland lies outside the___
blood-brain barrier
hypothalamus is regulated by
negative feedback from pituitary & target organ hormones
pituitary grows in size during
pregnancy
site of pituitary
sella turcica
pituitary is physically connected to hypothalamus by
infundibular stalk