Endocrine-1 Flashcards
location of receptors will differ
t
steroid hormone receptors are
intracellular
hydrophilic hormone receptors are
extracellular (water soluble)
steroid hormones exert their effects by
changes in gene transcription
synergistic effects
2 or more hormones work together to evoke an action
with synergistic effects together the effect is larger
t
permissive effects
1 hormone enhances responsiveness of target organ to increase activity of a 2nd hormone
exposure of the uterus to estrogen upregulates progesterone receptors is an example of
permissive effects
antagonistic effects
actions of 1 antagonizes effect of another
insulin lowers blood sugar & glucagon raises blood sugar is an example of
antagonistic effects
most hormones have long half-lives
f; short
Thyroid hormone half-life lasts
days
effects of hormones are
dose dependent
large receptors may lose
receptor specificity
what happens when given hormones in pharmacological doses
side effects bc hormone begins binding other receptors & causing other actions; may result in production of derivatives; desensitization & receptor down regulation
receptor down regulation same mechanism as
drug tolerance
receptor down regulation doesn’t occur in your body b/c
we secrete hormones in pulses
sits in sella turcica of sphenoid bone
pituitary
pituitary aka
hypophysis
pars intermedia sits in
between anterior & posterior pituitary
pars intermedia is
fetal structure -> regresses in adults
derivatives of pars intermedia found in
adenohypophysis
acth produces
msh
msh causes
skin darkening
the posterior pituitary produces 2 hormones
f; stores 2
hormones synthesized by anterior pituitary
gh, tsh, acth, fsh, lh, prl
specify what gh does
cellular uptake of amino acids + lipid & protein metabolism
lipid & protein metabolism promotes
tissue growth, mitosis, cell differentiation, muscle synthesis & fat breakdown
gh results in release of
igf (growth factor)
igf has longer half life
t
longer half life aka
longer lasting effects
gh hyposecretion in childhood =
dwarfism
gh hypersecretion in childhood =
gigantism
gh hyposecretion in adulthood =
pituitary cachexia (simmond’s disease): premature aging due to tissue atrophy which involves loss of pituitary function
gh hypersecretion in adulthood =
acromegaly: soft tissue & bone thickening
tsh stimulates
THYR GLAND GROWTH & thyr hormone production (t3+t4)
acth stimulates
release of adrenocortical hormones from adrenal CORTEX
acth hormones
cortisol, aldosterone & weak androgens
fsh stimulates
growth of ovarian follicles & sperm production (gonadotropin)
lh stimulates (females)
ovulation & corpus luteum formation
lh stimulates (males)
testosterone production (gonadotropin)
prl stimulates
milk production & sensitivity of testes to LH
indirectly increases testosterone production
prl
causes water retention by distal nephron regions
adh
oxytocin causes
uterine contraction, mammary gland contractions, & rises during sex
what causes the release of hormones stored in post pituitary
neuroendocrine reflexes/nerve impulses in hypothalamus
corpus luteum
temporary endocrine structure that results in production of estrogen & progesterone; maintains endometrial lining in case egg should get fertilized
how are the ant pituitary & hypothalamus connected
via portal system (communicate via blood)
anterior pituitary hormones regulated by
hypothalamic releasing & inhibiting hormones
there are neural connections between the ant pituitary & hypothalamus
f; no neural connections
portal system
2 capillary beds connected downstream from one another
describe the portal system
cap beds surrounding hypothalamus
cap beds surrounding ant pit
venules connect them
mechanism of anterior pituitary hormones
hormones from hypothalamus travel thru portal system -> bind to pit gl -> stimulate pit gl to release its hormones
