Endocrinology: Hypothalamus/Pituitary Flashcards
- Hypothalamus - ____
- anterior pituitary = ________
- posterior pituitary = ________
- ____ blood supply
CNS
adenohypophysis
neurohypophysis
dual
____ and _____ contain neurons that produce vasopressin and OT
supraoptic nucleus and paraventricular nucleus
OT acts on ____ and ____. stimulating what?
uterus(stimulates uterine contractions) and mammary glands (stimulates milk ejection during breast feeding)
vasopressin acts on ____ and ____, stimulating what?
- nephrons in kidneys (increases permeability of distal and collecting tubules to H20)
- arterioles throughout the body (causes vasoconstriction)
Neurohumoral reflex arcs:
vasopressin: _____ and ____
OT: ____ and ____
- ECF osmolality and blood pressure/volume
- cervical stretch and suckling nipple
principle stimuli for the release of ADH: ___ and ____
- increased osmolarity acts on hypothalamic osmoreceptors (dominant factor)
- decreased arterial blood pressure detected by left atrial volume receptors (important only in large changes).
_____ effects on ADH secretion have a larger threshold for secretion, but once secreted have much quicker effects (because higher rate of ADH secretion)
volume effects (compared to osmolarity effects on ADH secretion)
describe the reflex pathway of suckling and OT release.
suckling stimulates mechanoreceptors in nipple, which stimulates the hypothalamus, which stimulates OT release from the posterior pituitary, OT into blood, stimulates contraction of myoepithelial cells surrounding alveoli, leading to milk ejection.
both ____ and ___ are positive feedback loops
OT release in suckling reflex and OT release in cervix stretching during pregnancy.
___ receptor very similar to OT receptor. Thus side-effect of pitocin could be ______
V1
hypertension
ADH - kidney acts through ___ receptor. ___ is second messenger
V2
cAMP
ADH - vascular acts through ____ receptor. ___ is second messenger.
V1
Calcium
oxytocin - smooth muscle acts through _____ receptor, ___ is second messenger.
OR
Calcium
_____ is most abundant hormone released by anterior pituitary
GH
TSH acts on ____, to release _____, causing ____
thyroid gland
T3 and T4
increased metabolic rate
ACTH acts on ____, to release _____, causing ____
adrenal cortex
cortisol
metabolic actions, stress response
Prolactin acts on _____, causing ____
mammary glands
breast growth and milk production/secretion
What are the two actions/pathways of GH?
1) GH acts on the liver to release IGF-1, leading to growth of bones and soft tissues
2) GH can be excitatory or inhibitory on adipose tissue, muscle, and/or liver; leading to metabolic actions
what would be some symptoms of a GH-secreting tumor?
hyperglycemia and increased lipolysis (diabetic-like effects)
FSH in females: ______
FSH in males: ________
females: regulates gamete production. Stimulates growth and development of ovarian follicles, within which the ova, or eggs, develop (also promotes secretion of estrogen by ovaries).
males: regulates gamete production, FSH required for sperm production
LH in females: _____
regulates ovarian secretion of the female sex hormones, estrogen and progesterone. LH also responsible for ovulation and luteinization.
LH in males: ____
LH stimulates the testes to secrete the male sex hormone, testosterone.
name the tropic hormones of the AP
GH, TSH, ACTH, FSH and LH
name the direct acting hormones of the AP
PRL
____, ____, ___, and ____ all act on their target organs by binding with GPCRs that activate cAMP second messenger pathways.
TSH, ACTH, FSH and LH
____ and ____ act through the JAK/STAT pathway
GH and PRL
____ is synthesized as part of a large precursor molecule known as pro-opiomelanocortin (POMC)
ACTH
glycoprotein hormones of the AP
LH, FSH, and TSH
somatomammotrophic hormones of the AP
GH and PRL
what is name of the unique blood supple system of the adenohypophysis? describe it.
hypothalamic-hypophyseal portal system
- nearly all blood supply that reaches AP, must first pass through hypothalamus
- allows for direct transfer of hypophysiotropic releasing and inhibiting hormones to AP in high concentrations, without going into system circ.
1) hypophysiotropic hormones produced by neurosecretory neurons in HYPO enter the HYPO capillaries.
2) hypo capillaries rejoin to form the hypothalamic-hypophyseal portal system, which then branches into AP capillaries
3) the hypophysiotropic hormones leave the blood across the AP capillaries.
4) AP secretes appropriate hormone into these capillaries.
5) AP capillaries rejoin to form a vein going into system circ.
7 CNS hypophysiotropic hormones
TRH CRH GnRH GHRH GHIH PRH PIH (dopamine)
TRH stimulates ____
release of TSH and PRL
CRH stimulates ___
release of ACTH
GnRH stimulates _____
release of FSH and LH
GHRH simulates _____
release of GH
somatostatin (GHIH) inhibits _____
release of GH and TSH**
PRH stimulates ____
release of PRL
Dopamine inhibits _____
release of PRL
how could you differentiate between secondary or tertiary cause of hyperthyroidism?
if lactation present, then tertiary. TRH from hypothalamus stimulates release of TSH and PRL*****
Name some mechanisms that lead to control of releasing hormone secretion.
- basal neurosecretory activity
- neural inputs to neurosecretory nuclei
- neural reflexes and rhythms
- integration of internal/external stimuli
give an example of long-looped feedback
cortisol feeding back on pituitary and hypothalamus
give an example of short-looped feedback
ACTH feeding back on hypothalamus
give an example of ultra-short looped feedback
CRH feeding back on hypothalamus
what is the importance of negative feedback?
- dampens extremes
- maintains “final” hormone constant
- nervous-endocrine reciprocity
- prevent unintentional silliness
of the tropic hormones from AP, which ones exert effects on non endocrine target cells in addition to stimulating secretion of other hormones?
FSH, LH, and GH
