18.3 Pituitary gland Flashcards
sella turcica
depression in the shpenoid; where pituitary gland lies
pituitary gland hangs inferior to the
hypothalamus
infundibulum
structure that connects the pituitary gland to the hypothalamus
pituitary gland is held in position by
sellar diaphragm
All nine hormones secreted by the pituitary gland use _______ as a second messenger
cAMP
anterior lobe of pituitary is AKA
adenohypophysis
Regions of anterior lobe
- pars distalis
- pars tuberalis
- pars intermedia
pars distalis
largest and most anterior portion of pituitary gland
pars tuberalis
wraps around adjacent portion of infundibulum
pars intermedia
narrow band bordering posterior lobe
fenestrated capillaries
Near what region?
unusually permeable capillaries (near median eminence)
portal vessels
blood vessels that link two capillary networks (in this case, portal veins)
releasing hormone (RH)
stimulates the secretion of one or more hormones at the anterior lobe
inhibiting hormone (IH)
prevents synthesis and secretion of hormones from anterior lobe
hormone secreted by pars intermedia
MSH
TSH
AKA, stimulation, and effects
AKA: thyrotropin
- released in response to TRH (thyrotropin releasing hormone
- triggers release of thyroid hormones
ACTH
AKA, stimulation, and effects
AKA: corticotropin
- released in response to CRH
- stimulates release of steroid hormones by adrenal cortex.. specifically targets cells that produce gluccocorticoids
gonadotropins
hormones and stimulation
hormones that regulate activities of testes and ovaries…. FSH and LH
-production stimulated by GnRH
hypogonadism
abnormally low level of gonadotropin production. People with this condition do not mature sexually, and cannot produce functional sperm or oocytes
FSH
AKA and effects
AKA: follitropin
- stimulates follicle growth in females, and nurse cells (aid in sperm development) in males
- FSH + LH stimulates secretion of estrogen by ovarian cells in females
- release of inhibin from testes and ovaries
most important estrogen
estradiol
LH
AKA and effects
AKA: lutropin
- FEMALES: induces ovulation, promotes secretion of estrogens and progestins (prepare body for possible pregnancy)
- MALES: stimulates production of androgens by the interstitial cells of the testes
most important androgen
testosterone
PRL
AKA, stimulation/inhibition, and effects
AKA: mammotropin
- PRL stimulates PIH (dopamine) release and inhibits secretion of PRF (prolactin releasing factors)
- stimulates: mammary gland development, milk production during pregnancy
- in males: helps regulate androgen production and makes interstitial cells more sensitive to LH
GH
AKA, stimulation/inhibition, and effects
AKA: somatotropin
- regulated by GH-RH and GH-IH
- stimulates cell growth and replication by accelerating protein synthesis
- liver responds by releasing somatomedins (insulin-like growth factors IGF that stimulate tissue growth)
MSH
AKA, stimulation/inhibition, and effects
AKA: melanotropin
- dopamine inhibits release of MSH
- secreted by pars intermedia
- increases production of melanin by melanocytes
- usually no MSH in bloodstream
posterior lobe of pituitary gland is AKA:
neurohypophysis.. contains axons of hypothalamic neurons
neurons of the supraoptic and paraventricular nuclei manufacture…
ADH and OXT respectively.
-hormones move along axons in infundibulum to capillaries in posterior lobe.. “axoplasmic transport”
ADH
AKA, stimulation/inhibition, and effects
AKA: vasopressin (VP)
- released in response to rise in solute concentration in blood, or a fall in blood volume or blood pressure.. detected by osmoreceptors in hypothalamus
- decrease water loss at kidneys.
- alcohol inhibits release
How does ADH in high concentrations effect blood vessels
vasoconstriction: narrowing of peripheral blood vessels.. elevates blood pressure.
OXT
stimulation/inhibition, and effects
- stimulates smooth muscle contractions in uterus, promoting labor and delivery. (most of this hormone is secreted by uterus and fetus)
- after delivery, promotes ejection of milk by stimulating contraction of myoepithelial cells around alveoli. Neuroendocrine reflex: milk let-down reflex
OXT during sex
levels peak at orgasm.
-causes smooth muscle contractions that may be important to ejaculation; contractions of uterus may help transport sperm toward uterine tubes
diabetes insipidus
cause, effects, treatment
posterior pituitary doesn’t release adequate amounts of ADH. results in polyuria (excessive urine production).
-treated with desmopressin
glucocorticoids
cortisol and corticosterone
