1) Histo of Pituitary, Hypothalamus and Pineal Flashcards
what are endocrine cells always very close to?
fenestrated capillaries
5 major classes of hormones and examples of each
small neuropeptides: GnRH large proteins: LH, FSH amino acid derivatives: dopamine, epi vitamin derivatives: vitamin D steroids: cortisol, estrogen
negative feedback with thyroid hormones
TRH from hypothalmus causes AP to release TSH and neg inhibit hypothalamus
-Thyroid hormones (T3 and T4) released from thyroid gland inhibit release of TSH from AP and TRH from hypothalamus
location of the hypothalamus
floor of the diencephalon
forms part of the wall of the 3rd ventricle
hypothalamus regulates by:
1) releasing and inhibiting hormones
2) produces own hormones and stores in PP
3) oversees ANS thereby helping stimulate adrenal medulla via sympathetic innervation
what hypothalamic nuclei primarily produces ADH
supraoptic
what hypothalamic nuclei primarily produces oxytocin
paraventricular nuclei
hypothalamus ____ anterior pituitary ____ thryoid ____
hypothalamus: TRH
Anterior pituitary: TSH
thyroid: T3 and T4
hypothalamus ___ anterior pituitary ___ gonads is target tissue
Hypothalamus: GnRH
Anterior pituitary: FSH and LH
FSH stimulates
follicular development (ovaries) spermatogenesis (testis)
LH stimulates
ovulation, estrogen and progesterone production (ovaries) testosterone production (testes)
hypothalamus ____ anterior pituitary ___ adrenal cortex target to release __
hypothalamus: CRH
AP: ACTH
adrenal cortex: cortisol
hypothalamus ____ AP ____ stimulates growth
hypothalamus: GHRH
AP: GH
stimulates growth, decreases glucose uptake, increases protein synthesis, organ size, lean body mass
somatostatin inhibits
GH and TSH from the anterior pituitary
PIH (dopamine) inhibits
release of prolactin from AP
prolactin stimulates ___ and inhibits
stimulates: lactation
inhibits: GnRH, FSH, LH
location of the pituitary gland
in sella turcica within the sphenoid bone of skull
**posterior to the optic chiasm
nonfunctional pituitary adenoma
and symptoms
pituitary tumor >1 cm
- compresses optic chiasm = bitemporal hemianopsia (issues with periphheral vision)
- compresses pituitary = hypopituitarism
- headache
pituitary embryogenesis: oral ectoderm
becomes anterior pituitary (adenohypophysis)
pituitary embryogenesis: neuroectoderm
becomes posterior pituitary (neurohypophysis)
neuroectoderm remains as
evaginates from floor of diencephalon, never detaches from brain, remains as infundibular stalk
anterior pituitary evaginates from roof of mouth and forms ___ residual tissue from here can cause?
rathke’s pouch, residual tissue can cause tumor called craniopharyngioma
craniopharyngioma: location, causes __ often contains __
- benign childhood brain tumor that usually is suprasellar
- can compress optic chiasm and cause bitemporal hemianopsia
- often contains cystic spaces and calcifications
adenohypophysis 3 parts
pars distalis- anterior portion
pars tuberalis- surrounds infundibular stalk
pars intermedia- division betweeen anterior and posterio
neurohypophysis 2 parts
pars nervosa
infundibular stalk
pars distalis made of
glandular epithelial cells arranged in thick cords
fenestrated capillaries
-part of secondary capillary plexus
some CT stroma
6 hormones of pars distalis
FLAT PiG
FSH, LH, ACTH, TSH, Prolactin, GH
2 groups of cells pars distalis
chromophils: acidophils and basophils
chromophobes: stain poorly
chromophobe description
stain poorly, only nuclei visible, no hormone production
basophil hormones produced
FLAT
acidophil hormones produced
Prolactin, GH
FSH is stimulated by __ and inhibited by ___
also feedback inhibition
stimulated: GnRH from hypothalamus
inhibited by inhibin produced from sertoli cells
also feedback inhibited by estrogen in females
effect of FSH
stimulates ovarian follicle maturation and estrogen production in females
stimulates sertoli cells to produce sperm in males (spermatogenesis) inhibin also stimulated
luteinizing hormone stimulated by and inhibited by
stimulated by GnRH from hypothalamus
inhibited by: feedback inhib by estrogen and progesterone in females and testosterone in males
LH effects
triggers ovulation and stimulates ovarian production of estrogen and progesterone in females
-promotes leydig cell production of testosterone in males
Kallman syndrome
delayed/absent puberty and anosmia
-prevents migration of GnRH neurons to arcuate nucleus and olfactory neurons to olfactory bulb
ACTH stimulated by ___ inhibited by __
stimulated by CRH from hypothalamus ina circadian manner
inhibited by glucocorticoids (cortisol) feedback inhibition
increased cortisol reaults in a reduction of CRH secreted from hypothalamus
TSH inhibited by__
thyroid hormones (T3 and T4)
prolactin stimulated by
prolactin releasing hormone and TRH (from hypothalamus)
decreased PIH
enhanced by estrogens, BC, breast feeding, dopamine antagonist drugs
prolactin is inhibited by
PIH (dopamine)
effect of prolactin
stimulates milk production and promotes lactation
inhibits release of GnRH and thus FSH and LH
Growth Hormone stimulated by:
-GHRH
-hypoglycemia, low levels of FAs
high blood levels of aa’s, exercise
Growth hormone inhibited by
somatostain,
feedback inhibition by GH and IGF-1
-hyperglycemia, hyperlipidemia, obesity, emotional deprivation
IGF-1
GH stimulates the liver to make IGF-1 aka somatomedin which then works on target tissues such as bone muscle, fat
pituitary gigantism
due to loss of eedack control of GH secreting tumor in pituitary
acromegaly
excessive adult production of GH
-due to loss of feedback control of GH secretion or to GH secreting tumor in pituitary
dwarfism
caused by insufficient GH
pars intermedia: function and consists of
function unknown
consists of:
-small basophils
colloid filled follicles lined by pale cuboidal cells
pars intermedia in animals such as frogs
synthesize proopiomelanocortin which is a a/B melanocyte stimulating hormone which stimulates melanin production
infundibulum 2 parts
pars tuberalis (surrounds infundibular stalk, part of anterior pituitary) infundibular stalk (neural portion, part of posterior pituitary)
infundibular stalk
-what does it connect and 2 parts
thin neural stalk connecting the median eminence of hypothalamus to the pars nervosa
1) median eminence
2) infundibular process
Pars nervosa: pituicytes
glial like cells support numerous unmyelinated nerve fibers traveling from the hypothalamus
herring bodies
- in pars nervosa
- expanded axon terminal filled with stored ADH and oxytocin
- neurophysin carrier: carrier protein takes ADH or oxytocin and takes down terminal axon to swellings where it is stored before release
what is the release of ADH regulated by
hypothalamic osmoreceptors and baroreceptors
function of oxytocin
contraction of SM
- uterine contractions during labor and after to contract uterus back to normal size
- breast myoepithelial cells facilitate milk ejection
- feel good hormone
pituitary blood supply
internal carotid artery–> superior hypophysial artery–> median eminence and infundibulum
internal carotid artery–> inferior hypophyseal arteries—>pars nervosa
supeior hypohyseal gives rise to __ which does what
-primary capillary plexus in the median eminence which collects hypothalamic releasing and inhibitory hormones
primary capillary plexus drained by ____ and delivers blood into ___
hypophyseal portal veins
secondary capillary plexus (in pars diestalis)
inferior hypophyseal arteries give rise to the ___ which does what
3rd capillary plexus
-supplies and collects hormones from the posterior pituitary and sends them into cirulation via own hypophyseal veins
pineal gland develops from what and where
posterior outpocketing of the roof of diencephallon in midline of 3rd ventricle
main function of pineal gland
to manufacture melatonin and serotonin
how is pineal gland regulated
by postganglionic sympathetic from superior cervical ganglion
pineal gland is made of what
pinealocytes: make melatonin and serotonin
neuroglial cells: support
calcified granular material: increases with age
contains no neurons
pinealocytes are regulated by what receptors
beta-adrenergic receptors
melatonin is syntheiszed from what?
tryptophan
melatonin effects
contributes to drowsiness when lights turned down
-acts to delay sexual development until puberty by inhibting GnRH and GH
pineal tumors linked to __
precocious puberty
-decreaes in melatonin—>sexual maturity early
