endocrine Flashcards
Pars distalis
main part of the adenohypophysis
Pars nervosa
the main part of the neurohypophysis
Rathke’s Pouch
the evagination from the oral ectoderm that develops into the adenohypophysis
The three anatomical sections of the posterior pituitary
median eminence, infundibulum, and pars nervosa
the three components of the anterior pituitary
pars tuberalis, pars distalis, pars intermedia
3 main functions of the pituitary
regulate growth, reproduction, and metabolism
feedback inhibition
the dual role of hormones as both biologically active molecules and (usually) inhibitors of the initiator molecule
interstitial cells of Leydig
an example of non-endocrine organ endocrine cells found in the testis (another example is islets if pancreas)
which of the 3 families of hormones are quick-acting, but temorary
aa derivative family (tiny) and peptide hormone family
which of the 3 families of hormones are slow-acting
steroids
where do the axons of the neurohypophysis originate
in the hypothalamus (paraventricular and supraoptic nuclei)
hypothalamo-hypophyseal tract
the combined axons of the hypothalamus leading to the neurohypophysis
the temporary storage sites of vasopressin and oxytocin near the axon terminals of the neurohypophysis
Herring Bodies
the only nuclei of the neurohypophysis
pituicytes (25% of the volume)
what is the function of pituicytes
glial-like support cells. processes retract when increased release of vasopressin, oxytocin to the capillary
how is pituitary activity different in diabetes insipidus
decreased vasopressin leading to polydipsia, copious urine production
are the main secretory cells of the anterior pituitary chromophobes or chromophils
chromophils
primary plexus
the superior capillary bed of the adenohypophysis where axons terminate with HYPOTHALAMIC RELEASING HORMONES
the 4 structures of the adenohypophysis vasculature
superior hypophyseal art, primary plexus, long portal veins, secondary plexus
most abundant pars distalis cells
acidophils: SOMATOTROPHS and MAMMOTROPHS
acidophils secrete…
prolactin and somatotropin (GH)
basophil location
periphery of pars distalis
corticotrophs
basophilic cells secreting adrenocorticotropic hormone (ACTH)
thyrotrophs
basophilic cells secreting TSH (stimulates T3, T4 hormone secretion)
gonadotrophs
basophilic cells secreting FSH and(LH) interstitial cell-stimulating hormone
what ARE chromophobes
stem cells or degranulated chromophils
which cells of the pars distalis are identified as neither chromophobes nor as chromophils
fillicullostellate cells (FS) - long processes that make gap junctions with neighboring cells
appearance of pars intermedia
cuboidal cell-lined colloid (Rathke’s) cysts with basophilic cord cells
what hormone is synthesized in the pars intermedia
proopiomelaninocortin, becomes melanin stimulating hormone
cell types of the pars tuberalis
low columnar cord arrangement. basophilic types same as in the Pd.
does the pars tuberalis lie mostly on the anterior or posterior side of the hypophyseal stalk
anterior
T4
thyroxine - metabolism stimulant
T3
triiodothyronine- metabolism stimulant
why is thyroid a unique endocrine gland
is secretory substance is stored extracellularly
the colloid made of both T3 and T4 filling the follicles of the thyroid
thyroglobulin (large glycoprotein)
how is T3 and T4 processed for secretion
colloid is enveloped by the FOLLICULAR CELLS and cleaved to release into capillaries
morphology of follicular/ pricipal cells of thyroid
tallest when active. can range from squamous to low columnar. form pseudopodia to envelop colloid.
location of parafollicular cells
in clusters near the thyoid follicles within the epithelium but not reaching the lumen
function of parafollicular cells
secrete calcitonin (inhibits osteoclasts) when serum levels of calcium are too high
appearance of parafollicular cells
very few in the thyroid, but large. pale staining.
encapsulated ovoid capsules of parenchymal cells posterior to the thyroid
parathyroid glands (4)
PTH and its function
parathyroid hormone- regulates bone, kidney, and intestines to INCREASE calcium levels (opp. of calcitonin)
principle cells of the parathyroid
CHIEF CELLS- secrete PTH
non-secretory cells of the parathyroid
OXYPHIL CELLS - darker-staining, unknown function
order of PTH activity
PTH->osteoblasts->osteoclast-stimulating factor-> increase in number and activity of osteoclasts
adrenal meddula secretes..
norepinephrine and epinephrine
adrenal cortex secretes…
corticosteroids
mineralocorticoids do this
increase fluids and electrolytes (ex: aldosterone)
mineralocorticoids are secreted/ stimulated by…
secreted by the ZONA GLOMERULOSA of adrenal cortex stimulated by ANGIOTENSIN II
this layer of the cortex has abundant sER
ZONA GLOMERULOSA
gluocorticoids do this…
control metabolism (ex: cortisol and corticosterone)
glucoocorticoids are secreted/ stimulated by…
secreted by the ZONA FASCICULATA adrenal cortex stimulated by ACTH
features of the the zona fasciculata
SINUSOIDAL CAPILLARIES, rich in lipids, cells are called SPONGIOCYTES
these hormones are secreted from the zona reticularis
glucocorticoids and androgens
appearance of the zona reticularis
dark-staining degenerating cells with few lipid droplets
the layers of the adrenal gland from top to medulla
glomerulosa, fasciculata, reticularis
the two cell types of the adrenal medulla
chromaffin cells and sympathelic ganglion cells
chatecholamines
norepinephrine and epinephrine secreted by the chromaffin cells
adrenal medulla is innervated by the
hypothalamic spalanchnic nerves
the two arteries arising from the subcapsular plexus of the adrenal gland
short cortical arteries (leading to the adrenocortical sinusoid) and long cortical arteries (unbranched until medulla)
the pineal gland is made of these melatonin-secreting cells
pinealocytes
what other non-secretory cells makes up the pineal gland
interstitial cells (astrocyte-like)
what is the function of melatonin
eliminates free radicals during oxidative stress, induces sleep
brain sand (corpora arenacea)
deposits of concentric calcium phosphate and carbonate rings that increase throughout life, shrinking during active pineal secretion
functional structural unit of the thyroid
follicle
