Endocrine System I & II Flashcards
what are the classifications of hormones?
steroids
small peptides, polypeptides and proteins = peptide hormones
amino acid and arachidonic acid analog and their derivatives = biogenic amines
what are the two ways target organs can be activated (receptor mechanisms)?
cell surface receptors - unable to penetrate the cell membrane
intracellular receptors - hormones that penetrate plasma and nuclear membrane - no second messenger involved
which hormones use cell surface receptors?
peptide hormones
which hormones use intracellular receptors?
steroid hormones
what is the functions of endocrine organs?
regulate activities
maintain homeostasis
coordinate body growth and development
what are the two types of feedback?
positive
negative (more common)
what are characteristics common to all endocrine organs?
reticular fibers
fenestrated capillaries (sinusoids)
secrete hormones
what makes up the diencephalon?
thalamus and hypothalamus
what is the origin of the pituitary gland?
dual: oralectogerm and neuroectoderm
what makes up the anterior pituitary gland?
pars tuberalis
pars distalis
pars intermedia
what makes up the posterior pituitary gland?
median eminence
infundibulum
pars nervosa
whats another name for anterior pituitary?
adenohypophysis
whats another name for posterior pituitary?
neurohypophysis
where does the anterior pituitary come from?
Rathke’s pouch - oralectoderm
where does the posterior pituitary come from?
neuroectoderm
which pituitary has an abundance of cells (stains dense)?
anterior
what pituitary stains lighter and why?
posterior
presence of myelin - nerves etc.
what cells make up the anterior pituitary?
chromophobes
chromophils
-acidophils (35%)
-basophils (15%)
what two types of cells make up acidophils?
somatotropes
mammotrophs/lactotrophs
what does somatotropes secrete?
GH (growth hormone)
what does mammotrophs/lactotrophs secrete?
PRL (prolactin)
what three cell types make up basophils?
gonadotrophs
corticotrophs
thyrotrophs
what does gonadotrophs secrete?
FSH
LH
what does coricortrophs secrete?
ACTH (adrenocorticotropin)
what does thyrotrophs secrete?
TSH
which chromophils act on other endocrine organs?
basophils = tropic
what does FSH and LH target?
testes or ovaries
what does TSH target?
thyroid
what does ACTH target?
adrenal cortex
wht does prolactin target?
mammary glands
what does MSH target?
melanocytes
what does endorphin target?
pain receptors in the brain
what does growth hormone target?
liver
bones
which hormones are tropic?
FSH LH TSH ACTH (basophils)
which hormones are nontropic ?
prolactin
MSH
endorphin
which hormones has both tropic and nontropic effects?
growth hormone
what is the function of chromophobes?
stem cell?
supportive cells?
degranulated cells?
what is the pars intermedia associated with in terms of cells?
cells producing MSH
what lines pars intermedia?
basophilic cuboidal cells
where are hormones produced?
hypothalamus
how are hormones transported and where are hormones stored?
transported along hypothalamo-hypophyseal tract
stored in axonal dilations called “herring bodies”
what are the two parts of the hypothalamus that secrete hormones?
supraoptic nucleus
paraventricular nucleus
what does supraoptic nucleus secrete?
ADH (anti-diuretic hormones/vasopressin)
what does paraventricular nucleus secrete?
oxytocin
what are the two functions of ADH
vasocontriction of arterioles
increase water permeability in collecting tubule
what are the two functions of oxytocin?
contraction of the myometrium during labor
contraction of myoepithelial cells of lactating mammary alveoli
what are the two parts of the adrenal medulla?
cortex
medulla
where is cortex derived from?
intermediate mesoderm
where is medulla derived from?
neural crest
whats in the center of the adrenal medulla?
central v.
what are the three zones of the adrenal cortex?
z. glomerulosa (15%)
z. fasciculata (65%)
z. reticularis (10%)
what does the zona glomerulosa secrete? what regulates it?
aldosterone (minteralocorticoid)
regulated by angiotensin II
what does the zona fasciculata and zona reticularis secrete? what regulates them?
cortisol (glucocorticoid) (more from fasciculata)
androgens (DHEA) (more from reticularis)
regulated by ACTH from pituitary
what are the characteristics of spongiocytes?
exhibit cluster of lipid droplets
fenestrated capillaries close to cells
well developed sER
mitochondria with tubular cristae
where is the spongiocytes located?
zona fasciculata
what cells are found in the adrenal medulla?
chromaffin cells (affinity for chromium salts)
what neurons are found in adrenal medulla?
modified post-ganglionic sympathetic neurons = no axons, no dendrites
how are the neurons in the adrenal medulla stimulated?
preganglionic sympathetic neurons - fight or flight
what does the adrenal medulla secrete?
adrenaline and nor adrenaline (catecholamines)
what is a characteristic of adrenal medulla?
venous sinusoids
what do chromogranins do?
impart brown color to adrenal medullary cells
what are the endocrine cells found in pancreas?
islets of langerhans - tail there is more
what are the cell types found in islets of langerhans?
alpha
beta
delta
F-cells or PP cells
what does alpha cells secrete?
glucagon (20%)
what does beta cells secrete?
insulin (70%)
what does delta cells secret?
gastrin and somatostatin (not the somatostatin that regulates the pituitary GH) (5%)
what are F cells also called?
PP cells - pancreatic polypeptide (5%)
with what tool can you see the individual cells in the islets of langerhans
immunocytochemistry
what hormones stimulates the thyroid?
TSH
what does the thyroid secrete?
T3 and T4
what is a characteristic of thyroid?
fenestrated capillaries
whats the parenchyma of thyroid?
follicle - lined by follicular cells (simple cuboidal)
what cells are found in the stroma of the thyroid and what do those produce?
C cells/parafollicular cells /”clear cells”
calcitonin - lowers blood calcium levels
what regulated metabolic activity of thyroid gland
iodine storage in T3 and T4
what does the parathyroid hormones stimulate?
osteoclast to free calcium from bone
stimualted the calcium uptake from intestines and kidney
what types of cells are found in the parathyroid? what do those cells secrete?
chief cells- PTH - increase blood calcium levels, decrease blood phosphate levels
oxyphil cells - unknown functions
what cells are present in pineal gland?
melatonin secreting pinealocytes - arranged in cords
glial cells - astrocytes
what are characteristics of pineal glands?
calcium deposits - corpora arenacea (brain sand) - extracellular space
what is nerve innervation to pineal gland?
post ganglionic sympathetic fibers derived from superior cervical ganglion
describe metatonin - inhibits, when do we secrete it, potent what, when it is high?
inhibits early puberty
secreted during darkness
postent antioxidant
high when young, reduced when we age
what do the thymopoietins, thymic factor, and thymosins of the thymus gland influence?
development of T lymphocytes
