endocrine histo Flashcards
water soluble vs fat hormones?
water - second messenger - eg growth hormone, FSH
lipid - enter cell - eg testosterone, estrogen
water soluble
cell needs receptor - hormone binds, 2nd messenger creates effect
lipid -
enters cell - creates change via nucleas
6 endocrine organs
pituitary adrenals endocrine pancreas thyroid parathyoids pineal
endocrine tissues - 3 tissue types
A - gland is separate entity - eg thyroid
B - scattered mass within exocrine gland - eg leydig in testis, langerhands
c - isolated in another system - eg gastrin cells in pyloris
pituitary
spennoid, turkish saddle - two distinct embyological tissues
adenohypophysis GLAND anterior
neurohypophysis (posterior) NEURAL
anterior - adenohypophysis
3 parts - pars distalis (anterior lobe) main part
pars tuberalis envelopes stem - together making pituitary stalk
pars intermedia - separating anterior, posterior
neurohypophyis - 2 parts
pars nervosa
infundibulum (funnel shape in neck))
two parts - infundibular process and median eminence (funnel)
embryology
anterior comes from below - they meet and bind - anterior form most of the neck
anterior - pouch of Rathke - ECTODERM ORAL cavity
posterior - neurohypophysis - downgrowth from diencephalon - connecting stem reamins as core of infundibular stem or stalk
blood supply - superior hypophysial artery
- from internal carotid - forms first sinusoidal capillary plexus (primary cap plexus) - receives secreteion of neuroendocrine cells of hypothalamus
- caps from primary cap plexus project down - into infundibulum
and pars tuberalis to form portal veins
caps from portal veins form secondary capillary plexus - supplying anterior hypophysis - and received secretions from endocrine cells of anterior hypophysis
is there a direct arterial blood supply to anterior?hypo?
no
portal system allows?
- trasnport of hormones (releasing and inhibiting) from primary cap to hormone producing cells of anterior hyp
- secretions of hormones from anterio hypo into secondary cap plexus and general circulation
- functional integrations of hypo with anterior hypo -
3rd cap plexus?
inferior hypo artery - branch of cavernous carotid art.
from inferior hypophysial arter - supplies nuerohypophysis - collects secretions from neuroendocrine cells - vASO PRESSIN and OXYTOCIN are transported along axons into neruohypo
are superior and inferior arteries connected?
yes, via trabecular artery - this bypasse portal system
pars distalis vs pars nervosa
nervosa is the nervous part - posterior - vasopressin - ANTI dieuretic and oxytocin vs ANTERIOR distalis
pars distalis (anterior) - 3 components
cords of epith cells
CT stronma
fenestrated caps (or sinusoids) which are part of secondary cap plexus
is there a blood-brain barrier in anterio hypo?
no
epith cells are in cords around fenestrated caps carrying blood from hypothalamus. Secretory hormones difffuse into network of capillaries - which drin into hypo veins and from there into venous sinuses
anterior hype - 3 types of cells
acidophils (pink) sides of gland
baso - darker - middle
chromophobes - cells lack staining - have depleted their hormone content losing staining affinity
acidophils secrete 2 things?
growth hormone and prolactin
GROWTH HORMONE (long bones via somatomedins in liver) aka somatotropes - and PROLACTIN (milk secretion, mammary size aka lactotropes or mammotropes
basophiles - B FLAT
FSH, LH, ACTH, TSH
B Flat
FSH, LH
ACTH - corticotropes - secretion of adrenal cortex hormones
TSH - Thyroid - thyrotopin - stim thyroid hormone synthesis - storage and liberation - T3, T4
feedback mechanism between pars distalis and thyroid
pars distalies TSH
thyroid creates T3, and T4 - goes to target tissues AND can give negative feedback to pars distalis and/or hypthalamus
what does hypothalamus send to pars distalis to stim TSH in pars?
TRH