Histology of the endrocrine system Flashcards
adenohyposis
anterior pituatary
separated into pars distalis
pars intermedia
pars tuberalis
neurohyphosis
posterior pituatary
pars nervousa
infundbiluar stalk
anterior pituatary embroyo
comes from ectoderm (rathke’s pouch)
posterior pituatary embroyo
comes from neuroectoderm
Neurosecrotory cells
from the hypothalmus
regulate the anterior pituatary
Regulation of the posterior pituatary
occurs from the paraventricular nucleus (makes oxytocin) and the supraoptic nucleus (produces ADH)
Primary capillary plexus
surronds the median eminence and infundilum
has fenestrated and sinusodial capillaries
blood supply to pars distalis
secondary capillary plexus
surrounds the pars distalis
blood supply to pars distalis
pars distalis types of cells
acidophils
basophils
chromophobes
Somatotrophs
acidophil
secrete growth hormone
+ GHRH
- somatostatin
act on liver, muscle, bone, kidney
Lactrotrophs
acidophil
secrete prolactin
+ TRH and VIP
- dopamine
act on breasts
corticotrophs
basophil
produces ACTH
+CRH
-cortisol
act on adrenal cortex
gonadotrophs
basophil
produces FSH and LH
+ GnRH
act on gonads
thryotrophs
basophil
secrete TSH
stimulate TRH
inhib by somatostatin
act on thyroid
Pars intermedia
contains colloid-filled cysts
basophils and chromophobes –> makes MSH (stimulates melanin) and B-endorphin
Pars tuberalis
has vessels of portal system
Pituatary adenoma affecting growth hormone
causes gigantism and acromegaly (adults)
Pituatary adenoma affecting lactotrophs
milk production in non-lactating females
infertility
erectile dysfunction
Cushing’s disease
overproduction of ACTH - affecting corticotrophs
Pituicytes
cells in the posterior pituatary
glial cells
posterior pituatary axons
arise from supraoptic and paraventricular nuclei of hypothalmus
Herring bodies
swelling of axons in the posterior pituitary
associated with fenestrated capillaries
contain ADH and oxytocin hormones
ADH
from neurons in supraoptic nucleus
released when low blood volume or high blood osmolarity
promote water reabsorption
Oxytocin
from paraventricular nucleus
released during labor or by contraction of myoepithilial cells in the breast
Adrenal cortex
from intermediate mesoderm
produces steroid hormones
has three layers: zona glomerulosa, fasciculata, reticularis
Adrenal medulla
from neural crest
produces epinephrine and norepinephrine
Adrenal cortex hormones
minarocorticoids
guloccorticoids
androgens
zona glomerulosa
outermost
secrete mineralocorticoids (aldosterone)
small, basophilic cells
stimulated by angiotensin II and weakly ACTH
zona fasiculata
middle layer
large polyhedral cells in cords
secrete glucocorticoids
stimulated by ACTH
zona reticularis
deepest layer
small cells in cords separated with spaces (capillaries)
produce weak androgens (DHEA) and some glucocorticoids
stimulated by ACTH
chromaffin cells
in adrenal medulla
large, pale polyhedral cells
postganglionic symp neurons
secrete epi and norepi
Central adenomedullary vein
prominent white space in medulla
contraction releases hormones into the blood
Thyroid gland
separated into lobules
has folliciles filled with colloid
colloid
storage of inactive thyroid hormones
folicular cells in thyroid gland (princpal/thyrocytes)
line lumen of follicles
has short microvillli
secrete T3 and T4
stimulated by TSH
parafollicular cells (C cells)
large, pale staining
secrete calcitonin in response to elevated blood Ca2+
indented nucleus and secretory vesicles
T3 and T4
thryoid hormone - stored as colloid
t4 more abundant
regulate basal metabolism, heat production, contribute to growth and development
calcitonin
thyroid hormone - produced from parafollicular cells
lower blood ca2+ by promoting Ca deposition in bones
supresses osteoclasts
goiter
enlargement of thyroid gland
can be either hyper or hypo gland
hyperthyrodism (graves disease)
weight loss, sweating, tachy
eyes bulg out
hypothyrodism
weght gain, autoimmune, lack of iodine
Parathyroid gland cells
chief cells and oxyphil cells
principal (chief) cells
secrete PTH - small, more of them
oxyphil cells
larger, eosinophil
no none secretion
PTH function
opposite of calcitonin
secreted in response to low Ca
pineal gland
regulates circadian rhythms
secretes melonin, serotin, norepi, dopamine
has corpora arencea - brain sand
pinealocytes
cells in pineal gland
secrete melanin and serotonin
corpora arencea
brain sand found in pineal gland
