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71 Cards in this Set

  • Front
  • Back
most proteins and catecholamines activate what intracellular cascade?
adenylate cyclase/cAMP
What hormones activate the tyrosine kinase system?
insulin and EGF
Which hormones activate the phosphatidylinositol system?
oxytocin, GnRH, angiotensin II
What is an inhibitor second messenger response?
cGMP
Where is the adenohypophysis derived?
from the ectoderm of the oropharynx (Rathkes pouch)
What forms around the infundibulum?
pars tuberalis
What structure is continuous with the median eminence?
infundibulum of posterior pituitary
What is the blood supply to the pars tuberalis?
superior hypophysial arteries which also supplies the median eminence and infundibulum
Where do the superior hypophyseal arteries arise from?
internal carotid arteries and posterior communicating arteries of the circle of willis
The inferior hypophysial arteries primarily supply what? Where do the vessels arise from?
1) pars nervosa of the posterior pituitary
2) solely from the internal carotids
Where might someone have pituitary ischemia if the internal carotids were occluded bilaterally?
only the pars nervosa because the superior hypophysial arteries receive blood from both the internal carotid arteries and the posterior communicating arteries
What are the nerves found in the anterior pituitary?
postsynaptic autonomic fibers that have secretory and vasomotor function
what are tropic hormones?
hormones that regulate endocrine distant endocrine glands
Are GH and PRL tropic hormones?
no
How are the cells arranged in the pars distalis of the anterior pituitary?
cords and nests with interweaving capillaries
What percentage of the anterior pituitary are chromophobes?
50%, acidophils 40%
Somatotropes constitute what percentage of the pars distalis? How are they characterized?
1) 50%
2) medium-sized, oval cells with round central nuclei
How are somatotropes classified based on stain?
acidophils
what is ghrelins effect on GH?
increases release when food is taken in
How do lactotropes stain?
acidophilic when they have vesicles and chromophic when vesicle depleted
What 2 hormones in addition to dopamine effect PRL release?
TRH and VIP stimulate synthesis and secretion
How can corticotropes be identified under the microscope?
medium sized cells with round eccentric nuclei. they have a strong positive reaction with PAS
A small oval cells with eccentric nuclei stain with both acid and basic dyes and a PAS reagent in the anterior pituitary. What cell type is it?
gonadotrope
Large cells with round eccentric nuclei and are basophillic found in the anterior pituitary are?
thyrotropes
A cell is identified in the anterior hypothalamus that is large and polygonal with oval centrally located nucleus. What cell is this?
lactotrope... note that the somatotrope also has a central nucleus but is medium sized and has a prominent nucleoli
What 2 cell types in the anterior pituitary stain with acid dyes like Orange G but are PAS negative?
somatotrope and lactotrope
what does the posterior pituitary consist of?
infundibulum and pars nervosa
is the posterior pituitary an endocrine organ?
no
Are the axons of the posterior pituitary myelinated?
no
Light microscopy reveals intracellular dilations at the distal end of certain cells in the pituitary. What are we looking at?
herrings bodies at the axon terminals in the posterior pituitary.
What is inside Herring bodies?
ADH and oxtocyn
What effect do low levels of ADH have?
contraction of smooth muscle on arterioles raising blood pressure
At high or low doses of ADH does the blood pressure rise?
low
besides hypertonicity and low blood volume what factors can stimulate ADH release?
pain, trauma, emotional stress, nicotine
What cells in addition to neurosecretory cells are found in the posterior pituitary?
fibroblasts, mast cells, glial cells called pituicytes
what is the function of the pituicyte? How are they identified?
1) they support the capillary network like astrocytes
2) they have round or oval nuclei with pigment vesicles in cytoplasm and have GFAP
What cells is glial fibrillary acidic protein found in?
pituicytes and astrocytes
Where are the cell bodies that release GHRH found?
arcuate nucleus
Where are the cell bodies of neurons that release somatostatin found?
periventricular, paraventricular and arcuate nucleus
Where are the cell bodies that release dopamine found?
arcuate nucleus
CRH is released from what nuclei?
arcuate, periventricular, medial paraventricular
GnRH is released from what nuclei?
arcuate, ventromedial, doral and paraventricular nuclei
TRH is released from which nuclei?
ventromedial, dorsal, paraventricular nuclei
Where does the pineal gland develop from?
neuroectoderm of posterior roof of diencephalon
Where is the pineal gland located?
posterior wall of 3rd ventricle
What is the main cell type in the pituitary? How are they characterized?
1) pinealocytes
2) large deeply infolded nucleus with one or more nucleoli and also have lipid droplets
What other cell is dispersed among the pinealocytes?
interstial (glial) cells... similar to astrocytes
When is corpora arenacea seen? what else is it called?
1) begins in childhood and increases with age
2) known as brain sand
What is the function of the pineal gland?
regulates circadian rhythm via information from the retinohypothalamic tract. Melatonin is inhibited in the day by light signals in retina and increased at night
melatonin has a direct effect to inhibit what hormone?
GnRH
What hormones are concentrated in pineal extracts besides melatonin?
serotonin, NE, dopamine, histamine, somatostatin, TRH
Tumors that destroy the pituitary at a young age can cause what?
precocious puberty
when does the thyroid gland begin to develop? How does it develop?
4th week from endodermal thickening of the floor of the primitive pharynx. Thyroglossal duct moves inferiorly to neck and from thyroid.
What is the remnant of the thyroglossal duct?
pyrimdal lobe of thyroid (40% people)
melatonin has a direct effect to inhibit what hormone?
GnRH
What hormones are concentrated in pineal extracts besides melatonin?
serotonin, NE, dopamine, histamine, somatostatin, TRH
Tumors that destroy the pituitary at a young age can cause what?
precocious puberty
when does the thyroid gland begin to develop? How does it develop?
4th week from endodermal thickening of the floor of the primitive pharynx. Thyroglossal duct moves inferiorly to neck and from thyroid.
What is the remnant of the thyroglossal duct?
pyrimdal lobe of thyroid (40% people)
follicular cells are derived from?
endoderm
What happens to the thyroid during the 7th week?
epithelial cells from 4th branchial pouch incorporate into the lateral lobes of the thyroid and form parafollicular cells
what shape are the cells surrounding the follicles?
cuboidal
When stained with H and E how do follicular cells appear?
basophilic
What is located at the apical surface of the follicular cell?
1) colloidal resorption droplets consisting of lysosomes and endocytic vesicles
2) golgi
where are the parafollicular (C) cells located?
in the follicle basal lamina
What do parafollicular cells secrete?
calcitonin
How do C cells appear when stained with H and E?
pale in small clusters or solitary
What clinical disease is associated with absent calcitonin?
none
When does the fetal thyroid gland become functional?
week 14
what congenital condition results with low or absent thyroid hormone?
cretenism
what is the microscopic appearance of the thyroid in graves disease?
transition to columnar epithelium with depleted areas of colloid surrounding the apical surface