Hypothalamus III Flashcards
What kind of neurons control the anterior pituitary? Where are they located?
parvocellular neurons located in the arcuate nucleus and the periventricular zone,. Also, axons from paraventricular suprachiasmatic, tuberal and medial preoptic nuclei contribute.
Through what tract do the axons influence the anterior pituitary?
tuberoinfundibular tract. they release factors the median eminence where they go into a primary plexus of fenestrated capillaries. releasing factors are carried by portal veins to a the portal plexus (secondary plexus of fenestrated capillaries in the anterior and intermediate pituitary)
What peptide or transmitter is released to the anterior pituitary based on diffuse regions of the preoptic region?
gonadotropin hormone-releasing hormone
What peptide/transmitter is released to the anterior pituitary based on the periventricular zone in general?
somatostatin
What peptide/transmitter is released to the anterior pituitary based on the the arcuate nucleus?
growth-hormone releasing hormone
What peptide/transmitter is released to the anterior pituitary based on the paraventricular nucleus?
corticotropin-releasing hormone and thryotropin releasing hormone.
Where are thryropropin releasing hormone cell bodies located? From where is it released?
paraventricular nucleus parvocellular cells
released from external zone of the median eminence
What is the action of thyrotropin releasing hormone? How is this system regulated?
stimulate the pituitary to release TSH. TSH stimulates the release of thyroxine (T4) and trilodothyronine (T3). T4 is metabolized to the active form more slowly. Regulated by thryoid hormone receptors on the paraventricular nucleus cells and on TRH producing cells and on the anterior pituitary cells.
What is hashimoto’s throiditis?
increased antibodies to the thyroid peroxidase. this causes inflammation of the thyroid gland, which destroys the thyroid gland- ultimately you get hypothyroid.
how is hypothyroidism classified?
by organ of origin:
primary is caused by problems with the thyroid gland (hashimoto’s thiroiditis)
secondary (pituitary gland- often tumors)
tertiary: hypothalamus
What cells produce growth hormone releasing hormone?
arcuate nucleus.
What cells produce somatostatin?
widespread but mostely periventricular anteriror hypothalamus
How does the growth hormone system work?
growth hoormone releasing factor stimulate the release of growth hormone from the anterior pituitary.
GH stimuates bone growth.
GH also stimulates the liver to make IGF1.
GH and IGF1 both stimulate growth and act to inhibit the release of growth hormone releasing factor. They also promote the release of somatostatin. Somatostatin inhibits the release of growth hormone. Most GH secretion occurs at night.
What happens with GH oversecretion?
In childhood, we see gigantis, after adulthood we see acromegaly
