Hypothalamus and Pituitary Flashcards
Where is rathke’s pouch located?
the anterior pituitary
What are the three parts of the anterior lobe of the pituitary?
pars distalis, pars tuberalis, pars intermedia
What are the parts of the posterior lobe of the pituitary
pars nervosa, infundibulum, infundibular stalk, and median eminence
Where is CRH synthesized and what is its main function
Corticotropin releasing hormone is synthesized in the hypothalamus and stimulates cortictropes in the pituitary to secrete ACTH
Where is TRH synthesized and what are the 3 main effects
thyrotropin releasing hormone is synthesized in the hypothalamus and its functions are:
-stimulate thyrotropes in anterior pituitary to secrete TSH
-stimulates lactotropes in anterior pituitary to secrete prolactin
-stimulates melanotropes in pars intermedia to secrete POMC, which is processed into ACTH
Where is GHRH synthesized and what is its function
Growth hormone releasing hormone is synthesized in the hypothalamus and stimulates somatotropes in anterior pituitary to secrete GH
What is the function of somatostatin in the pituitary
it is released by hypothalamic neurons into the anterior pituitary and inhibits somatotrope secretion of growth hormone
Where is GnRH synthesized and what is its function
gonadotropin releasing hormone is synthesized in the hypothalamus and stimulates gonadotropes in the anterior pituitary to secrete FSH and LH
What is the function of dopamine in the anterior pituitary
dopamine is released by hypothalamic neurons and inhibits lactotropes in the pars distalis and melanotropes in the pars intermedia
The hypothalamo-hypophyseal portal system goes to which part of the pituitary
the pars distalis not the intermedia
What are the three main regulatory mechanisms of the anterior pituitary
-hypothalamic trophic hormones
-negative feedback
-paracrine secretions by cells in pituitary
How would you distinguish the pars distalis from the pars intermedia histologically?
The pars intermedia DOES NOT have acidophils
The basophils of the pars distalis include which secretory cells? what products do they produce
-corticotropes: ACTH
-thyrotropes: TSH
-gonadotropes: LH, FSH
The basophils of the pars intermdiea include which secretory cell(s)? what products do they produce?
-melanotropes: ACTH and MSH
The acidiphis of the pars distalis include which secretory cells? what products do they produce?
-Somatotropes: GH
-Lactotropes: prolactin
The acidiphils of the pars intermedia include which secretory cells? what products do they produce
trick question, the pars intermedia DOES NOT have acidophils
Define trophic hormones
hormones that regulate other endocrine glands
Which type of pars distalis cell secrete tropic hormones?
the basophils
True/False: acidophls produce hormones that act directly on target organs
true
True/False: POMC is produced by both corticotrophs and melatontrophs
true
What is the main difference between canine cushings and equine PPID
canine cushings, if the tumor is in the pituitary, will have the tumor in the pars distalis while equine PPID is caused by a tumor in the pars intermedia
True/False: oxytocin and ADH are produced in the pars nervosa
false they are produced by the hypothalamus
What are herring bodies?
dilated portion of hypothalamic axons that act as a neurosecretory vesicle storage site where the hormones are bound to neurophysin
You see a nucleus in the pars nervosa, what cell does it belong to?
pituicyte (aka glial cell/astrocyte of the pituitary)
or endothelial cell
What are the two main regulatory points of ADH?
extracellular fluid volume and osmolarity
Briefly explain how ADH works
increases the number of aquaporins in the apical membrane of epithelial cells in the distal tubule and collecting ducts of the kidney
What are the two main effects of oxytocin
contraction of uterine smooth muscle and mammary gland myoepithelial cells
What are the 6 anterior pituitary hormones?
FSH, LH, ACTH, TSH, GH, Prolactin
True/False: all anterior pituitary hormones are tropic except for prolactin
true
True/False: only the ACTH product of POMC is biologically active
false,
What important pituitary hormone has a circadian pattern of secretion
ACTH
True/False: hormones from the anterior pituitary do not inhibit their own secretion
false
What is the role of IGF-1 in growth hormone secretion? where is it secreted from
IGF-1 is secreted by the liver and stimulates the release of somatostatin which inhibits the secretion of growth hormone by the pituitary
decreased glucose concentration, fatty acid concentration, exercise, stress, fasting/starvation all ____ growth hormone secretion
stimulate
somatostatin, growth hormone, and pregnancy all ___ growth hormone secretion
inhibit
What are some of the major effects of growth hormone
-stimulates the production of IGF-1, stimulates protein synthesis, stimulates lipolysis, inhibits tissue uptake and utilization of glucose
