Peptide Hormones Flashcards
describe the composition of peptide hormones
contain amino acids or amino acid derivatives
peptide hormones bind to ____ and work through ____
cell surface receptors
G reactive proteins (intercellular signalling)
thyroxine is a ____ hormone that acts like a ____
peptide
steroid
most hypothalamic-pituitary hormones are ____
peptide hormones
peptide or protein hormones have cell receptors…
on the cell membrane
Describe the effects of ADH on urine and plasma osmolality
opposite effects on urine and plasma osmolality
increases blood volume (^H2O), decreases urine volume (removes H2O)
what causes hypernatremia?
high aldosterone or diet
where is ADH produced?
supraoptic nuclei of hypothalamus
where is ADH released?
travels down the stalk and released by posterior pituitary
location of action of ADH
late distal convoluted tubule and cortical region of collecting duct
mechanism of action of ADH
- ADH inserts aquaporin in membrane of DCT
- allows H2O to be reabsorbed into blood
- H2O dilutes Na in blood -> negative feeback stops release of ADH
what effect does vasopressin have on blood vessels?
constricts blood vessels
what stimulates production of oxytocin?
childbirth or mechanical suckling
where is oxytocin produced?
paraventricular nuclei of hypothalamus
where is oxytocin released
travels down stalk and released from posterior pituitary
actions of oxytocin
- contracts uterus and results in childbirth
- travels to myoepithelial cells of breast causing milk let-down
what neuroendocrine hormone plays a major role in regulation of a nonendocrine target gland?
prolactin
acts on breast
what stimulates production of prolactin?
localized drop in dopamine in hypothalamus following pregnancy & birth
for milk to flow from the nipple to the nursing infant ____ secretion from the posterior pituitary must occur.
oxytocin
where is prolactin secreted from?
anterior pituitary (lactotropes)
what is the action of prolactin?
causes breast to produce milk
Which of the following is both synthesized & stored
in the hypothalamus?
A) ADH
B) Thyroid-stimulating hormone (TSH)
C) LH
D) Somatostatin
E) Somatomedin
somatostatin
release of oxytocin is an example of ____ secretion
neuroendocrine
what pituitary hormone has a chemical structure similar to ADH?
oxytocin
peptides containing 9 AAs
how does ADH differ from oxytocin in structure?
2 amino acids: arginine & phenelalanine
Increased sodium in the blood is a direct action of what hormone?
Aldosterone
Increased production of aquaporin channels is mediated primarily through secretion of what hormone?
Vasopressin (ADH)
