Posterior Pituitary Hormones Flashcards
(24 cards)
What is the anterior pituitary gland known as?
Adenohyophysis
What’s the posterior pituitary gland known as?
Neurohypophysis
What hormones do the posterior pituitary gland secrete
ADH and Oxytocin
What is antidiuretic hormone also known as?
Arginine vasopressin
What kind of just hormone are ADH and vasopressin?
Peptide hormones that are 9 aa long
What is the segment on ADH that’s cleaved?
Neurophysis 2
What’s the segment on oxytocin that’s cleaved?
Neurophysis 1
What is hypophysectomy?
It’s pituitary removal
What happens after hypophysectomy?
There’s a reduction in posterior protein secretion, but overtime, several ends of the hypothalamic hypophyseal Tract is modified so secretions are returned to normal.
What does adh do?
It increases water retention in the kidneys by increasing permeability of the nephron to water. This decreases urine production. Vasoconstriction of blood vessels also occur.
What happens in the absence of ADH?
The collecting ducts and tubules become almost impermeable to water
What’s the mechanism of action for ADH?
CAMP levels increase when adenylyl cyclase. This increases the number of water channels onto PM. it’s translocated from an intracellular storage site.
What else does ADH do
It’s stimulates arteriolar constriction. It also stimulates renal mesangial cell contraction. It also stimulates acth secretion. It also inhibits renin secretion. It also influences behaviour, learning and memory.
What stimulates ADH secretion?
- When osmotic pressure increases (larger electrolyte concentration)
- Loss of blood – volume receptors located in the atria of the heart detect changes in blood volume and send signals to increase ADH secretion.
What decreases ADH secretion?
Alcohol. Consumption leads to dehydration.
What stimulates thirst?
Increased osmolarity, decreased Blood volume, increased ADH
What is the deficiency in ADH production called?
Diabetes insipidus
What are the side effects in individuals with diabetes insipidus?
Unable to concentrate urine. Large excretion of urine. Dehydration and increased thirst
What causes diabetes insipidus?
Neurogenic - hypothalamic pituitary defect which can be corrected by ADH administration. (Caused by ADH deficiency)
Nephrogenic - there’s normal ADH but there’s a lack of ADH action.
Psychogenic - compulsive water drinkers
What’s enuresis?
Bed wetting
What are the side effects to SIADH
Decreased ECF doesn’t Iead to decreased ADH so there’s increased blood volume and pressure and increased renal glomerular filtration. This leads to a loss of sodium in urine
What’s the treatment for SIADH?
H2O restriction and demeclocycline, which is inhibiting ADH action on kidney
Where is oxytocin degraded?
Liver and kidney
What does oxytocin do on the uterus?
Stimulates contraction of myometrium, plays a role in normal delivery, effects milk let down by contracting myoepithelial cells of mammary gland
