Posterior Pituitary Flashcards
all the names for ADH
- arginine vasopressin (AVP)
posterior pituitary is formed by downward growth of axons and neurons from which nuclei
- supraoptic
- paraventricular
precursors for vasopressin and oxytocin
- V: propressophysin (cleaved to form vasopressin and neurophysin)
- O: proopressophysin (cleaved to form oxytocin and neurophysin)
vasopressin and oxytocin are bonded to ______ prior to storage and release
- neurophysin
action of oxytocin
- stimulates contraction of uterine smooth muscle
- stimulates myoepithelial cells of mammary alveoli (milk ejection)
what stimulates release of oxytocin in the vagina and uterus
in the breast
- distention
- suckling of breast (tactile stimulation)
action of ADH/AVP
- holds onto water in DCT and collecting duct via cAMP and PKA
- binds to V2 receptors to bring in AQP2
- excretion of hypertonic urine
how does ADH/AVP regulate ACTH
- increases CRH release which increases ACTH
tonicity of plasma/sodium concentration that stimulates release of ADH
- increased tonicity or plasma concentration
- even a small rise in tonicity will increase ADH a lot!
hemodynamics that stimulates release of ADH
- low pressure
hormones that stimulate release of ADH
horomones that inhibit release of ADH
- beta adrenergic
- AG II
- prostaglandlins
- ANP
- alpha adrenergic
secretion of ADH is regulated by what receptors
- osmoreceptors in the hypothalamus
- volume receptors in the atrium of the heart
- carotid baroreceptors in the neck
what is the most effective regulator of plasma ADH
- osmolality
patients with ADH/AVP deficiency/insufficiency, have what symptoms
- thirst
- polydipsia
- polyuria > 3L
- nocturia
central DI causes
- trauma
- infiltrative disease
- post surgery
nephrogenic DI causes
- genetic - AVPR2 or AQP mutations
- hypercalcemia
- hypokalemia
- drugs
- renal disease
difference in serum sodium and osmolality in central/nephrogenic DI versus primary polydipsia
- high in DI
- normal/low in primary polydipsia
what test do you use to distinguish DI from primary polydipsia
- water deprivation test
what test differentiates nephrogenic DI from central DI
how
- DDAVP
- in central DI, urine osmolality rises after given DDAVP
- in nephrogenic DI, there is no response to DDAVNP because the kidneys are resistant to it
ADH/AVP level in nephrogenic DI
- high
ADH/AVP level in central DI
- low
ADH/AVP level in primary polydipsia
- low
treatments for central DI
how do they work
- DDAVP - analog of vasopressin with longer half life than vasopressin
- synthetic AVP
- chlorpropamide - potentiates effects of endogenous vasopressin. for patients with partial vasopressin deficiency
treatments for nephrogenic DI
how do they work
- HCTZ - decreases Na reabsorption so water and sodium will be excreted more equally
- aimiloride - blocks lithium uptake in kidney (good for patients with lithium induced DI)
