how does angiotensin 2 help regulate water and salt intake?
-AngII binds AT1 R in the SFO > increase thirst (SFO> SON/PVN and MPN)
- ang2 binds AT1 R in OVLT> increase salt app
describe ang2 effects on the kidneys
- promote sodium retention (bind AT1 R in kidney> increased act of Na+/H+ exchanger (which is an antiporter that allow Na to enter cell from kidney tub while excreting H+)
- inhibit further release of renin (negative feedbck mec to control release of renin)
describe ang2 effect on the vasculature
- binds AT1 R expressed in vascular SM > couples through Gq > activate IP3 > increase intracel cal > promotes contraction of SM lining blood ves
describe how ang2 effect anterior pit
- increases ACTH release > ACTH binds MC2R in adrenal cortex > stim synthesis and release of glucocorticoids, Mineralocorticoids, and Adrenal androgens
what is aldosterone and what does it release in response to and function
- a mineralocorticoid
Release in response to: Hyponatremia. Hyperkalemia
Maintains blood volume and pressure by:
- Promotes sodium reabsorption from the kidneys
- Increases excretion of potassium
- Increases water reabsorption through osmosis
describe aldosterone binding to R
Receptor name and the result
- binds corticosteroid R (T1 mineralocorticoid R expressed in cytoplasm of cells in late distal tub and collecting duct)
- binding > translocation of complex to nucleus > increase transcription of Na Ch (increase reuptake of Na from lumen to tubule) and Na/K ATPase (increase expression of Na pumps)
how does aldosterone effect the CNS
- stimulate R of the NTS > salt appetite
- also synergizes with Ang2 to increase salt app
how do we know we got enough salt?
- salt satiety mainly sense in periphery
- R in liver help inhibit salt app
- increase BV sensed by baroR inhibit salt app
What are disease states with decreased activity of the aldosterone system and symptoms
- hypoaldosteronism: inability to produce sufficient quantities of aldosterone
- Classical pseudohypoaldosteronism: 1) Mutations in the MR can impair its activity
2) Mutations in amiloride-sensitive Na+ channel
symptoms: Patients exhibit hypotension, hyperkalemia (due to decreased retention of Na+)
What are disease states with increased activity of the aldosterone system and symptoms
- Primary aldosteronism: Increased production of aldosterone
- Pseudoaldosteronism: Mutations in amiloride-sensitive Na+ channel that interfere with its downregulation > Constitutively active
symptoms: Patients exhibit hypertension, hypokalemia (due to excessive retention of Na+ and H2O (by osmosis))
