Regulation of Sodium and Water Excretion I/II Flashcards
Formula for extracellular fluid volume:
ECF volume= (2xECF Na content)/ECF osmolarity
What are the four feedback mechanisms?
- ) Renin-angiotensin-aldosterone pathway
- ) Sympathetic nerve activity pathway
- ) Arginine vasopressin pathway
- ) Atrial natriuretic peptide pathway
What is the main reason for the four feedback mechanisms?
Control of an effective circulation volume
Where is renin released?
Lumen of the afferent arterioles
Two mechanisms of renin secretion?
Renal sympathetic nerves (beta 1)
Low afferent arteriole pressure
What does Angiotensin II cause in the kidney?
Inhibit renin production
Sodium retention
What does angiotensin cause the secretion of?
Aldosterone
What does aldosterone cause?
Increase in genetic expression of apical membrane Na+ channels and basolateral Na/K ATPase
What are the critical events that the sympathetic nervous system has on the kidney?
Renin-angiotensin-aldosterone cascade
What are two mechanisms AVP is released?
- ) Low pressure triggers baroreceptors in the atria send signals to the hypothalamus
- ) Osmoreceptors in the hypothalamus monitoring circulating blood (increase in osmolarity causes a increase in water resorption)
What is the normal blood osmolality?
300 mOsm
What does ANP do?
Dilates afferent arterioles
Inhibits renin release
Inhibits A2 actions
Inhibits medullary collecting duct of Na+ resorption
What is the main stimulus for release of ANP?
Distension of the atrial walls
What is pressure natriuresis and diuresis?
Increased pressure in renal artery causes and increase in Na+ excretion causing water to follow and diuresis
Formula for urine water excretion?
Urine water excretion= urine solute secretion/urine osmolality
