Urine Concentration and Dilution Flashcards
Average urine produced per day
1.5L
When is angiotensin released?
Low salt, low water
Effect of angiotensin release
Constrict efferent arteriole preferentially
Increased glomerulus pressure, GFR
What do ACE inhibitors do?
Inhibit constriction of efferent arteriole
Location of osmoreceptor cells
Anterior hypothalamus
Does water come from metabolism?
Yes
From aerobic respiration
Effect of negative water balance on osmolarity
ECF osmolarity will increase
In what is a negative water balance most quickly detected?
ECF osmolarity, not plasma volume
Negative water balance spread through all tissues in the body, and there is more water in ECF than in blood
Effect of vasopressin
Promotes aquaporin recruitment into kidney tubule walls
What do aldosterone and angiotensin II affect?
Na balance
NOT water balance (at least not directly)
Hormones that result in more concentrated urine
Aldosterone
Angiotensin II
Vasopressin
Most important hormone for water retention
Vasopressin
Can make concentrated urine without aldosterone and angiotensin II, but not without vasopressin
Why can concentrated urine be made without aldosterone and angiotensin II but not without vasopressin?
Vasopressin makes the collecting duct permeable to water with aquaporins
Aldosterone increases Na reabsorption in collecting duct –> if duct is impermeable to water, osmotic gradient has no effect
Angiotensin II promotes Na reabsorption in proximal convoluted tubule. Water is reabsorbed here, but not in the collecting duct.
What increases osmolarity?
Loss of water from the body
Normal setpoint for body osmolarity
300mM
