Renal V: Water Balance & Micturition Flashcards
By the end of the DCT what percent of solutes and water have been reabsorbed and returned to the bloodstream?
90-95%
How does Na+ enter principal cells in the late DCT and CD?
through leakage channels
What effect does aldosterone on principal cells and how?
increases Na+ & water reabsorption and K+ secretion
How: stimulates synthesis of new pumps and channels
What effect does ADH have on principal cells?
Increases water permeability of principal cells in CD by triggering insertion of aquaporin channels int apical membrane
How do intercalated cells help regulate pH of body fluids?
Secretion of H+ and absorption of HCO3-
How do intercalated cells secrete H+ into tubular fluid?
proton pumps (ATPases): pH drops
How do intercalated cells absorb HCO3-?
via Cl-/HCO3- antiporters: exchange choloride in intersitital fluid for bicarbonate in intercalated cels, HCO3- enters blood and pH rises
What do intercalated cells do when blood pH is low?
- form more carbonic acid from CO2 & H2O
- secrete more H+ into tubular fluid
- exchange more Cl- for HCO3-
more HCO3- enters blood raising pH
What do intercalated cells do when blood pH is high?
(a different group of intercalated cells)
1. form more carbonic acid from CO2 and H2O
2. pump H+ into ISF (pumps in basolateral membrane)
3. exchange HCO3- for Cl- in tubular fluid (exchangers in apical membrane)
What are the effects of diuretics?
slow renal reabsorption of water and cause diuresis (increased urine flow rate)
diuresis
increased urine flow rate
Micturition
urination/voiding bladder
At what volume do stretch receptors signal spinal cord and brain that bladder is full?
exceeds 200-400mL
Where are full bladder impulses sent to in the CNS?
micturition center in sacral spinal cord (S2 and S3)
The micturition reflex causes parasympathetic fibers to…
contract detrusor muscle
relax external and internal sphincter mueslces
