What filters at the glomerulus?
water, salts, glucose, urea
What does not filter at the glomerulus?
protein, blood cells,
What is reabsorbed in the proximal tubule?
100%: glucose, amino acids
90%: K, Ca, phosphate, bicarb, uric acid
66%: Na
passive: Cl, water, urea
How is urine concentrated in the loop of Henle?
- Descending limb and thin portion of the loop of Henle are freely permeable to water and salt
+ water flows out of the tubule, into the hyperosmotic interstitium
+ urine is concentrated: reduced volume, hypertonic - NaCl is actively reabsorbed into the thick ascending loop of Henle
+ segment is impermeable to water
+ urine becomes hypertonic as NaCl is pumped back into the medullary interstitium = urine volume is greatly reduced and is hypotonic
Where does ADH come from and act?
- synthesized by the hypothalamus and released from the posterior pituitary
- acts on the distal tubule and collecting ducts: increasing aquaporins and promoting reabsorption of water
Where does aldosterone come from and act?
- synthesized in the zona glomerulosa of adrenal cortex
- acts on late distal tubule and collecting duct to synthesize NaCl transporters
Where is the final regulation of water excretion and acid-base balance?
distal tubule and collecting ducts
Permeability of the distal tubule and collecting ducts to water is controlled by what?
ADH
Aldosterone stimulates _____ reabsorption in the ____________ and _________.
Na
late distal tubule
collecting ducts
Retention of ____ promotes water _______.
Na
reabsorption
___ is directly exchanged for Na.
K
Aldosterone promotes ___ loss.
K
Aldosterone is released in response to what 3 conditions?
Ang II / low blood pressure
hyponatremia
hyperkalemia
Aldosterone plays most important role in controlling ___ excretion and _____ _______.
Na
fluid volume
