Tubular Transport of NaCl and Water Flashcards
(23 cards)
T/F: Most of the filtered water and salt is under homeostatic control.
F. Most of it is obligatorily reabsorbed.
Where is nearly all of the obligatory recapture of salt and water performed?
In the proximal components.
T/F: In normal individuals, it is possible to overwhelm the excretory capacity of the kidneys, with regards to water.
F. Unless there is an underlying decrease in GFR, or you’re a total jabroney, you can’t drink too much water.
Na+ moves into the cells from the lumen via (active) or (passive) transport?
Passive.
Na+ moves from the inside of the cell to the serosa via (active) or (passive) transport?
Active. Sodium is moved out by the Na/K ATPase
How does chloride move from the lumen to the serosa?
Chloride moves through the gap junctions, accompanying sodium to maintain electrochemical equilibrium.
How does water move from the lumen to the serosa?
Once Na and Cl are in the serosa, water follows the osmotic gradient.
How does glucose move from the lumen to the serosa?
Glucose accompanies Na through the Na/Glucose cotransporter.
What percentage of water and NaCl are reabsorbed in the proximal tubule?
65%
How much water is reabsorbed in the descending LoH?
15%
How much NaCl is reabsorbed in the ascending LoH?
25%
T/F: Water can flow freely through the ascending LoH?
F. The ascending LoH is water-impermeable.
Where are is all of the filtered glucose, bicarbonate, and amino acid reabsorbed?
In the proximal tubule
Glucosuria is seen in _____, and happens when the _____ exceeds the ____.
Beetus; rate of filtration; transport maximum.
This happens when there’s too much sugar in the blood, and the kidneys cannot remove it all from the tubules.
What part of the nephron is sensitive to aldosterone and ADH?
The distal tubule and collecting duct.
T/F: Water follows salt reabsorption in the ascending LoH
F. The ascending LoH is impermeable to water.
The absorption of NaCl in the ascending limb involves the use of the ________ cotransporter?
Na/K/2Cl
Where does regulated reabsorption of water and NaCl happen?
In the distal tubule and collecting duct. Coincidentally, the same places that are sensitive to ADH and aldosterone.
Is sodium reabsorption upregulated or downregulated by aldosterone?
Upregulated.
How does aldosterone upregulate sodium reabsorption in the fine-tuning segments?
Aldosterone increases the number of apical sodium channels and basolateral Na/K pumps.
How does altosterone function in the cell to induce expression of additional pumps?
It works like every other steroid hormone. It goes nuclear and and turns on genes.
The presence of ADH ______ water movement from the lumen.
Increases.
ADH is anti-diuretic hormone. Diuretics make you pee, so ADH pulls water out of the lumen and you pee less.
How do the reabsorbed water and solute re-enter the capillary and systemic blood flow?
Through bulk flow, driven primarily through osmotic pressure.
