Tubular Transport of NaCl and Water

Question 1

T/F: Most of the filtered water and salt is under homeostatic control.

Answer 1

F. Most of it is obligatorily reabsorbed.

Question 2

Where is nearly all of the obligatory recapture of salt and water performed?

Answer 2

In the proximal components.

Question 3

T/F: In normal individuals, it is possible to overwhelm the excretory capacity of the kidneys, with regards to water.

Answer 3

F. Unless there is an underlying decrease in GFR, or you’re a total jabroney, you can’t drink too much water.

Question 4

Na+ moves into the cells from the lumen via (active) or (passive) transport?

Answer 4

Passive.

Question 5

Na+ moves from the inside of the cell to the serosa via (active) or (passive) transport?

Answer 5

Active. Sodium is moved out by the Na/K ATPase

Question 6

How does chloride move from the lumen to the serosa?

Answer 6

Chloride moves through the gap junctions, accompanying sodium to maintain electrochemical equilibrium.

Question 7

How does water move from the lumen to the serosa?

Answer 7

Once Na and Cl are in the serosa, water follows the osmotic gradient.

Question 8

How does glucose move from the lumen to the serosa?

Answer 8

Glucose accompanies Na through the Na/Glucose cotransporter.

Question 9

What percentage of water and NaCl are reabsorbed in the proximal tubule?

Answer 9

65%

Question 10

How much water is reabsorbed in the descending LoH?

Answer 10

15%

Question 11

How much NaCl is reabsorbed in the ascending LoH?

Answer 11

25%

Question 12

T/F: Water can flow freely through the ascending LoH?

Answer 12

F. The ascending LoH is water-impermeable.

Question 13

Where are is all of the filtered glucose, bicarbonate, and amino acid reabsorbed?

Answer 13

In the proximal tubule

Question 14

Glucosuria is seen in _____, and happens when the _____ exceeds the ____.

Answer 14

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.

Question 15

What part of the nephron is sensitive to aldosterone and ADH?

Answer 15

The distal tubule and collecting duct.

Question 16

T/F: Water follows salt reabsorption in the ascending LoH

Answer 16

F. The ascending LoH is impermeable to water.

Question 17

The absorption of NaCl in the ascending limb involves the use of the ________ cotransporter?

Answer 17

Na/K/2Cl

Question 18

Where does regulated reabsorption of water and NaCl happen?

Answer 18

In the distal tubule and collecting duct. Coincidentally, the same places that are sensitive to ADH and aldosterone.

Question 19

Is sodium reabsorption upregulated or downregulated by aldosterone?

Answer 19

Upregulated.

Question 20

How does aldosterone upregulate sodium reabsorption in the fine-tuning segments?

Answer 20

Aldosterone increases the number of apical sodium channels and basolateral Na/K pumps.

Question 21

How does altosterone function in the cell to induce expression of additional pumps?

Answer 21

It works like every other steroid hormone. It goes nuclear and and turns on genes.

Question 22

The presence of ADH ______ water movement from the lumen.

Answer 22

Increases.

ADH is anti-diuretic hormone. Diuretics make you pee, so ADH pulls water out of the lumen and you pee less.

Question 23

How do the reabsorbed water and solute re-enter the capillary and systemic blood flow?

Answer 23

Through bulk flow, driven primarily through osmotic pressure.