Tubular reabsorption

Passive transport

is the movement of molecules across a membrane as a result of differences in their concentration or electrical potential on opposite sides of the membrane.

Gradients

These physical differences [in concentration or electrical potential] are called ________

renal threshold

The plasma concentration at which active transport stops is termed the

160 to 180~mg/dL

For glucose, the plasma renal threshold is ________, and glucose appears in the urine when the plasma concentration reaches this level.

active transport; passive transport

The cellular mechanisms involved in tubular reabsorption are termed ________ and ________.

active transport

_______ the substance to be reabsorbed must combine with a carrier protein contained in the membranes of the renal tubular epithelial cells. The electrochemical energy created by this interaction transfers the substance across the cell membranes and back into the bloodstream.

Chloride; Sodium

According to Table 4-1, ________ is reabsorbed via active transport in the ascending loop of Henle, while ________ is reabsorbed via passive transport in the ascending loop of Henle.

Passive transport of Water

Proximal convoluted tubule, Descending loop of Henle, Collecting duct.

same concentration

The fluid leaving the proximal convoluted tubule still maintains the ________ as the ultrafiltrate.

two-thirds; equal amount of water

Active transport of more than ________ of the filtered sodium out of the proximal convoluted tubule is accompanied by the passive reabsorption of an ________.

sodium; chloride

Passive reabsorption of ________ accompanies the active transport of ________ in the ascending loop.

Urea

________ is passively reabsorbed in the proximal convoluted tubule and the ascending loop of Henle.

water; ascending loop of Henle

Passive reabsorption of ________ takes place in all parts of the nephron except the ________, the walls of which are impermeable to water.

glucose; amino acids; salts

Active transport is responsible for the reabsorption of ________, ________, and ________ in the proximal convoluted tubule.

Renal Threshold

can be used to distinguish between excess solute filtration and renal tubular damage.