23. Concentrating the Urine

Countercurrent Multiplier

Mechanism enhancing urine concentration in kidneys.

Loop of Henle

U-shaped segment of nephron for urine concentration.

Isotonic Medullary Interstitium

Equal osmotic pressure with loop of Henle.

Active Transport

Energy-driven ion movement, primarily NaCl.

Ascending Limb

Segment where NaCl is actively transported out.

Descending Limb

Segment allowing passive water diffusion out.

Osmotic Pull

Water movement driven by solute concentration differences.

Hyperosmotic Medullary Interstitium

Region with higher solute concentration than surrounding fluid.

Vasa Recta

Capillary network surrounding the loop of Henle.

Countercurrent Exchanger

Mechanism allowing solute exchange in opposite directions.

Concentration Gradient

Difference in solute concentration across a space.

Medullary Interstitium

Space between renal tubules in the kidney medulla.

Desert Gerbil Kidney

Adapted with long loops of Henle for water conservation.

Urine Concentration

Process of increasing solute concentration in urine.

Passive Diffusion

Movement of water without energy expenditure.

Tubule Fluid Concentration

Increasing concentration as fluid moves through nephron.

Kidney Adaptation

Structural changes for enhanced water retention.