How can urine contain a higher concentration of wastes (be hypertonic)than the blood?
A)Urine cannot since the process is passive diffusion.
B)Reabsorption of water in the loop of the nephron and collecting ducts leaves behind a more concentrated urine.
C)All stages in the kidney involve active transport.
D)Urine can be hypertonic for small molecules if it is hypotonic for an equal number of big molecules.
E)The whole nephron is impermeable to water.

Question

Quizplus · Accepted Answer

Reabsorption of water in the loop of the nephron and collecting ducts leaves behind a more concentrated urine. The kidney actively reabsorbs water from the filtrate in the loop of the nephron and collecting ducts, leaving behind a more concentrated urine with a higher concentration of wastes than the blood. This process is facilitated by the reabsorption of ions such as sodium, chloride, and potassium, which creates an osmotic gradient that draws water out of the filtrate and into the surrounding tissue. The resulting urine is hypertonic with respect to the blood.

How Can Urine Contain a Higher Concentration of Wastes (Be