Chapter 24, Problem 14CYR

Summary Introduction

To review:

The given blank space in the statement“The kidneys produce_____urine when the osmolarity of the body’s fluids increases. They produce_____ urine when osmolarity of the body’s fluids decreases.”

Introduction:

The filtrate that enters the renal tubule through the renal corpuscle is iso-osmotic. Its concentration is equal to the plasma concentration of 300 mOsm (milliosmolar). The osmolarity of the filtrate changes in the loop, mainly because of the reabsorption of water, sodium and chloride ions (Na⁺ and Cl^-), and a significant portion of other ions. Reabsorption and secretion occur due to the differences in the permeability of the ascending and descending limbs of the loop.