The Final Composition of Urine is Represented by Which of the Following

Question

The final composition of urine is represented by which of the following statements?
A) Urine = substances reabsorbed + substances secreted.
B) Urine = substances filtered + substances reabsorbed + substances secreted.
C) Urine = substances secreted - substances reabsorbed - substances filtered.
D) Urine = substances filtered - substances reabsorbed + substances secreted.
E) Urine = substances reabsorbed - substances secreted - substances filtered.

Accepted Answer

Urine is the final product that is composed of substances that have been filtered by the kidney, some of the filtered substances are reabsorbed back into the bloodstream and some substances are secreted into the urine. Therefore, the final composition of urine is the sum of filtered substances minus reabsorbed substances plus secreted substances. Thus, choice D, "Urine = substances filtered - substances reabsorbed + substances secreted," represents the best statement of the final composition of urine.