Mastering A&P Urinary System Practice Test

A decrease in the medullary gradient leads to the production of dilute urine due to the relationship between the osmotic gradient in the renal medulla and the kidneys' ability to concentrate urine. The medullary gradient is essential for the reabsorption of water during urine formation.

In a healthy functioning kidney, the medulla has a high osmolarity, which allows for water to be reabsorbed from the renal tubules back into the bloodstream, leading to concentrated urine when the body needs to conserve water. However, when the medullary gradient decreases, there is a reduced capability for the kidneys to draw water from the tubular fluid. Consequently, less water is reabsorbed, resulting in a higher volume of urine that is more diluted. This means that the urine has a lower concentration of solutes, which is characteristic of dilute urine production.

Thus, the correct outcome of a decreased medullary gradient is the formation of dilute urine, reflecting how renal function adapts to changes in osmotic balance.