Which of the following is not considered a function of the kidneys?

The kidneys play a crucial role in maintaining homeostasis in the body, and each of the functions listed—secretion, reabsorption, and filtration—are integral to the renal process.

Secretion refers to the process by which the kidneys eliminate waste products and excess substances from the bloodstream into the urine. This is a vital function that helps regulate the body's chemical balance and removes toxins.

Reabsorption occurs after filtration in the nephron, where essential substances such as glucose, ions, and water are returned to the bloodstream. This process ensures that valuable nutrients and necessary amounts of water are not lost but rather conserved for the body's use.

Filtration is the initial step in urine formation, where blood is filtered in the glomeruli of the kidneys. This process removes waste products and excess substances from the blood, forming what is known as glomerular filtrate, which ultimately becomes urine.

Transport, on the other hand, is not a direct function of the kidneys themselves. While the kidneys facilitate the movement of substances (like reabsorbing nutrients and secreting waste), they are not primarily responsible for the transport of these substances throughout the body. Instead, transport is mainly carried out by blood vessels and the circulatory system, which distribute filtered and