What organ is primarily responsible for producing urine?

The kidney is the organ primarily responsible for producing urine. It plays a crucial role in the body's filtration system by removing waste products and extra fluids from the blood. This process begins in the nephrons, the functional units of the kidney, which filter out waste and excess substances, resulting in the formation of urine. Once produced, urine is then transported to the bladder for storage until it is excreted from the body.

The liver, while vital in metabolic processes and the detoxification of substances, does not produce urine. Instead, it processes nutrients and produces bile. The bladder serves as a storage organ for urine but does not produce it, and the ureter is simply a tube that carries urine from the kidney to the bladder. Understanding the distinct functions of these organs clarifies the central role of the kidneys in urine production.