Final answer:
The kidneys create urine, a waste-filled liquid that consists of water, salts, and nitrogen-containing molecules like urea, which are filtered from the blood to maintain the body's internal balance.
Step-by-step explanation:
The kidneys create a waste-filled liquid known as urine. This complex fluid is excreted by the kidneys and is composed of many toxic substances that are removed from the blood. Urine consists mostly of water, but also contains salts, nitrogen-containing molecules like urea, and other metabolic wastes. The role of the kidneys is crucial because they continuously filter these waste products from the blood to form urine, which then passes through the nephrons and is carried to the bladder via the ureters.
Urine production is directly related to bodily fluid intake and loss. Factors like hydration, food consumption, sweating, and respiration impact the volume and concentration of urine. If not for the process of urination, these waste substances would accumulate in the bloodstream and cause harm to the body. Therefore, the excretory system, with the kidneys at its core, plays a vital role in maintaining the body's internal balance and overall health.