excrétons

Excrétions are waste products of metabolism that are eliminated from an organism. These substances are typically toxic or in excess and must be removed to maintain homeostasis and overall health. The primary organs involved in excretion in mammals are the kidneys, which filter blood and produce urine. Other excretory organs include the lungs, which remove carbon dioxide, and the skin, which eliminates sweat containing salts and urea. The liver also plays a role by detoxifying harmful substances and converting them into less toxic forms that can be excreted.

The composition of excretions varies depending on the organism and its diet. In terrestrial animals, water conservation is often a key factor, leading to different forms of nitrogenous waste. For example, mammals excrete urea, which is less toxic and requires less water for elimination than ammonia, the primary nitrogenous waste of many aquatic animals. Birds and reptiles, on the other hand, excrete uric acid, which is a semi-solid paste that requires very little water.

Disruptions in the excretory system can lead to serious health consequences. Accumulation of waste products in the body can cause poisoning and organ damage. For instance, kidney failure prevents the effective removal of toxins from the blood, necessitating treatments like dialysis. Understanding the process of excretion is fundamental to comprehending physiological balance and the impact of disease on the body.