Excreción

Excreción is the biological process by which an organism eliminates metabolic waste products and other non-useful materials from its body. This process is essential for maintaining homeostasis, the stable internal environment necessary for life. Waste products can include substances like urea, carbon dioxide, excess salts, and water. The specific methods of excretion vary greatly among different organisms and are adapted to their environments and physiological needs.

In animals, major excretory organs include kidneys, lungs, skin, and the digestive tract. Kidneys filter blood to remove waste products, forming urine, which is then expelled from the body. Lungs excrete carbon dioxide, a byproduct of cellular respiration. The skin can eliminate small amounts of waste through sweat. The digestive tract, while primarily involved in nutrient absorption, also expels undigested food material as feces.

Plants also excrete waste, though their methods differ. They may release gases like oxygen and carbon dioxide through stomata. Excess water is removed through transpiration. Some plants store waste products in their leaves, which are then shed, or in specialized vacuoles within cells. Microorganisms, such as bacteria and fungi, excrete waste products directly into their surrounding environment. The efficiency and mechanisms of excretion are critical for the survival and health of all living organisms.