Excreção

Excreção is the biological process by which an organism eliminates metabolic waste products from its body. These waste products are byproducts of various cellular activities, primarily metabolism. Without efficient excretion, these substances can accumulate to toxic levels, disrupting bodily functions and potentially leading to death.

The primary function of excretion is to maintain homeostasis, the stable internal environment of the body. Different organisms have evolved diverse excretory systems tailored to their specific needs and environments. In many animals, the kidneys play a crucial role in filtering waste products from the blood and producing urine. Other animals may use specialized organs like Malpighian tubules in insects or flame cells in flatworms. Plants also excrete waste, often through processes like guttation, where excess water and dissolved minerals are released from leaf pores, or by shedding leaves and bark.

The nature of waste products varies. Common metabolic wastes include urea, ammonia, uric acid, carbon dioxide, and excess salts. The specific form of nitrogenous waste excreted often depends on the organism's habitat and water availability. For instance, aquatic animals may excrete ammonia, which is highly soluble in water, while terrestrial animals, needing to conserve water, often excrete urea or uric acid, which require less water for elimination.