Excretion Mammals excrete urine through the urinary system. Excretion is elimination of metabolic waste, which is an essential process in all organisms. In vertebrates, this is primarily carried out by the lungs, kidneys, and skin. [1] This is in contrast with secretion, where the substance may have specific tasks after leaving the cell.
Excretion is the biological process by which organisms eliminate metabolic wastes such as urea, ammonia, CO₂, excess water, and salts. Humans excrete waste through kidneys, lungs, liver, skin, and intestines, each specialized for different types of waste. This guide explains excretory products, human excretory organs, urine formation, excretory disorders, diagrams, FAQs, and NEET MCQs.