User:Bluecow4321/New sandbox
From Wikipedia, the free encyclopedia
Excretion is a process in which metabolic waste is eliminated from an organism.[1] This is in contrast with secretion, where the substance may have specific tasks after leaving the cell. Excretion is an essential process in all forms of life. For example, the waste products of unicellular organisms are discharged directly through the surface of the cell by diffusion. Plants have simple excretion methods to dispose of oxygen and excess water. The disposal of waste products in animals differ across species, with the release of different chemicals through specialized organs. In vertebrates, this is primarily carried out by the lungs, kidneys, and skin.
During life activities such as cellular respiration, several chemical reactions take place in the body. These reactions are commonly known as metabolism. These chemical reactions produce waste products such as carbon dioxide, water, salts, urea and uric acid. The excretory organs will remove these wastes. Accumulation of these wastes beyond a level inside the body is harmful and can cause a variety of diseases within the excretory system. This process of removal of metabolic waste from the body is known as excretion. Excretion can also be quantified using what is known as fractional excretion.