Why is the excretory system necessary

Figure 1. Just as humans recycle what we can and dump the remains into landfills, our bodies use and recycle what they can and excrete the remaining waste products. Improve this page Learn More. Skip to main content. Module The Excretory System. Nephrons filter materials out of the blood, return to the blood what is needed, and excrete the rest as urine. As shown in Figure By producing and excreting urine, the kidneys play vital roles in body-wide homeostasis.

They maintain the correct volume of extracellular fluid, which is all the fluid in the body outside of cells, including the blood and lymph. The kidneys also maintain the correct balance of salts and pH in extracellular fluid. In addition, the kidneys function as endocrine glands, secreting hormones into the blood that control other body processes.

You can read much more about the kidneys in section Why can we regrow a liver but not a limb? Are sports drinks good for you? Fit or Fiction. Why do we sweat? A set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate ATP.

A compound of nitrogen and hydrogen with the formula NH3. It is a common nitrogenous waste produced by the breakdown of amino acids in various cells in the body. Waste product of protein catabolism that is mainly filtered from blood in the kidneys and excreted in urine. A waste product of nucleic acid catabolism that is mainly filtered from blood by the kidneys and excreted in urine. The major organ of the integumentary system that covers and protects the body and helps maintain homeostasis, for example, by regulating body temperature.

An organ of digestion and excretion that secretes bile for lipid digestion and breaks down excess amino acids and toxins in the blood. An organ of the digestive system that removes water and salts from food waste and forms solid feces for elimination. Two paired organs of the respiratory system in which gas exchange takes place between the blood and the atmosphere. One of a pair of organs of the excretory and urinary systems that filters wastes and excess water out of blood and forms urine.

The body system responsible for the elimination of wastes produced by homeostasis. There are several parts of the body that are involved in this process, such as sweat glands, the liver, the lungs and the kidney system.

From there, urine is expelled through the urethra and out of the body. Salty fluid secreted into ducts by sweat glands in the dermis that excretes wastes and helps cool the body; also called perspiration. Fluid produced by the liver and stored in the gall bladder that is secreted into the small intestine to help digest lipids and neutralize acid from the stomach. A multi-branched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria.

A brown pigment secreted into bile by the liver that is a byproduct of catabolism of dead red blood cells and is excreted in feces by the large intestine. Solid waste that remains after food is digested and that is eliminated from the body through the anus.

One of a cluster of tiny sacs at the ends of bronchioles in the lungs where pulmonary gas exchange takes place. A liquid waste product of the body that is formed by the kidneys and excreted by the other organs of the urinary system. One of the million tiny structural and functional units of the kidney that filters blood and forms urine.

A long, narrow, tube-like organ of the digestive system where most chemical digestion of food and virtually all absorption of nutrients take place. The urinary system maintains an appropriate fluid volume by regulating the amount of water that is excreted in the urine.

Other aspects of its function include regulating the concentrations of various electrolytes in the body fluids and maintaining normal pH of the blood. In addition to maintaining fluid homeostasis in the body, the urinary system controls red blood cell production by secreting the hormone erythropoietin. The urinary system also plays a role in maintaining normal blood pressure by secreting the enzyme renin.