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Excretory system

The excretory system is the system of an organism's body that performs the function of excretion, the bodily process of discharging wastes. It is responsible for the elimination of wastes produced by homeostasis. There are several parts of the body that are responsible for this process, such as the sweat glands, the liver, the lungs, and the kidney system. It removes wastes of the organism, balancing and regulating the chemical composition of its body fluids. The excretory system eliminates excretory products from the body, collects water and filters body fluids. Its parts include anything that aids in depleting wastes and unneeded substances. Without the excretory system, the build-up of harmful wastes could damage the body, resulting in destructive, dangerous, and even fatal consequences.

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Outline of the excretory system


The Excretory System: -Gets rid of wastes. -Eliminates useless by-products excreted from cells. -Eradicates harmful chemical build-ups. -Develops early in the womb. -Maintains a steady, balanced chemical concentration. -Conserves and gathers water from inside the body.

Kidneys and Nephrons

The kidneys and the nephrons, part of the urinary system, excrete urine. Urine contains any excess of calcium, unneeded chemicals that were ingested, and ammonia, a harmful chemical formed after the digestion of proteins. The kidneys contain the acidic urine, while the nephrons (inside the kidneys) monitor the water and soluble substances. Each kidney is made up of three sections: the renal cortex, the renal medulla, and the renal pelvis. The blood arrives at the kidney via the renal artery, which splits into many afferent arterioles. These arterioles, known as the glomerulus, go to the Bowman's Capsules, where the wastes are taken out of the blood by pressure filtration. It is connected to the nephron, where peritubular capillaries also surround it so substances can be taken in and out of the blood.

The renal cortex is the outer layer of the kidney and the medulla is the inner layer of the kidney. The renal pelvis takes urine away from the kidney via the ureter. Both of the ureters lead the urine into the body's only urinary bladder, which expands and sends nerve impulses when full. From there, urine is expelled through the urethra and out of the body.

The Nephrons monitor the water and soluble substances. They do this by filtering the blood through the renal corpuscle and containing and reacquiring beneficial substances. These are then submitted back into the blood flow of the body.


There are usually two kidneys in a common person’s body, even though having one is not considered to be detrimental to a person's heath. Instead, it would be considered an anatomical variation. The nephrons that filter the blood and recapture water and solutes in order to form urine are the main functional structural unit of the kidneys. They are held together so that the glomerulus constitutes the kidney's renal cortex. It is Henle's loop that gives the renal medulla it's characteristical color and radial lines.


Lungs are two-sponge like organs localized in each side of the thorax. They are constituted by pulmonary alveoli. They are not responsible for converting Oxygen into Carbon dioxide, but to maintain life supporting levels of these two gases in blood stream by excreting the extra carbon dioxide and keeping a regular supply of oxygen. Each and all organism's cells can take the oxygen through passive diffusion from the bloodstream and use it in its own metabolism, thus producing carbon dioxide that will be further excreted when passing through alveoli circulation.


The skin is another part of the system, containing sweat that help regulate the concentration in one’s body while also keeping him or her cool. The salt helps evaporate the water, cooling off the skin. Sweat is excreted through sweat glands. There are two types of sweat glands: Eccrine sweat glands and Apocrine sweat glands. The basic purpose of skin is to provide a waterproof, protective, covering for the body's complex internal environment.The skin also plays a key rules in helping to maintain the circulatory and nervous system.


The Eccrine glands secrete mostly water and salt and are used by the body for temperature control. These glands are located all around the body but are most profuse around the soles of the feet, palms of the hands, and the forehead. They look like coiled tubes, spiraling towards the exterior of the skin


The liver - a vital part of the excretory system, and the human body. It regulates glycogen storage, plasma protein synthesis, and drug detoxification. The liver secretes bile, a base used for breaking down fats. Therefore, it helps get rid of unneeded wastes in the body. The liver is the largest gland and the largest organ in the body.


Bile is a greenish or yellowish substance secreted by the liver used for breaking down fats, ethanol, and acidic wastes. It’s composed of water, cholesterol, lechithin, bicarbonate ions, bile salts, and pigments. Bile is a strong basic substance, classified as alkaline. It is released through bile ducts in the liver. A digestive chemical that is produce in the liver, stored in the gall bladder,and secreted in the small intestine.

Large Intestine

The large intestine, or the colon, is the last part of the excretory system. It is the organ that removes solid waste from the body. It’s function is not only to remove solid wastes, but to collect water from the waste that can be reused. It is part of the alimentary canal, a channel that flows through vertebrate animals. It is about 1.4 meters long and processes, transports, and excretes solid wastes.

    • Egestion/defecation (elimination of feces) is not an excretory process.

Works cited:

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Excretory_system". A list of authors is available in Wikipedia.
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