Excretory System
Excretory System

Excretory System: Definition, and 5 Organs

Human Excretory System Definition

Excretory system in humans is a system that is responsible for processing and removing residual metabolic substances and toxins from the body. If not removed from the body, such substances can cause a number of health problems.

The excretory system in humans consists of a number of organs, namely the lungs, skin, liver, and kidneys. Each of these excretory organs has different functions and ways of working to remove residual substances and toxins from the body.

Excretory System Organs

The following are some organs that belong to the human excretory system along with the type of waste substances it disposes of:


The kidneys are the main organ of the human excretory system. This organ is located on both sides of the spine, precisely in the abdominal cavity of the back. The kidneys have a shape resembling red beans and are red-brown in color.

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Humans have a pair of kidneys located on the right and left sides of the body. The right kidney is located slightly lower than the left kidney because it is adjacent to the liver. Each kidney measures about 10–12 cm or approximately the size of an older person’s fist.

Kidneys function serve to filter residual substances from food, medicines, or toxins found in the blood. In addition, the kidneys also play a role in controlling fluid balance and electrolyte levels in the body. If your body is excess salt or minerals, the kidneys will also throw it away.

Residual substances collected, will then be converted into urine. Urine will flow from the kidneys to the bladder through a channel called the ureter. The urine contains residual substances from the kidneys that will be wasted when you urinate.


Human skin has about 3–4 million sweat glands. These glands are spread throughout the body, but are most common in the palms, feet, face, and armpits.

Sweat glands are divided into 2 types, namely eccrine glands and apocrine glands. The eccrine gland is directly connected to the surface of the skin and produces odorless and diluted sweat. Meanwhile, apocrine glands produce sweat containing fat and concentrated, and are present in hair follicles, such as the armpits and scalp.

Basically, the sweat produced by these glands serves to control body temperature and lubricate the skin and hair. However, as part of the excretory system, sweat glands also play a role in removing toxins from the body through the sweat it produces.

There are several types of toxins that are removed through the sweat glands in the skin, including metal substances, bisphenol A, polychlorinated biphenyls, urea, phthalate, and bicarbonate. Not only toxins, sweat glands in the skin also serve to eradicate and remove bacteria.


Basically, the intestine is divided into 2 parts, namely the small intestine and colon. Most of the nutrients and about 90% of the water contained in the foods and drinks consumed daily are absorbed into the small intestine.

Meanwhile, the colon is responsible for absorbing residual water and nutrients that cannot be digested by the small intestine. After being absorbed, the rest of the food and drink are converted into feces, then disposed of through the rectum when you defecate.


The liver is a large organ weighing about 1 kilogram. This very important organ for metabolism and the immune system is located at the upper right in the abdominal cavity, just below the diaphragm.

One of the toxic substances discarded and processed by the liver is ammonia, which is the residual substance from the decomposition of proteins. If left to accumulate in the body, ammonia can cause a variety of health disorders, including respiratory disorders and problems with the kidneys.

In the body, the liver serves to process the ammonia into urea. After that, the processed urea in the liver will be removed through the Excretory system in the kidneys through urine. In addition to ammonia, other substances discarded or excreted by the liver are toxic substances in the blood, for example, due to the consumption of alco**hol or drugs.

Liver organs also serve to remove damaged red blood cells and excess bilirubin that can cause jaundice.


The lungs are the main organ in the human respiratory system. Through the respiratory process, the lungs are tasked to transfer the oxygen obtained from the air into the blood. Blood that has contained oxygen will be distributed to all tissues and organs in order to function properly.

After obtaining oxygen, each cell of the body will produce carbon dioxide as the remaining substance of its metabolism. Carbon dioxide is a toxic substance that can be harmful to health when it accumulates in the blood.

To dispose of it, carbon dioxide will be carried by blood back towards the lungs and removed when you exhale.

Coughing or sneezing is also a natural mechanism of the body that involves the lungs and airways to expel toxic chemicals or gases, dust, germs, viruses, and foreign objects that enter the respiratory system.


Last Updated on January 16, 2022 Reviewed by Market Health Beauty Team