Role of Different Organs in Excretion – Class 11 | Chapter – 19 | Biology Short Notes Series PDF

Role of Different Organs in Excretion: Excretion is an important biological process that occurs in the body by which unwanted substances which are present in excess amounts and the metabolic wastes produced during various biochemical reactions are eliminated from the body. Substances that are needed to be excreted from the body are- Nitrogenous wastes, Carbon dioxide, Water, Excess salts, water, and many more. Our excretory system helps in performing excretion in addition to the elimination of wastes and toxins it also helps in maintaining the osmoregulation of our body to maintain homeostasis. 

Role of Different Organs in Excretion

Role of Kidney in Excretion

Kidneys is bean-shaped, reddish-brown structures present close to the dorsal inner wall of the abdominal cavity between the levels of the last thoracic and third lumbar vertebra. The average weight of the Kidney of an adult is approximately 120-170 gm. 

Kidneys are protected by the last two ribs of the backbone and help in the elimination of nitrogenous wastes from the body in the form of Urine. The nephron is the structural and functional unit of the kidney that participates in the removal of wastes from the blood.

Kidneys are the main organs of excretion in humans. Apart from kidneys, other organs like lungs, liver, skin and sebaceous glands also help in excretion.

Role of Liver in Excretion

Liver is the largest gland in our body that secretes bile pigments (biliverdin, biliverdin, cholesterol, degraded steroid hormones, vitamins, drugs, etc.). Bile is the excretory product produced in the liver due to the breakdown of hemoglobin in the worn-out cells in the liver to maintain chemical levels in the blood. The liver helps in the conversion of ammonia into less toxic urea which excretes in the form of Urine through the Kidneys. The liver is also known as the graveyard of RBCs, the byproducts of RBC destruction, and hormone metabolites are all synthesized in the liver and excrete outside through feces. 

Other Excretory Organs in Body

Some of the organs other than the kidney also perform a role of excretion called accessory organs of excretion. Apart from the excretion, they perform other functions as well. Lungs, Skin, Salivary Glands, Intestine, and GI Tract are some other organs that help in excretion. 


Lungs are the major excretory organ for the removal of carbon dioxide and water from our body through the air that we remove out by expiration. These organs are mainly involved in respiration and the elimination of gaseous wastes from the body. 

Our lungs eliminate large amounts of CO2 (approximately 200ml/minute) and water in the form of water vapors (approximately 400 ml/day) from the body. The amount of water eliminated by the lungs depends on the temperature of the environment and the condition of the body. 


Skin is the largest organ of the body primarily involved in the regulation of body temperature, protection from harmful pathogens, and protection of body parts from sunlight and harsh environmental conditions. Skin layers contain two types of glands: Sweat Glands and Sebaceous Glands that help in the elimination of certain waste substances through their secretions. 

Sweat Glands

Sweat glands are located in the dermis of the skin and primarily help in maintaining the temperature of the body. In summer when it is too hot outside, sweat glands secrete sweat which is a watery fluid containing lactic acid, urea, sodium chloride which helps in cooling the body and eliminating some of the wastes from the body. 

Sebaceous Glands

Sebaceous glands attached to the hair follicle secretes sebum, which is not a watery secretion. Sebum contains substances like sterols, hydrocarbons and waxes, and also some lipid wastes. Sebaceous glands eliminate excess fats and waxes in the form of sebum, outside of the body. 

Salivary Glands

Salivary glands secrete saliva which contains water, mucous, and also a little amount of urea as an excretory product. It is situated in the buccal cavity and its watery secretion contains enzymes that help in food digestion. Salivary glands also help in the excretion of some heavy metal ions like mercury and lead. 

Tear Glands

These are the lacrimal glands found in the eyes that help in the excretion of some amounts of urea and wastes in the form of tears from the eyes. Whenever dust or any harmful substance comes in contact with the eyes our tear glands get activated and try to excrete that substance from the eyes with the help of tears to protect our eyes. 

Intestine and GI Tract 

Faeces are the important excretory wastes produced by our body apart from Urine to excrete outside from the body. Faeces are the solid wastes eliminated by our body via the rectum produced primarily by the intestines. Some of the excess wastes like- Fibres, salts, glucose, and minerals like calcium and iron are also eliminated through faeces by our body. 

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By Team Learning Mantras