Role of Other Organs in Excretion

The primary excretory organs, including the kidney, urinary bladder, and others, have a variety of roles in excretion.

• Some other organs like Lungs, Salivary Glands, and Skin act as excretory organs.
• There are various excretory substances produced by these excretory organs- Sweat, Saliva, Urine, etc.
• These substances are harmful if kept for a long time inside the body.
• The Excretory organs remove these unwanted substances from the body and prevent serious diseases. 

Key Terms: Excretion, Role of kidneys in excretion, Kidneys, Lungs, Liver, Sweat glands, Skin, Intestine, and GI Tract. 

What is Excretion? 

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Excretion is an important biological process that occurs in the body. Through this process, unwanted substances and metabolic wastes 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. 

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Role of Kidney in Excretion 

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Kidneys are 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.
• They 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. 
• The diagram of the kidney is shown here for better understanding.

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Role of Liver in Excretion 

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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 excreted outside through feces. 

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Other Excretory Organs in Body 

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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

Lungs are the major excretory organ for the removal of carbon dioxide and water from our body through the air that we remove 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

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
• They help in the elimination of certain waste substances through their secretions. 
• Excess water, salts, and urea, a consequence of protein catabolism, are expelled by sweating.

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.
• This fluid contains lactic acid, urea, and sodium chloride which helps in ,cooling the body and eliminating some of the wastes from the body. 
• Sweat regulates body temperature by cooling the skin's surface when the water in the perspiration evaporates.

Sebaceous Glands

Sebaceous glands attached to the hair follicle secrete 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. 
• This produced sebum aids in keeping moisture in and shields skin from drying out.

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. 
• Saliva maintains healthy teeth, keeps the mouth moist, and helps with digestion.

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, tear glands get activated.
• They excrete a substance from the eyes with the help of tears to protect our eyes. 
• Substances released from the tear gland are electrolytes, water, proteins, and mucins.

Intestine and GI Tract 

Feces are the important excretory wastes produced by our body apart from Urine excreted outside of 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 are also eliminated through feces by our body. 
• Food waste is converted into excrement, stored there, and then expelled through the large intestine, also known as the big bowel.

 

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Things to Remember 

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• Excretion removes unwanted substances which are present in excess amounts and the metabolic wastes produced during various biochemical reactions are eliminated from the body.
• Liver is the largest gland in our body that secretes bile pigments like biliverdin, biliverdin, cholesterol, degraded steroid hormones, vitamins, drugs, etc.
• Some of the organs other than the kidney also perform a role of excretion called accessory organs of excretion. 
• Lungs, Skin, Salivary Glands, Intestine, and GI Tract are some other organs that help in excretion. 
• 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. 

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