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Excretion and Its Importance

Excretion and its Importance

All life forms have a biological need to get rid of unwanted materials referred to as waste. The process by which organisms eliminate their metabolic waste is known as excretion. It is how a life form dispenses off its waste depending on its physiology and biology. Still, there is no denying that excretion is an essential process for all organisms.

For example, unicellular life forms discharge their waste directly from the surface of their cell. At the same time, complex organisms like humans have an elaborate excretory system that removes waste through urine and feces. The common thread that links all these life forms is that they undergo the biological process of excretion in one way or another.

Fig 1 Human Urinary System


The Biological Understanding of the need for Excretion:

All living organisms are made up of cells, and many chemical reactions take place inside these cells, which is referred to as metabolism. Waste materials like water, carbon dioxide, urea, uric acid, etc., are released into the body during metabolism. These materials are unwanted by the body and are toxins that should not accumulate in the body. Hence, excretory organs are primarily concerned with getting rid of this metabolic waste from the body.

Fig 2- Kidney Anatomy


Importance of Excretion:

Imagine the human body is like an internal combustion machine. Energy is taken into this machine in the form of fuel to be burned inside the system, and the energy generated can be used to power the pistons in the machine. However, this machine does not utilize all the fuel, so the unnecessary part is released in gases like Carbon dioxide, Carbon monoxide, etc.

However, if these gases were not allowed to leave the machine, they would clog other parts of the machine, in turn decreasing its overall efficiency and, in some cases, even resulting in a complete breakdown. Thus, by analyzing the example of a machine, it is simple to understand why an exhaust system exists to dispel unnecessary gases. The human body is analogous to such a machine, as humans and other animals too must take in energy- containing compounds like food, water, and oxygen. The organism's cells then use a part of this energy to fuel life processes like breathing, walking, thinking, etc.

However, like the engine, the human body also creates unusable substances or by-products of this process that it does not need. Such materials need to be released from the body before they accumulate and cause damage to its ordinary functioning, and the process by which the body does this is excretion.

The Consequences of a System that does not Excrete

If the waste disposal system of an organism were completely blocked, its consequences on the body would be as catastrophic as stopping the body’s food, oxygen, and water supply. Moreover, the metabolic process also releases toxins that are so harmful that they must be released from the body as soon as they are created by the cells. Hence the excretory functions of a body need to work continuously so that other chemical processes taking place inside an organism can work too. An overview of the eliminatory mechanism of the human body The waste materials released by the body can be categorized into two types:

  • 1. Metabolic
  • 2. Non-metabolic


Metabolic waste is generated because of the chemical processes of a cell.


In contrast, non-metabolic waste comprises those elements which cannot be used by the body and hence pass through the digestive tract of the living being.

Elimination Mechanisms

The human body releases these two types of waste through:

  • 1. Respiratory System,
  • 2. The Kidneys,
  • 3. The Alimentary Canal.

Respiratory System

The respiratory system primarily dispenses the gaseous metabolic waste of the body using the passive method of breathing that does not require much energy.


On the other hand, kidneys are more complex methods for waste disposal that regulate the water and salt content of the body, and the waste is released in the form of urine.

Alimentary Canal

Lastly, the alimentary canal is used only to eliminate solid waste that the body cannot digest. Such waste is pushed out of the body with the help of the digestive system. Understanding the way different organisms and humans get rid of waste from their systems is essential. The excretion process is vital to get rid of unnecessary material from the body and ensure the smooth functioning of other life processes. Every organism excretes in some form or the other, and in human beings, this process involves the above mentioned three mechanisms.

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