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Difference between Excretion and Egestion

The human body is a varied mechanism. The combination of veins, arteries, capillaries, muscles, white blood cells, red blood cells, etc., makes the human body. In general terms, the human body is nothing but an accumulation of food and water. The food and water that we intake make the strength of the body. The body remains in a stable position due to the food we eat. Eating is an intrinsic process. Another important process is excretion. It is essential for the food to come out of the body that we eat. The waste material must come out of the body in order to make it healthy and stable. Now, there are many processes associated with the body. Today we will be discussing about two such processes, i.e., excretion and egestion. Many of us are often confused about these two terms as they mean somewhat the same. But it is not so. They both are different in some aspects. So, let us first look at the definition of excretion and egestion.


Excretion is defined as the process wherein metabolic waste is released from the body. In vertebrates, this process is carried out through lungs, skin, kidneys, etc. Excretion is necessary for all life forms. For example, urine is excreted through the urethra in mammals. Thus, the urethra is a part of the excretory system.

Similarly, the waste is excreted through the cell's surface in unicellular organisms. The body of an animal or a human consists of metabolism. Now, what is metabolism? Several chemical reactions take place in the body during cellular respiration. These reactions are called metabolism. The chemical reactions produce many waste materials like carbon dioxide, salt, urea, water, uric acid, etc. These chemicals are accumulated in the body that is very harmful. Therefore, it becomes necessary to extract this waste from the body. That is why the process of excretion is essential. The process of extracting/ releasing the metabolic waste from the body is known as excretion. In plants, waste material like water and carbon dioxide is excreted through stomata and root cell walls. This waste material is released during respiration. In animals, the waste materials like ammonia, carbon dioxide, guanine, uric acid, etc., are released through the liver and kidneys. The liver and kidneys extract almost all waste material. But the remaining waste materials are released through feces and urine. Well, there are several kinds of excretion, namely ammonotelism, ureotelism, aminotelism, guanotelism, etc., which we will discuss later.


Egestion is defined as the process of excretion of undigested food from the body. In single-celled organisms, the waste material is released through a cell, while in multi-cellular organisms, the waste material is extracted through the digestive tract. Egestion is also known as defecation. Egestion takes place when the absorption is completed in the body. The waste material that is stored in the large intestine passes through the rectum and is released by the body through the anus. Well, egestion is not considered to be excretion. This is so because egestion involves the extraction of undigested food from the body. Excretion is the extraction of waste material. Therefore, egestion cannot be related to excretion. Both are different in some aspects. So, let us discuss the contrasting points between them.

1. Excretion is defined as the process of extracting metabolic waste from the body. On the other hand, egestion is defined as the exaction of undigested food from the body.
2. Excretion takes place in plants, animals, and humans. Egestion takes place in single-celled and multi-celled organisms.
3. The waste materials in the body are released during cellular respiration. Egestion does not include waste material; rather, it involves undigested food.
4. The waste materials are released through the cell's surface, stomata, root cells, nose, skin, urethra, etc. The undigested food is released through the anus in the form of solid or semi-solid matter. Aquatic animals like jellyfish release and consume through their mouth.
5. Excretion is the process of releasing metabolic waste like carbon dioxide, oxygen, etc. Undigested material is released from the body. The undigested matter is egested in the form of feces.
6. Excretion is a completely different process and is essential for all life forms. Egestion is a part of the process of digestion.

So, these are some contrasting points between excretion and egestion. However, both processes are essential as they extract the waste material from the organisms. Excretion and egestion are the fundamental aspects of life. If these processes do not take place, then they can be harmful to the organisms. Now, excretion and egestion have certain advantages/ importance. So, let us take a look at them.

Importance of Excretion

  1. Excretion is firstly seen in plants that produce water as a respiratory product. Next, plants excrete through the process of guttation and transpiration.
  2. Carbon dioxide is extracted/ released by humans. This chemical is used by plants for the process of photosynthesis.
  3. In plants, the vacuoles generate metabolic waste. As a result, these vacuoles get filled, and the leaf is dropped. This is known as excretophores.
  4. In humans, excretion takes place when the toxins accumulate in the body. Sweating is one kind of excretion that takes place in the human body.
  5. Unicellular organisms (amoeba) also release metabolic waste through the process of diffusion.
  6. Other organisms like viruses and bacteria do consume nutrients or release waste from their bodies.

Importance of Egestion

  1. The undigested food is discharged from the body through the process of egestion.
  2. It is a vital process and is the fundamental basis for all life forms.
  3. If the egestion process does not take place, it can lead to bowel rupture, which can prove to be fatal.
  4. In single-celled organisms, the egestion takes place through the cell's surface, while in the multi-celled organisms, it takes place through digestive tracts.
  5. The waste material during egestion is extracted through the anus.

So, these are some points regarding the egestion and excretion. Both these processes take place in multi-celled and single-celled organisms. These processes need to happen; otherwise, the body can be affected in a negative way. Thus, egestion and excretion are essential for organisms.

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