There are several ways to dispose of harmful substances.
Egestion is the process by which food that has not been able to be digested is eliminated from the body through feces, ending its “journey” through the digestive system.
There is some confusion between this term and others such as “excretion”, “elimination” or “secretion”, which are often used interchangeably depending on the context.
In this article we will explain in detail what the process of egestion consists of, in addition to explaining the differences with other terms with which there may be confusion.
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removal of substances from the body
When we talk about the expulsion of substances in the body in a general way, the term to use is “elimination” , which simply implies that some substances that were previously in the body are no longer so through some process.
Eliminating certain accumulative elements in the body to avoid harmful effects that may occur as a result of their presence is essential for all forms of life.
From unicellular organisms, through plants and of course animals, all living beings are responsible for somehow discarding components that, if allowed to accumulate, could interfere with their vital functions.
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These waste substances have two main origins , depending on whether they are the result of the body’s normal metabolism (mainly metabolic by-products that are no longer usable, such as CO2 in animals) or if, on the contrary, they are ingested substances that have not been assimilated by the body and need to be expelled (This would be the case of the fiber, formed mainly by cellulose, which is not assimilable by humans).
In the case of metabolic waste products, we would mainly find nitrogenous molecules (such as ammonium, urea or uric acid), CO2 and water . All of them are part of the body’s natural metabolism but, if accumulated, they would produce harmful effects for the body, so their elimination is necessary.
The mechanisms by which the different living beings expel their waste substances depend both on the characteristics of the organism and on the type of substances that are being eliminated (a sponge, which eliminates its waste by diffusion, is not the same as a horse or a plant).
Understanding egestion: the end of our digestive process
Any animal with a complete digestive system will go through a more or less similar process. Food is ingested, it is processed along the digestive tract by the different organs (mouth, stomach, intestines…), where nutrients necessary for the continuation of life will be absorbed. The parts that have not been able to be used will be eliminated through the faeces.
Human feces are mainly made up of bacteria, fiber and other materials that could not be used during digestion, in addition to some hepatic metabolic products that are also discarded in this way, giving them their usual color.
Egestion is the process by which feces first accumulate in the final part of the large intestine, and then be expelled through defecation. This usually occurs between 36 and 48 hours after the ingestion of food and if it is slower, we could talk about constipation.
How is it different from excretion and secretion?
The role of egestion may have become clear to us, but to avoid misunderstandings we must also know the terms with which it is usually confused.
We have already commented that the term “disposal” is a wild card to speak in a generic way about waste management , but we can go deeper into the other two terms:
1. What is excretion?
Excretion is one of the terms that is most confused with egestion, but they are different processes. Excretion is our body’s way of getting rid of the metabolic byproducts we discussed earlier (some molecules with nitrogen, CO2, and water). This process occurs mainly thanks to the skin, the lungs and the kidneys .
The skin is responsible for eliminating part of the excess water through sweating, which in turn works to regulate the temperature of the body. The lungs expel excess CO2, which is carried by the blood to be eliminated by breathing. The kidneys are responsible for eliminating nitrogenous substances such as urea and ammonia, in addition to other toxic components that are also eliminated through the urine.
Excretion would then be a constant process, independent of food (unlike egestion), with which we eliminate non-solid residues derived from the natural metabolism of our body , to prevent them from accumulating and maintain homeostasis, normal physiological conditions.
2. What is discharge?
Secretion also refers to the expulsion of metabolic products from our cells , but unlike excretion, where the eliminated products are not used, these products usually have a use before they are discarded .
Examples of secretions would be digestive enzymes, such as those produced by the pancreas or intestine. Secretion implies that the substances that are being expelled from the cells have been synthesized by specialized cells and that they also have some valuable or necessary function for the organism.
Secretion differs from excretion and egestion in that the substances expelled in this process are of use to the body and have some function beyond preventing their accumulation in the body.
Bibliographic references
- Panawala, Lakna. (2017). Difference Between Ingestion and Egestion. Retrieved from Researchgate on 07/22/2019.
- Fenton Crosland Kelley, James Arthur Ramsay. (2018). Excretion. Retrieved from https://www.britannica.com/science/excretion on 07/22/2019.
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