Egestion: Mechanism, Disorder, Excretion and Digestion Process

Egestion, also called defecation, is the final act of digestion by which elimination of solid, semisolid and liquid waste moves out from the anus. Egestion is the final process of digestion. The undigested or waste materials left in our body after the extraction of the nutrients from the food is discharged out of our body in the form of faeces. 

Key Takeaways: Egestion, Defecation, Anus, Digestion process, Excretion process, Organs

---

Egestion Definition

[Click Here for Sample Questions]

Egestion is a process of discharging food which is not digested, from the living body in the form of feces. Passing out of undigested food as feces or stool from the body is called Egestion. Elimination of faecal which is formed by non digested food along with water and excess of digestive enzymes.

Undigested food is absorbed in the colon and changes into faces which are temporarily stored in the rectum i.e. the last part of the digestive part where more is absorbed. The faces are finally expelled through anus.

In Egestion, waste is from the fibre rich foods that we eat. Fibre passes through the digestive tract without any changes i.e. no digestion of enzymes. Waste is in the form of feces or in general we call stool.

Egestion

Egestion Mechanism

The symbiotic bacteria uses the roughage for the production of substances like vitamin K and other metabolites in the large intestine. All of these substances are absorbed in the colon with water. The waste gets solidified into faecal matter in the rectum. The faecal matter leads to the initiation of a neural reflex that causes an urge. Defaecation is the egestion of feces through the anal opening. It is a voluntary process. It is carried out by a peristaltic movement.

Egestion Disorders

Egestion disorders can be of two types Constipation and Diarrhea. Constipation is the condition when the faeces harden due to delay in the time of evacuation and from the absorption of water. The bowel movement out of the anus can be difficult and strenuous. 

Whereas Diarrhea refers to a condition when the faeces material contains a lot of excess water and the movement of the faeces is liquid and frequent.

---

Excretion Process

[Click Here for Sample Questions]

Excretion is the removal of metabolic waste from the body. The waste comes out from excretory organs like lungs, kidneys and skin. The waste is produced from metabolic reactions.

• Lungs excrete air i.e. carbon dioxide and water vapour
• Kidneys excrete urine; urine consists of water, salts and urea. Urine formation consists of glomerular filtration, reabsorption, and secretion.
•  The filtration of blood carried out by glomerulus is called glomerular filtration. 
• Skin excretes heat and sweat.

To understand the process of Egestion in brief we need to focus on the digestion process.

---

Digestion Process

[Click Here for Sample Questions]

Egestion process is related to digestion process, for that it is important to digest the process from the beginning.

1. Ingestion- It is the first process; it is the process of taking or eating food into the mouth which is the initial digestive tract. In our mouth the food is being chewed by teeth, saliva mixes with it helping us to swallow it. The relevant organ is teeth and the relevant processes are swallowing and peristalsis. The opposite of ingestion is the egestion.
2. Digestion- It is the mechanical and chemical breakdown of food into small fragments of organic. Mechanical digestion means breakdown of large pieces of food into small pieces of food which can subsequently be accessed by digestive enzymes. And chemical digestion means the breakdown of food into small molecules. The relevant organs are mouth, teeth, alimentary canal, stomach and duodenum.
3. Absorption- the simple product of digestion is small enough to be absorbed by epithelial cells of the intestinal villi. Every day, the alimentary canal processes up to 10 liters of food, liquids but one liter or less than one liters of it enters into the large intestine. In undigested food the 90% of water absorbed in the small intestine .The entire small intestine is involved in the absorption of water and lipids. Bile salts and vitamin B12 are absorbed in the terminal ileum. The rate of absorbing monosaccharides at an estimated 120 grams per hour.
4. Assimilation- it is related to the movement of digested food molecules into the cells of the body. The liver plays an important role in the assimilation process. The best example is glucose is used in respiration to provide energy and amino acids which are used to build new proteins. The rate of the absorbed food i.e. glucose is for energy production, amino acids is for building up body materials and fats are used for energy reserve. The absorbed food material finally reaches and becomes a part of protoplasm called assimilation.
5. Egestion- the final process of the digestive system is Egestion. It happens when the feces pass out of the body through the anus. The feces are semisolid material.

Ingestion→ Digestion→ Absorption →Assimilation →Egestion

---

Things to Remember

1. Egestion is also called defecation
2. Defaecation is the egestion of feces through the anal opening.
3. Passing out of undigested food as feces or stool from the body is called Egestion.
4. Excretion is the removal of metabolic waste from the body.
5. Ingestion→ Digestion→ Absorption →Assimilation →Egestion

Also Read:

---