Egestion meaning

The human digestive system is composed of a long muscular tube and many other accessory organs like those of the salivary glands, pancreas and gallbladder. All these glands are responsible for food ingestion, digestion, absorption of digestion products and then the elimination of undigested materials. Egestion explains the act or process of discharging the undigested food as faeces. To egest refers to discharge of undigested material or food.

Egestion

It refers to the removal of undigested food materials upon reaching the end of the small intestine, all the digested food products, along with the minerals and vitamins plays a very significant role in the body, these must have been removed from the watery contents. The remaining matter comprises the indigestible components of food like that of cellulose obtained from the consumption of plant-based foods. These materials are further passed on to the large intestine. The 4 major functions of the large intestine are:

• Maintaining water and electrolytes balance (i.e. sodium, chloride) from indigestible food matter
• Formation and storage of faeces
• Fermentation of some of the indigestible food matter via bacteria
• Maintaining a bacterial population.

It has been observed that there are around 500 species of bacteria present in the large intestine, and these are generally friendly (commensal) bacteria, they perform a variety of functions. For example, undigested carbohydrates (such as fibre) gets metabolised to short-chain fatty acids, and also to small amounts of vitamins, mainly vitamin K and the vitamin B group, are formed for its absorption into the blood.

Once the undigested material gets accumulated in the rectum, it functions to stimulate a response that results in the evacuation of the waste through the anus.

Ingestion

It refers to the process of taking in the food. Food is taken into the mouth where it gets physically broken down by the teeth into smaller pieces. The presence of food in the mouth activates a nervous reflex that leads the salivary glands to release a watery fluid known as saliva into the mouth. Saliva functions to moistens and lubricates the food, with the help of a slippery substance known as the  mucin, it makes swallowing of the food easier and also functions to dissolve some of the food and allow it to be tasted. Further with the help of a digestive enzyme, called as amylase, in saliva helps in chemical digestion of starch to begin.

Egestion vs Ingestion

Ingestion and egestion are generally two basic events that occurs during the feeding of animals and protozoa. The main point of difference between ingestion and egestion is that ingestion is normally the intake of food into the body while egestion is the elimination of waste products out of the body. Ingestion takes place through the mouth in animals. Whereas in protozoa, ingestion occurs via endocytosis. After the entry of the food into the digestive system of animals, mechanical digestion and chemical digestion takes place to break down the food particles into smaller constituents that are easily absorbed by the body. Protozoa carries the food in a vesicle and digests it inside the vesicle due to the presence of digestive enzymes. The removal of wastes of the digestion takes place through the anus in animals. In protozoa, the egestion occurs via the exocytosis.

Conclusion

Both ingestion and egestion are two important events of the feeding of humans.

Both ingestion and egestion functions to take in the nutrients into the body and further leads to the elimination of unwanted materials from the body. Ingestion and egestion are the first and last steps of the feeding of humans and protozoa. Ingestion refers to the intake of food into the body while egestion represents the elimination of the undigested materials from the body.