Egestion refers to the process of elimination of undigested food and wastes from the body via the anus. The main function of excretion is to allow the body to get rid of waste products. This process of excretion takes place in the kidneys, bladder, and skin. Excretion is meant by the process of getting rid of waste products as well as toxins from the body. The major organs involved in the process of excretion are the kidneys, liver and lungs. The kidneys help in filtering the blood and in removal of waste products and toxins. The liver functions to break down toxins and removes them from the body. The lungs give out carbon dioxide and other toxins from the body. The removal of faeces from the alimentary canal is known as egestion or defecation. The faeces is referred to as the waste matter that is discharged from the alimentary canal.
Assimilation
Assimilation is referred to as the movement of digested food molecules inside the cells of the body where it can be further used. For example:
- In the process of respiration glucose can be used to provide energy.
- Amino acids are being used to build new proteins.
The liver plays a crucial role in the process of assimilation. For example, it helps in the conversion of glucose into glycogen (it is a complex carbohydrate that is used for storage) and amino acids into proteins. The liver is also involved in the process of deamination. That is the removal of the nitrogen-containing part of amino acids, to form urea, further with the release of energy from the remaining of the amino acid.
Egestion
The small intestine functions to absorb the majority of the water present in the contents of the gut. By the time this content reaches the end of the small intestine, most of the digested food is also absorbed. The remaining material comprises:
- Water
- Bacteria (living and dead)
- Cells situated in the inner lining of the gut
- Indigestible substances – like those of cellulose present in plant cell walls
The colon represents the first part of the large intestine. It helps in the absorption of all of the remaining water. Thus leaving behind semi-solid waste material known as faeces. The faeces are temporarily stored in the rectum, which is the last region of the large intestine. Egestion occurs when these faeces pass out of the body via the anus.
Digestion in case of protozoan organisms like those of amoebas and paramecium takes place when a food particle is taken up by the food vacuole. The vacuole and a lysosome unite together, thereby resulting in the formation of a digestive vacuole, and the products of digestion are absorbed by the vacuolar membrane. Indigestible wastes are generally expelled.
Importance of egestion
Egestion is a crucial process in humans and animals since it is the only means of disposal of the undigested food from the system. If bowel movement is knowingly delayed for longer periods, then it may lead to a megacolon and may eventually lead to bowel rupture.
Conclusion
For unicellular organisms, the undigested food is transported up to the cell membrane and then released outside of the body. Various multicellular animals do not possess a specialised digestive system. As it can be seen, in hydra, the food gets digested in the stomach sac, and the food is egested out through the mouth. With this we come to an end of this topic. We hope you were able to clear all your concepts regarding egestion in humans.