Energy is necessary for each and every organism in a body to remain active. However to gain energy from the outer environment cells does not only require to retrieve molecule but also need to break them apart. This basic process is called as intracellular digestion. In its broadest sense,intracellular digestion means the breaking down of the substances within the cytoplasm of a cell. In detail, a phagocyte’s duty is gaining food particles and digesting it in a vacuole. For example, following phagocytosis, the ingested particle (or phagosome) fuses with a lysosome containing hydrolytic enzymes to form a phagolysosom; the pathogens or food particles within the phagosome are then digested by the lysosome’s enzymes.
Intracellular digestion can also defined as the process in which animals that lack a digestive tract bring food items into the cell due to the reason of digestion for nutritional needs. Then there comes another kind of digestion, known as extracellular digestion. In amphioxus, digestion is both extracellular and intracellular.
The process of intracellular digestion is divided into two groups the heterophagic digestion and autophagic digestion. These two kinds of intracellular digestion occur in the lysosome and they both have very specific functions. The Heterophagic intracellular digestion has an important fnction which is breaking down all molecules that are brought into a cell by endocytosis. The degraded molecules require to be delivered to the cytoplasm; however, this cannot be possible if the molecules are not hydrolysed in the lysosome. Autophagic intracellular digestion occurs in the cell, which means it helps in the digestion the internal molecules.
Extracellular DigestionIt is a phenomena in which saprobionts provides by secreting enzymes via cell membrane onto the food. The enzymes catalyse the digestion of the food into molecules small enough to be carried up by passive diffusion, transport or phagocytosis. This process is known as extracellular because the process is carried out of the cell. It may take place in the lumen of the digestive system, in a gastric cavity or other digestive organ, or completely outside the body.
The meaning if the word extra is outside, which defines that extracellular digestion, must take place outside the cell. In this kind of digestion food is broken down outside the cell with the help of mechanically or with the help of acid by special molecules called enzymes.
Fungi and other decomposers performs extra cellular digestion .They suck the life out of their host by releasing chemicals which breakdown the food they are living on . Once broken down their cells absorbs the nutrients released.
Difference between Intracellular and Extracellular digestion
- The process of Intracellular digestion takes place inside the cell while on the other hand the process of Extracellular digestion takes place outside the cell in the cavity of the alimentary canal.
- Intracellular digestion involves secretion of digestive enzymes by the surrounding cytoplasm into the food vacuoles while on the other hand Extracellular involves secretion of digestive enzymes by special cells into the cavity of alimentary canal by duds.
- The process of Intracellular digestion takes place in unicellular organisms and in few other lower organisms. While on the other hand Extracellular digestion takes place in multicellular organisms.