Intracellular digestion

Intracellular digestion can also refer to the process in which animals that lack a digestive tract bring food items into the cell for the purposes of digestion for nutritional needs. This kind of intracellular digestion occurs in many unicellular protozoans, in Pycnogonida, in some molluscs, Cnidaria and Porifera. There is another type of digestion, called extracellular digestion. In amphioxus, digestion is both extracellular and intracellular.

Function

Intracellular digestion is divided into heterophagic digestion and autophagic digestion. These two types take place in the lysosome and they both have very specific functions. Heterophagic intracellular digestion has an important job which is to break down all molecules that are brought into a cell by endocytosis. The degraded molecules need to be delivered to the cytoplasm; however, this will not be possible if the molecules are not hydrolyzed in the lysosome. Autophagic intracellular digestion is processed in the cell, which means it digests the internal molecules.