The word exocytosis itself says 'exo' meaning out and 'cyto' meaning cell. In layman's terms, we can say that exocytosis is the discharge of materials like waste products, protein, hormones, etc., out of the cell. It can also be called the process of excretion of macrophage or very big particles out of the cell, which cannot be excreted through the cellular membrane. Exactly opposite to this process, is endocytosis which involves the intake of substances inside the cellular body. If we look for a proper exocytosis definition, it will state as:
"Exocytosis is the secretion of macrophage through the plasma membrane by the diffusion of vesicles."
Steps Involved in Exocytosis
In the process of exocytosis the vessels which are to be excreted out of the cell are taken to the cell membrane and then the vessels get fused with the plasma membrane and the material inside it is secreted out of the cell. This entire process can be divided into five steps.
In the first step, the waste product or the material which is to be excreted is taken by the vesicle through the cytoplasm towards the cell membrane.
Once the vesicle reaches the cell membrane, it is pulled by the cell which will carry on the further process of excretion.
As soon as the vesicle comes in contact with the cell membrane, chemical reactions take place. Due to these chemical reactions, the vesicle merges with the protein of the cell membrane.
In this step, the vesicle as well as the cell membrane prepare themselves for the last step which is associated with the release of the substances.
This is the last step of the exocytosis. In this step, the wall of the vesicle and the cell membrane fuse together and push the content of the vesicle out of the cell. This can also be considered as the reason behind the increasing size of the plasma membrane.
Functions of Exocytosis
Some of the functions of exocytosis in cell biology are as follows.
- If the cells are associated with the neurons then they are involved in the release of neurotransmitters.
- By the process of exocytosis, the cells communicate with each other about the defense measures to be taken at the time of diseases.
- They release or expel the waste material from the cell.
- They are also responsible for the release of glucose, enzyme, protein, hormones, etc.