The Phagocytosis Is the process by which certain cells called phagocytes ingest or swallow other cells or particles. The phagocyte can be a single-celled organism, such as an amoeba or one of the body's cells.
In some animal life forms, such as amoebae and sponges, phagocytosis is a feeding medium. In higher animals phagocytosis is primarily a defensive reaction against infection and invasion of the body by foreign substances (antigens).
Simply put, phagocytosis in the human body translates as the time to eat the cells, which like any living organism need to eat and drink. Phagocytosis is the process of a cell that eats. That is, it is a type of endocytosis.
Endocytosis occurs when a cell leaves and takes something. Phagocytosis is this same situation, but when a solid is obtained.
The classic example is an amoeba eating a bacteria. First, the cell detects the bacteria because of the chemicals in the environment. The cell then moves to the prey.
Once contact is made, the amoeba slowly wraps its cell membrane around the object. When the membranes extend towards the dam, they are called pseudopodium. When the cell membrane surrounds the object, the object has been sealed in a new vesicle.
The final step is the digestion of the prey. If a cell does not act quickly, the bacteria could begin to reproduce. Lysosomes quickly attach to the food vesicle and release digestive enzymes.
The enzymatic action is called an oxidative explosion. The food breaks down and the amoeba absorbs the nutrients. Residual particles remain in the gallbladder and can be sent out of the cell.
Phagocytosis and the Immune System
Phagocytosis / Photo retrieved from fagositosis77.blogspot.com
Phagocytosis is a critical part of the immune system. Several types of cells of the immune system perform phagocytosis, such as neutrophils, macrophages, dendritic cells and B lymphocytes.
The act of phagocytizing the pathogenic or foreign particles allows the cells of the immune system to know what they are fighting against. By knowing the enemy, cells of the immune system can target specific particles that circulate in the body.
Another function of phagocytosis in the immune system is to ingest and destroy pathogens (such as viruses and bacteria) and infected cells. By destroying infected cells, the immune system limits how quickly the infection can spread and multiply.
Cells of the immune system performing phagocytosis may also use many mechanisms to destroy pathogens, such as:
Radicals of oxygen: Are highly reactive molecules that react with proteins, lipids and other biological molecules. During physiological stress, the amount of oxygen radicals in a cell can increase drastically, causing oxidative stress, which can destroy cellular structures.
Nitric oxide: Is a reactive substance, similar to oxygen radicals, that reacts with superoxide to create other molecules that damage several biological molecules.
Antimicrobial Proteins: Are proteins that specifically damage or kill bacteria. Examples of antimicrobial proteins include proteases, which kill several bacteria by destroying essential proteins, and lysozyme, which attacks the cell walls of gram positive bacteria.
Antimicrobial peptides: The antimicrobial peptides are similar to the antimicrobial proteins in which they attack and kill the bacteria. Some antimicrobial peptides, such as defensins, attack bacterial cell membranes.
Proteins of Union: Binding proteins are often important players in the innate immune system because they competitively bind to proteins or ions that would otherwise have been beneficial to bacteria or viral replication.
Lactoferrin, a binding protein found in mucous membranes, binds to iron ions, which are necessary for the growth of bacteria.
Some species of amoebae, algae and other unicellular organisms are known to use endocytosis and phagocytosis to eat.
The mechanisms of engagement of phagocytosis and endocytosis allow the larger species to consume smaller species easily.
How does phagocytosis occur?
The cells have to complete some steps in order to phagocyte something. In order to illustrate this a little easier, let's say we are following a macrophage (a type of immune cell) by phagocyting a virus.
It should be noted, however, that many different types of cells perform phagocytosis. It is important to emphasize that the virus and the cell need to come into contact with each other.
Sometimes the immune cell accidentally collides with a virus in the bloodstream. Other times, the cells move through a process called"chemotaxis, which Is the movement of an organism or cell in response to a chemical stimulus.
Once the macrophage swallows a virus (1-3), it breaks it up into pieces with lysosome enzymes (4,5) that are then released from the cell as harmless waste (6). Photo retrieved from: askabiologist.asu.edu.
Many immune cells move in response to cytokines, small proteins used specifically for cell signaling. Cytokines indicate that the cells move to a certain area of the body where the particles are (in this case, a virus).
Phagocytosis is a process in which a cell joins the element it wants to gobble on its surface and pulls the element inwardly as it wraps around it.
The process of phagocytosis often happens when the cell is trying to destroy something, such as a virus or an infected cell, and is often used by cells of the immune system.
Phagocytosis differs from other endocytosis methods because it is very specific and depends on the cell being able to bind to the element it wants to gobble through the cell surface receptors.
Phagocytosis will not occur unless the cell is in physical contact with the particle it wants to swallow.
References
- Ellen, M. (2013). "Phagocytosis: Definition, Process & Types". Retrieved from study.com.
- British Encyclopedia publisher team. (2017). "Phagocytosis". Retrieved from britannica.com.
- Editor team of KHAN Academy. (2017). "Phagocytosis". Retrieved from khanacademy.org.
- Team editor of Biology-online. (2008). "Phagocytosis". Retrieved from biology-online.org.
- Rader, A. (2017). "Phagocytosis - Time to Eat!". Retrieved from biology4kids.com.
- Team editor of Human Pathology. (2004). "Phagocytosis". Retrieved from humpath.com.
- Team Editor of Courses Washington. (2017). "Phagocytosis". Retrieved from /courses.washington.edu.