Phagocytosis is a process that occurs when a cell attempts to kill foreign particles or pathogens such as bacteria or an infected cell by enveloping them in lytic enzymes, which is a process known as phagocytosis. In addition to single-celled creatures such as amoebas, this process is observed during the digestion of food particles by bacteria.
Pathogens such as viruses, bacteria, and other infected/dead cells are ingested by phagocytes cells in humans, which defend the body by ingesting them. In truth, phagocytosis is a critical component of the immune system, and it is carried out by specific cells such as neutrophils and macrophages. The immune system prevents the spread of illness or diseases in the body by killing the germs that cause them.
Phagocytosis: A brief introduction
Phagocytosis is the process by which certain live cells known as phagocytes use their plasma membrane to devour or engulf other big cells or particles (greater than 0.5 microns in size), resulting in the formation of an interior chamber known as the phagosome. It is a type of endocytosis with a few differences. Phagocytic cells are referred to as phagocytes because they carry out phagocytosis. It is known as frustrated phagocytosis when a phagocytic cell exposed to an opsonized surface extends itself out in an attempt to swallow the surface in which it has been exposed to.
It is possible for the phagocytic cell to be any of the body’s cells, such as a phagocytic white blood cell, or it might be a single-celled creature, such as an amoeba. While phagocytosis in amoebas and certain other primate life classes, such as sponges, is referred to as the feeding mechanism, in other life classes, such as bacteria, it is referred to as the feeding mechanism. Furthermore, in certain higher primates, phagocytosis serves primarily as a preventative response to germ and body invasion by foreign substances (antigens). Because epithelial and endothelial cells are examples of non-phagocytic cells, epithelial and endothelial cells are not used for this purpose.
Types of Phagocytosis
Macrophages
Phospho Phagocytosis by macrophages is a kind of phagocytosis that is derived from monocytes and is detected in tissues. When it comes to the phagocytosis of cellular wastes, bacteria, and various external objects, macrophage phagocytosis plays a crucial role as a primary defence mechanism for the body.
Monocytes
Monocytes are a type of phagocytic cell that can be found in the bloodstream and are responsible for phagocytosis. They circulate throughout the body, and if the tissue is infected, it is possible that they will leave the bloodstream and infiltrate it.
Dendritic Cells
Dendritic cells’ primary function is to serve as a link between the adaptive immune system and the innate immune system, which they accomplish through attachment. As immature dendritic cells travel through the circulation and tissues, they continuously sample the pathogens they encounter (through phagocytic white blood cells, which are responsible for the sampling) through the process known as macropinocytosis.
Granulocytes
Pneumocyte cells such as eosinophils, basophils, and neutrophils are composed of a group of phagocytes with dense granules in their cytoplasm, which are known as granulocytes.
Process of Phagocytosis
Living cells take in a wide variety of chemicals in order to impede the function of their cell membrane. The majority of these molecules or materials are fluids, ions, and oxygen, although others are easily transported over the membrane by mechanisms such as osmosis and ion pumps, which are both described below.
Some items, such as viruses and other particles, may be too large to be passed through the sheath using such mechanisms, resulting in failure. This explains why the cell produces so much matter/objects that it can engulf within the cell.
This process entails the introversion of the cell membrane, which permits the cell to transport the particle into the body of the cell. It is possible to categorise endocytosis into three types, depending on the cell and methodology used to immerse the particles. The first two are known as pinocytosis and phagocytosis, while the third is known as receptor-mediated endocytosis.
What distinguishes phagocytosis from pinocytosis is the presence of unique surface proteins on the surface of phagocytes, which enable them to recognise and attach to settling particles before consuming them completely. This type of endocytosis is dependent on the junction that connects the cell with the thing that it is trying to reach.
Steps of Phagocytosis
Phagocytosis is comprised of four steps, which are as follows:
Step 1: Actuation or activation
This stage of phagocytosis takes place when the cell grows in close proximity to the things that have been offered. For example, when phagocytes are in close proximity to bacteria, the phagocytes are stimulated and the binding process is accelerated.
Step 2: Coupling or binding
During this step, the phagocyte’s covering receptors stick to the object’s covering, which is called adhesion. This phase is necessary in order for the particle to be absorbed.
According to the cell, different types of cover receptors play a key part in phagocytosis (binding) and have different effects.
Step 3: Ingestion
As soon as the phagocyte encircles the particle, it begins to open up. Phagocytosis is a process that involves the ingestion of particles and the formation of a vesicle or vacuole around the particle as the particle is swallowed completely.
Step 4: Conversion or digestion
In some cells, enzymes in the lysosome, which resembles a vesicle, break down the particle into its constituent parts. Exocytosis is the process by which excess components that are unable to be used are removed from the cell. Peroxisomes, which are specific formations that are created in phagocytes that are essential for vaccination, are formed to confine and eliminate hazardous particles in the body.
Conclusion
In the 1860s, a pathologist named Kranid Slavjansky published a paper in which he documented the presence of foreign pieces within cells. Later, in the 1880s, a Russian-born microbiologist and naturalist named Élie Metchnikoff used the term phagocyte to describe the process by which immune cells ingest and kill foreign things such as bacteria. Aspects of his research included the discovery that phagocytic cells play an important role in the immune response and the observation of the phenomenon of frustrated phagocytosis. This finding even earned him the Nobel Prize in Physiology in 1908 for his efforts.