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Phagocytosis: bacterial stages


Phagocytosis it is a process that leads us to look closely at cells, those that we can only imagine while experts describe them to us in a more or less scientific way according to the notions of science we have. Let's see what phagocytosis is for and how it happens, too in our body, without our knowledge, or almost.

Phagocytosis: meaning

It is defined as the method of issue of the secretion from a cell, in chemistry, more generally in the scientific field with this term we want to indicate the ability that in many cases the cells show to know and be able to ingest foreign materials and to destroy them. "External materials " is a deliberately vague term because phagocytosis concerns various types of substance that they can be "incorporated".

In general the cells of animals show a phagocytic activity and they are divided according to how it happens. We find professional and optional phagocytes. In the first category we find neutrophils, eosinophils and monocytes / macrophages and in this case phagocytosis is one prominent activity, in the other case, the one in which they exist mast cells, endotheliocytes and other cells, it is an activity not at the center of their existence but at most marginal.

Phagocytosis: stages

Phagocytosis occurs in stages, the first being the exocytosis which consists in transporting large quantities of materials out of one's cytoplasm. In this first part of the process the cells release the secretion in small quantities and gradually accumulates all the secret until the arrival of a signal indicating when to throw everything out. In conjunction with theexocytosis we always observe the endocytosis process which we can imagine as its exact inverse.

To perform this activity is a vesicular corpus called endosome, this phase is important to recover the surface of the membrane, that quantity that was lost during exocytosis, and to bring inside the cell together with the membrane, substances that were previously outside.

This "Incorporate" the material found outside the cells, can take place with two main methods of internalization: non-specific and specific. In the first case, the intake of extracellular fluids occurs without any passage for its recognition by the membrane, therefore substantially without "Selection at the entrance".

In the case inspecific internalization, on the other hand, there is the presence of a receptor that becomes the mediator of the process and causes only some specific extracellular molecules. Obviously it depends on the cell in question, for different cells there are different membrane receptors so that each type is able to internalize different molecules, the ones you need.

Bacterial phagocytosis

One of the types of material that is most often internalized from the cells with the process of phagocytosis is bacterial but there are cases where it is a fragment of food, for example. The fact is that there is a cell that "eats" a something big that is outside and that, to do so, it must emit cytoplasmic expansions bounded by a membrane. To learn more about the world of bacteria, there is an article dedicated to gram positive and negative bacteria

There is a curious variant of phagocytosis, called autophagocytosis, and we can imagine what it is. In this case it is the first-person cell that he decides to degrade his organelles to renew them. It is the lysosomes that carry out this step in animal cells and that leads to the formation of a large vesicle called an autophagosome, then expelled by exocytosis.

Phagocytosis and white blood cells

In animals, including humans, there are cells specialized in phagocytosis and which can therefore incorporate and digest bacteria and other foreign particles. Thanks to this function, they play a leading role in immune system and against white blood cells. They are called phagocytes, in a fairly generic way, and in this category we find the macrophages (derived from monocytes) and i microfagi (neutrophilic leukocytes).

Phagocytosis and brain

The phagocytosis process also occurs in the brain: the cells called microglia are those in charge of cleaning. Precisely this passage was the subject of studies in the Neuroscience Center of the University of the Basque Country where we wanted to investigate what happens in particular in people suffering from epilepsy.

In general, what happens, when neurons die, is that with phagocytosis their "remains" are expelled so that the brain cleansing. But in people with neuro-degenerative diseases, something gets stuck.

Published in 2016, the study related to phagocytosis in patients with epilepsy, shows how neurons that die during an epilepsy attack cannot be expelled by phagocytosis in a sick brain. This is because during an epilepsy attack the cells in charge, the microglia, go haywire and they do not do their job.

If dead neurons stay where they are accumulating, the damage spreads to neighboring neurons which die in chain making the situation worse. This discovery has opened up new horizons of treatment, not only for the epilepsy for which they could be found new drug therapies, but also more generally for the treatment of other degenerative brain pathologies.

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Video: Inflammation (September 2021).