Library · Cellular process
Phagocytosis
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Phagocytosis comes from the Greek and means, roughly, cell that devours, which is exactly what it looks like under the microscope. The cell stretches its membrane out into false arms, the pseudopods, which surround whatever it is about to eat and pull it inside. It is two arms closing around something and dropping it into a bag that then seals shut.
Inside, what has been captured does not drift loose through the cell: it stays shut in a vesicle, a little sac called a phagosome. That sac goes on to meet a lysosome, the cell's store of digestive enzymes, the two fuse, and what is inside is broken down.
Not everything gets in this way. Phagocytosis is reserved for large things, bigger than half a micrometer, like a whole bacterium or the debris of a dead cell.
The immune system uses it all the time: macrophages clear away the remains of dead cells and capture bacteria that come tagged by opsonins, molecules that stick to the microbe and work as a label that says "eat me".
In brief
In phagocytosis, a cell's membrane extends pseudopods that engulf a particle and pull it inside.
Two arms closing around something and dropping it into a bag that then seals shut.
The particle ends up in a vesicle called a phagosome, which fuses with an enzyme-filled lysosome that breaks it down.
Only large particles enter this way, larger than half a micrometer, such as bacteria or cell debris.
The immune system uses it to clear debris and to capture opsonized bacteria.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhagocytosis, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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