Phagocytosis Revision notes | A-Level Biology AQA

Phagocytosis

This lesson covers:

The role of phagocytes in the immune response
The process of phagocytosis

Phagocytes

Phagocytosis is a type of non-specific defence involving a type of cell known as a phagocyte.

Phagocytes are a type of white blood cell that engulf and destroy pathogens (phagocytosis). They are found in the blood and body tissues of many organisms.

Phagocytosis

The process of phagocytosis is carried out as follows:

The pathogen releases chemicals that attract a phagocyte.

Diagram illustrating the process of phagocytosis showing a phagocyte and a pathogen.

The phagocyte recognises the pathogen's antigens as non-self. This causes the phagocyte to bind to the pathogen.

Diagram showing the process of phagocytosis involving a phagocyte and a pathogen.

The phagocyte engulfs the pathogen.

Illustration showing a phagosome containing a pathogen inside a phagocyte.

The pathogen is now contained within a vacuole known as a 'phagosome'.

Diagram showing the process of phagocytosis with a phagolysosome and lysosome.

The lysosome, containing lysozymes, fuses with the phagosome to form a phagolysosome.

Diagram showing a phagocyte with a pathogen inside.

Lysozymes digest and destroy the pathogen.

The phagocyte presents the pathogen's antigens on its surface to activate other cells in the immune system. The phagocyte is then referred to as an antigen-presenting cell (APC).

All stages of phagocytosis.

The diagrams above only show one phagocyte and one pathogen, but in reality many phagocytes and many pathogens interact at the same time.