Phagocytosis

Engulfing and destruction of invaders. it rids the body of debris after tissue injury.

• 7 Steps:
• Exposure/invasion
• Attraction
• Adherence
• Recognition
• Cellular ingestion
• Phagosome formation
• Degradation

Phagocytosis is triggered by injury or invasion or exposure, the first step of phagocytosis.

WBC Comes in contact with target ( antigen, invader or foreign protein).

Chemotaxins: substances that attract neutrophils and macrophages. They come from damaged tissues and blood vessels.

phagocytic cell must bind to target.

Opsonins - increase contact by coating the target cell. ex. dead neutrophils, antibodies and activated (fixated) complement components. The process is called complement activation and fixation as part of the opsonization.

Inactive complement proteins in the blood are stimulated and becomes active. it joins other activated complement proteins, surrounds an antigen and sticks to the antigen.

The leukocytes checks the HLAs to see if it is a self or non self cell.

The target cell is engulfed inside and form a vacuole.

Occurs when the phagocyte's granules are inside the vacuole. These granules break and release enzymes that attack the ingested target.

Enzymes inside the phagosome digest the target. It breaks into small particles.