If the following are placed in the order of occurrence, which would be the third step?
a. diapedesis
b. digestion
c. formation of a phagosome
d. formation of a phagolysosome
e. margination

Verified step by step guidance

1. Understand the process of phagocytosis and the immune response.
2. Identify the sequence of events in phagocytosis: margination, diapedesis, phagosome formation, phagolysosome formation, and digestion.
3. Recognize that margination is the first step where white blood cells move to the blood vessel walls.
4. Acknowledge that diapedesis is the second step where white blood cells exit the blood vessels.
5. Determine that the formation of a phagosome is the third step, where the cell engulfs the pathogen.

Key Concepts

Diapedesis

Diapedesis is the process by which white blood cells move out of the bloodstream and into tissues. This occurs during an immune response, allowing immune cells to reach sites of infection or injury. It is a crucial step in the inflammatory response, enabling the body to combat pathogens effectively.

Phagocytosis

Phagocytosis is the process by which certain cells, such as macrophages and neutrophils, engulf and digest pathogens or debris. This involves the formation of a phagosome, which is a vesicle that contains the ingested material. The phagosome then fuses with a lysosome to form a phagolysosome, where the material is broken down.

Phagolysosome Formation

The formation of a phagolysosome is a critical step in the immune response, occurring after a phagosome engulfs a pathogen. This vesicle then merges with a lysosome, which contains digestive enzymes, allowing for the breakdown of the engulfed material. This process is essential for the elimination of pathogens and the resolution of infection.