Question

The first stage of phagocytosis is attracting phagocytes to the site of infection, which is known as

Answer 1

Step 1: Activation

Infection of a given site in the body stimulates the delivery of neutrophils to the site through chemotaxis. Here, such attractants as tissue debris and bacteria product activate the movement of the phagocytic cells to move to the infected site.

Step 2: Adherence/binding

Bacteria with such molecules/ substances as IgG or C3b are easily identified by the phagocytes. Here, such receptors as opsonin receptors on the plasma membrane of the phagocyte bind to these molecules allowing for the bacteria to be identified and ultimately ingested.

Step 3: Ingestion/Engulfment

Attachment/binding allows for identification and ingestion of the bacteria. During ingestion, the cell membrane of the phagocyte invaginates while surrounding the bacteria and engulfs it. This process results in the bacteria being enclosed in a vesicle/phagosome within the phagocyte

Step 4: Enzyme action

Within the phagocyte (cell) the vesicle containing the invading bacteria comes in contact with the lysosomal granules to form a phagolysosome (digestive vacuole). Here, lysosomal activity helps destroy and kill the bacteria.

Answer;

Macrophages, neutrophils, and dendritic cells are the major phagocytes of the immune system.

A neutrophil is a phagocytic cell that is attracted via chemotaxis from the bloodstream to infected tissues. These spherical cells are granulocytes.

The first stage of phagocytosis is attracting phagocytes to the site of infection is known as immune response.