Both exogenous and endogenous substance can act as chemoattractants. Bacterial products are an example of an exogenous chemoattractant. The increase in intracellular calcium triggers the assembly of contractile elements responsible for cell movement. Leukocytes move by extending a pseudopod which pull the rest of the cell in the direction of the extension. The pseudopod contains the proteins actin and myosin, as in muscle.
Motion involves rapid assembly, contraction and disassembly of a contractile apparatus by the cells.
Phagocytosis Phagocytosis and the release of enzymes by neutrophils and macrophages are two of the major benefits of the inflammatory process. Engulfment Binding of an opsonised particle to its receptor is sufficient stimulus to trigger engulfment. During engulfment extensions of the cytoplasm flow around the object to be engulfed eventually resulting in complete enclosure of the particle within a phagosome. Killing or degradation Bacterial killing is accomplished largely by oxygen dependent mechanisms. Phagocytosis stimulates a burst in oxygen consumption, glycogenolysis, increased glucose oxidation via the hexose-monophosphate shunt and production of reactive metabolites.