Outline the process of phagocytosis by macrophages.

Initially, the bacteria/pathogen will bind to a receptor located on the surface membrane of the macrophage. Pseudopodia will form around the bacteria, resulting in the macrophage surrounding the bacteria/pathogen. The membrane of the pseudopodia will then fuse and will form a phagocytic vacuole - the bacteria/pathogen is enclosed within the phagocytic vacuole. Via lysosome action, lysosomes will fuse to the surface of the phagocytic vacuole and will relate digestive enzymes, such as lysozyme, which will destroy the bacteria/pathogen. The macrophage will then present the bacteria/pathogen's antigens via MHC (major histocompatibility complex) on the cell surface membrane. This result in the formation of an APC (antigen presenting cell), which will activate other immune system cells.