By respiratory system we usually mean the passages that transport incoming air to the lungs and to the microscopic air sacs called alveoli where gases are exchanged. The term respiration refers to the whole chain of processes from the inhalation of air to the use of oxygen in the cells. Index. Reference.
Phagocytes are the white blood cells that protect the body by eating (phagocytosing) dirt, bacteria and dead or dying cells. They are important for fighting infections. They are also important for becoming immune. Phagocytes are important in all animals and are very complex in vertebrates.
Phagocytosis is an effective nonspecific immune response. Phagocytosis recognizes alien cells and particles. For the phagocytosis to proceed, macrophages and neutrophils must first recognize the surface of a particle as foreign. When a phagocyte surface interacts with the surface of another body cell, the phagocyte becomes temporarily paralyzed.