One of these antimicrobial proteins is lysozymes, which is an enzyme that digest the cell wall of the bacteria and destroys the microbes that try to enter the upper respiratory system and around the eyes. Mucus also traps the particals it comes into contact with. When the microbes are entering the upper respiratory system the get caught and either swallowed or expelled. The trachea is lined with special epithelial cells that are equipped with cilia that sweeps the out microbes and other particals that gets trapped by the mucus. Microbes that are present in food or caught in mucus from the upper respiratory system has to pass through the acidic gastric juices produced by the stomach lining.
Phagocytosis is the ingestion of invading particles by certain types of white blood cells.
This is the body main internal defense mechanism. Phagocytic cells are called neutrophils which comprise sixty to seventy percent of the white blood cells. These can destroy microbes by the chemical signals, neutrophils can leave the blood and enter infected tissue by amoeboid movement. The neurophils can only live a few days because they are self-destructive as well as destroying the foreign invaders. Another five percent of the white blood cells are made up of monocytes which provide phagocytic defense.