Pathogens can enter the body through the respiratory system. Pathogens that cause influenza, tuberculosis and bronchitis infect in this way. However the respiratory system has defenses to trap these pathogens and expels them. The first is mucus in the throat, this is a thick gooey like substance produced by the goblet cell, it is there to catch up the pathogens and it can be coughed up. Another defence are the microscopic hairs in the trachea, these are called cilia and are there to stop pathogens being taken into the body, so they get trapped and can be expelled by the mucus.