Physical lines of defense include
1. Skin: The skin acts as a physical barrier to protect the body from harmful pathogens and microorganisms.
2. Mucous membranes: Mucous membranes line the digestive and respiratory tracts and provide a barrier that traps and expels harmful substances before they can enter the body.
3. Cilia: Cilia are tiny hair-like structures found in the respiratory tract that help to sweep away foreign particles and pathogens before they can infect the body.
4. Stomach acid: The acidic environment in the stomach helps to destroy harmful pathogens that are ingested with food and drink.
5. Tears and saliva: Tears and saliva contain enzymes that help to kill bacteria and neutralize harmful substances before they can enter the body.
6. Earwax: Earwax helps to trap and expel foreign particles before they can enter the ear canal and cause infection.
7. Cough reflex: The cough reflex helps to expel mucus and foreign particles from the respiratory tract to prevent infection.
8. Sneezing: Sneezing helps to expel irritants and pathogens from the nasal passages before they can cause infection.