ANATOMY

Detailed explanation-1: -The skin, mucous membranes, and endothelia throughout the body serve as physical barriers that prevent microbes from reaching potential sites of infection.

Detailed explanation-2: -Mucus not only provides a physical barrier, it also contains chemicals that help protect us from pathogens. Epithelial cells also secrete chemicals that prevent infection. This is true of epithelial cells on our skin and in our digestive, respiratory, and genital tracts.

Detailed explanation-3: -The innate immune system includes physical and anatomical barriers as well as effector cells, antimicrobial peptides, soluble mediators, and cell receptors (Table 1).

Detailed explanation-4: -The closed surface of the skin and of all mucous membranes already forms a physical barrier against germs, which protects them from entering. Additionally, chemical substances like acid, enzymes or mucus prevent bacteria and viruses from gaining a foothold.