MICROANATOMY

Detailed explanation-1: -Skin, tears and mucus are part of the first line of defence in fighting infection. They help to protect us against invading pathogens.

Detailed explanation-2: -Epithelial tissues cover most of the external and internal surfaces of the body and its organs. Inevitably, these tissues serve as first line of defence against inorganic, organic, and microbial intruders. Epithelial cells are the main cell type of these tissues.

Detailed explanation-3: -The first line of defense against infection are the surface barriers that prevent the entry of pathogens into the body. The second line of defense are the non-specific phagocytes and other internal mechanisms that comprise innate immunity.