IMMUNOLOGY

Detailed explanation-1: -The epidermis functions as a physical barrier to the external environment and works to prevent loss of water from the skin.

Detailed explanation-2: -The lipid matrix in the outermost layer of the skin is crucial for the skin barrier function: cholesterol, free fatty acids and ceramides are important components of this lipid matrix.

Detailed explanation-3: -The skin provides an effective barrier between the organism and the environment, preventing the invasion of pathogens and fending off chemical and physical assaults, as well as the unregulated loss of water and solutes.