How does the skin function as a barrier to infection?

The skin serves as a crucial barrier to infection primarily by providing a physical barrier and secreting antimicrobial substances. Its outer layer, the epidermis, is composed of tightly packed cells that create a formidable defense against microorganisms. This physical barrier is important for preventing pathogens from entering the body.

In addition to the physical barrier, the skin has glands that produce various antimicrobial substances, such as defensins, which are peptides that disrupt the membranes of pathogens, and lysozyme, which breaks down the cell walls of bacteria. Sebum produced by sebaceous glands also has antibacterial properties and helps to maintain skin integrity.

The combination of these features enables the skin to effectively reduce the risk of infections from pathogens that may come into contact with the surface. This understanding highlights the skin's role not just as a passive barrier but as an active participant in the immune defense system.