Chemical barriers also protect against infection. The skin and respiratory tract secrete antimicrobial peptides such as the β-defensins. Enzymes such as lysozyme and phospholipase A2 in saliva, tears, and breast milk are also antibacterials. Vaginal secretions serve as a chemical barrier following menarche, when they become slightly acidic, while semen contains defensins and zinc to kill pathogens. In the stomach, gastric acid and proteases serve as powerful chemical defenses against ingested pathogens.
What are the anitmicrobial peptides secreted by the skin called? What enzymes in saliva are antibacterial in nature? Semen contains what in order to kill pathogens? What compounds in the stomach protect against ingested pathogens? Vaginal secretions serve as a chemical protective barrier following what?