Chemical barriers

Chemical barriers are components of the immune system that use substances like acids, enzymes, and antimicrobial proteins to fight pathogens. For example, stomach acid destroys many bacteria that enter through food, while enzymes in tears and saliva break down and neutralize microbes on the skin and mucous membranes. These barriers act quickly, creating an inhospitable environment for germs, preventing infections before the body’s more specialized immune responses are triggered. They are an essential first line of defense, helping to protect the body from disease-causing organisms.