What serves as a line of protection against pathogens entering the body?

The body's first line of protection against pathogens includes physical barriers like the skin and mucous membranes, which act as a shield to prevent the entry of harmful microorganisms. Additionally, secretions such as saliva, tears, and mucus contain enzymes and antimicrobial substances that help neutralize potential threats. These defenses work together to create an initial line of defense, reducing the risk of infection.