What is an example of a chemical barrier in the human body?

Enzymes in saliva are a prime example of a chemical barrier in the human body. These enzymes, such as amylase, help initiate the digestion of carbohydrates and also play a crucial role in breaking down pathogens that enter the body through the mouth. By doing so, they help prevent infections and maintain the body's overall health.

Chemical barriers are typically substances that can neutralize or inhibit the growth of pathogens through chemical reactions. Salivary enzymes offer an immediate response to potentially harmful microorganisms, functioning as a first line of defense in the oral cavity before any immune response is activated. This highlights the importance of saliva not just in digestion but also in serving as a protective barrier to maintain oral and overall health.

The other factors listed, while essential to the body's defense, do not directly exemplify a chemical barrier in the same way. Skin proteins act as physical barriers, mucous membranes provide a combination of physical and chemical protections, and white blood cells are integral to the immune response rather than serving as a direct chemical barrier.