Why are physical defenses called the body's first line of defence against disease?

Physical defenses are considered the body's first line of defense against disease because they provide immediate protection against pathogens. These barriers, such as the skin, mucous membranes, and cilia, prevent the entry of harmful microorganisms into the body. They act as a physical shield, blocking pathogens and reducing the likelihood of infection. Additionally, these defenses are always present and ready to respond, making them crucial for maintaining overall health.