What is the body's first and second line of defence?

The body's first line of defense consists of physical and chemical barriers that prevent pathogens from entering, such as the skin, mucous membranes, and secretions like saliva and stomach acid. The second line of defense involves the innate immune response, which includes white blood cells, inflammation, and the activation of proteins that help fight infections. Together, these defenses provide a robust response to protect the body from harmful invaders.