How humans are protected from infection: the immune system
The immune system is a flexible protection system that protects the human body against invasion by microorganisms. It is not foolproof and many pathogens can overcome the immune defences and cause disease. The immune defence system is broadly divided into the non-specific (innate or natural) system and the specific (adaptive) immune system. If either system is compromised because of poor health, a poor vascular supply, poor nutrition, and so on, then an individual will be more prone to contracting infection or being colonized by microorganisms.
The immune system protects people from infection and is broadly divided into two parts: the non-specific and the specific immune system. The non-specific system includes numerous physical mechanisms, such as the inflammation reaction, cough reflex, and skin structure, and physiological factors, enzymes, complement, lactofer- rin, mucous, macrophages, and cytokines. The specific system is focused on the production of protective antibodies.