How does the immune system work?

The immune system is a complex network of cells and proteins that defend the body against foreign invaders, such as bacteria, viruses, parasites, and cancer cells. The immune system works by recognizing and attacking these invaders while leaving the body's own healthy cells alone.

There are two main types of immunity: innate immunity and adaptive immunity. Innate immunity is the first line of defense and is composed of physical and chemical barriers, such as the skin and mucous membranes, that prevent pathogens from entering the body. If pathogens do enter the body, innate immunity responds quickly with a non-specific response, such as inflammation and the release of white blood cells to destroy the invaders.

Adaptive immunity is a more specific and targeted response that develops over time as the body is exposed to different pathogens. It involves the activation of T and B lymphocytes, which are specialized white blood cells that recognize and respond to specific pathogens. Once activated, these cells produce antibodies and memory cells that provide long-term protection against future infections.

The immune system is a complex and sophisticated defense mechanism that protects the body against a wide range of threats. However, it is not infallible, and sometimes it can overreact or underreact, leading to autoimmune diseases or increased susceptibility to infections.