The immune system: how the body defends against disease

The immune system defends the body from pathogens like bacteria and viruses in layers. The first line of defense is barriers such as skin and mucus. If pathogens get past them, the innate response acts quickly and in the same general way against any invader, through inflammation and white blood cells that engulf microbes. The adaptive response is slower but targeted: B cells make antibodies that bind to a specific pathogen, T cells destroy infected cells, and memory cells left behind make the response to a later exposure much faster and stronger. Vaccines work by safely building that memory without causing the disease. The immune system depends on other systems, like the circulatory system, which carries white blood cells throughout the body.

This explanation is AI-generated and can occasionally be wrong. 🚩 Report