en.wikipedia.org
Immune system
Biological system protecting an organism against disease
- The immune system is a network of biological systems that protects an organism from diseases.
- It detects and responds to a wide variety of pathogens, such as viruses, bacteria, and parasites, as well as cancer cells and foreign objects, such as wood splinters—distinguishing them from the organism's own healthy tissue.
- Many species have two major subsystems of the immune system.
- The innate immune system provides a preconfigured response to broad groups of situations and stimuli.
- The adaptive immune system provides a tailored response to each stimulus by learning to recognize molecules it has previously encountered.
- Both use specialised molecules and cells to perform their functions.