The purpose of the immune system is to protect the body from infections and harmful substances. It defends against disease-causing germs such as bacteria, viruses, parasites, and fungi, and removes them from the body. It also recognizes and neutralizes harmful environmental substances and fights disease-causing changes within the body, such as cancer cells
. The immune system achieves this through a complex network of cells, tissues, organs, and proteins that work together to identify and eliminate threats. Key components include white blood cells (leukocytes), lymphocytes (B cells and T cells), the spleen, bone marrow, thymus, lymph nodes, tonsils, and lymphatic vessels
. When the immune system detects foreign antigens-proteins on pathogens or abnormal cells-it triggers an immune response. This involves producing antibodies to mark invaders for destruction and activating cells that directly attack infected or abnormal cells. The immune system also has memory, enabling it to respond faster and more effectively upon subsequent exposures to the same pathogen, providing immunity
. In summary, the immune system's purpose is to:
- Identify and eliminate infectious agents and harmful substances
- Protect the body from infections and cancerous changes
- Remember past invaders to provide faster future responses
- Maintain the body's health by distinguishing self from non-self
