The immune system is a network of cells, tissues, and organs that work together to protect the body from infection. The immune system recognizes and destroys foreign invaders such as bacteria, viruses, and fungi. It also helps the body heal from injuries.
The immune system is made up of two main types of cells: white blood cells and antibodies. White blood cells are the body’s first line of defense against infection. They engulf and destroy foreign invaders. Antibodies are proteins that attach to foreign invaders and help white blood cells destroy them.
There are three main types of immunity: innate immunity, acquired immunity, and active immunity. Innate immunity is the immune response that a person is born with. Acquired immunity is the immune response that a person develops after exposure to an infectious agent such as a virus or bacterium. Active immunity is the production of antibodies in response to an infection or vaccination.
The lymphatic system is a network of vessels and nodes that transports lymph fluid throughout the body. Lymph fluid contains white blood cells that help fight infection. The lymphatic system also helps remove excess fluids from tissues and helps transport fats from the digestive system to be used for energy by other tissues in the body