The main parts of the immune system are:
White blood cells: Serving as an army against harmful bacteria and viruses, white blood cells search for, attack, and destroy bugs and viruses to keep you healthy. They are a key part of your Immune System. There are many types of white blood cells and each cell type either circulates in your bloodstream and throughout your body, or resides in a particular tissue, waiting to be sprung and unleashed into action – like your body snipers. Each of these cells has a specific mission in your body’s defense system. They all have a different way of recognizing a foreign invader, communicating with other cells on the defense team, and performing their function – to annihilate the invader. No mercy!
Lymph nodes: These small glands filter and destroy invading organisms so they can’t spread to other parts of your body and make you ill. They are also part of your body’s lymphatic system. Lymph nodes contain immune cells that analyze foreign invaders brought into your body. They then activate, replicate, and send specific white blood cells called lymphocytes to fight off a particular invader. You have hundreds of lymph nodes all over your body, including in your neck, armpits, and groin, and so on. Swollen, tender lymph nodes are a clue your body is fighting an infection. It is killing an invader. It is annihilating a bug of some sort.
Spleen: Your spleen stores white blood cells that defend your body from foreigners. Your spleen also filters your blood, destroying old and damaged red blood cells.
Tonsils and adenoids: Because they are located in your throat and nasal passage, tonsils and adenoids trap foreign invaders such as bacteria, or viruses as soon as they enter your body. They house immune cells that produce antibodies to protect you from any foreign invaders that cause throat and lung infections. Although fierce, they are totally on your side!
Thymus: This small organ in your upper chest beneath your breastbone helps nurture and mature specific types of white blood cells. The task of these calls is to learn to recognize and remember an invader so that an attack can be quickly mounted the next time this invader is encountered.