The immune system provides the body with an intricate network of defense mechanisms that allow it to recognize, eliminate or neutralize potentially harmful foreign invaders. There are three main lines of defense: physical barriers such as your skin; non-specific inflammatory responses, in which blood brings chemical substances to injured areas; and specific immune responses, which occur when your body learns to recognize certain invaders and eliminate them if they return.
Friend or Foe
The key to efficient immune response is your body’s ability to distinguish between your own cells and foreign invaders. When immune defenders encounter cells or organisms with “outsider” characteristics, they quickly launch an attack.
Immune System Organs
Lymphoid organs of the immune system are found throughout your body. They’re home to lymphocytes (B-cells and T-cells), the small white blood cells that are key players in your immune system.
- GALT (Gut-associated lymphoid tissue): Over 2/3 of your total immune system cells are found in your intestinal lining. GALT interacts with friendly bacteria to optimize immune function.
- Lymph nodes: There are about 500 to 700 of these small, bean-shaped glands located in areas such as your neck, groin, underarms and abdomen. They produce and store infection-fighting cells and lymph, the clear fluid that carries these cells throughout the body.
- Thymus: A small organ located just behind your breastbone, this is where your T-cells (“t” for “thymus”) develop. When activated, T-cells transform from harmless immune cells into killer cells that seek out and destroy all traces of invaders.
- Spleen: Your spleen is located in the upper-left part of your abdomen and is about the size of your fist. It contains white blood cells that fight infection and destroys old or damaged red blood cells.
- Bone Marrow: The yellow tissue in the center of your bones is responsible for making white blood cells that are destined to become lymphocytes.