The immune system is crucial to our survival as it allows us to live a healthy and relatively disease free life. Without it, what we view as normal things around us, can become hazardous and we would have to live in sterile environments.
The immune system is very complex and works both alone and in conjunction with every other system in the body. The lymphatic system is the main component of the immune system. Lymph fluid is carried through the body in lymph nodes. The lymph nodes are most prominent in the armpits, groin and throat areas; when there is an infection being fought, these nodes often swell up and can be visible. Lymphocytes and white blood cells are contained in the lymph fluid which circulates through out the body.
The white blood cells are the most important in fighting infection as they destroy diseased or foreign cells. An increase in white blood cells is a sure sign that there is an infection in the body. This is why some HIV tests also include a white blood cell count.
The bone marrow produces both the white and red blood cells. When leukemia, which is cancer of the bone marrow occurs, an increased number of abnormal white blood cells and immature red blood cells are produced and released. This causes a dysfunction in the immune system. Other helpful accomplices in the immune system are nose hair and mucus in the throat and lungs which trap bacteria before it affects the body.