Human Immune System
The human immune system is like a country's defense system. It protects the body 24 hours a day from the attack of germs, bacteria, viruses and chemical toxins.
The main lymphoid organs of the immune system consist of the bone marrow and the thymus. The peripheral lymphoid organs include the tonsils, spleen, lymph node, Peyer's patches, and appendix.
Soldier Factory: Bone Marrow
The bone marrow creates red blood cells and white blood cells. Immune cells, or white blood cells, are like soldiers of the immune system, and hence the bone marrow is like a soldier factory.
Training Ground: Thymus
Just as soldiers train for war with the navy, or air force, the thymus assigns T cell their fighting duties. The thymus also secretes immune-regulating hormones.
Battleground: Lymph Nodes
Lymph nodes are little pockets of the battlegrounds where billions of white cells gather, ready to wage war. While fighting infections, lymph nodes enlarge with foreign invaders and white blood cells to a point where you can actually feel the swelling.
A swollen lymph node is a good indication that the immune system is hard at work against an infection. Lymph nodes also act as a drainage system - they filter the lymph fluid and remove foreign materials such as bacteria and cancer cells.
The body contains more lymph fluid than blood.
Throat Guards: Tonsils
The tonsils constantly guard against invasion via the nose and mouth. People who have had their tonsils removed show a marked increase in getting Hodgkin Lymphoma, indicating the importance of the tonsils in upper respiratory tract protection.
Immune Assistant: Appendix
The Appendix assists with B cell maturation and antibody (IgA) production. It coordinates traffic by producing molecules that direct white blood cells to other parts of the body.
Other duties of the Appendix are to inform white blood cells when there are invaders in the digestive tract and to suppress potentially harmful antibody responses while promoting local immunity.
Intestinal Guard: Peyer's Patches
Like the Appendix, Peyer's Patches react to invaders in the intestines. They are of vital importance to the human body in terms of controlling invading microorganisms in the bloodstream.
Blood Filter: Spleen
The spleen is a blood reservoir that filters the blood to remove dead blood cells and engulfed viruses or bacteria. The spleen also signals B cell to produce large quantities of antibodies.
Retrieved from Book Title: Nutrition·Immunity·Longevity By Dr. Jau-Fei Chen