Encyclopedia of Homeopathy

204 • SERIOUS AILMENTSIMMUNE SYSTEMThe immune system is the collective name given to variousmechanisms that enable the body to defend itself againstinvasion by infection-carrying agents such as bacteria, viruses,fungi, and foreign proteins. The skin, certain glands, and thelymphatic system are all part of the immune system.How the system worksAny invading organism trying to enter thebody must break down the defensive barrierserected by the immune system. It willprobably pass through an area of broken skinor enter the respiratory and digestive tract viathe mouth or nose. There are glands alongthese routes that produce protective enzymesor natural antibiotic secretions, but if anorganism does break through into bodytissue, the immune system relies heavily onthe lymphatic system.The lymphatic systemThis body system consists of lymph vesselsthat carry lymph from the tissue spacesbetween cells all over the body to lymphglands, or nodes. Lymph is a clear fluidthat derives from plasma in blood fromwhich proteins and other nutrients havebeen removed. Lymph drains from thebloodstream into capillaries and then intothe lymph vessels. The flow of lymph iscontrolled by muscle contractions andvalves. Invading organisms are trappedin lymph glands dotted throughout thelymphatic system. Here they are attackedby scavenging white blood cells calledmacrophages. Lymph glands also producelymphocytes, another form of white bloodcell. Some lymphocytes (B-cells) produceantibodies that attack antigens on the surfaceof an invading organism (see page 206); otherlymphocytes (T-cells) destroy invadingorganisms directly.Lymphocytes have the ability to rememberinvaders that they have come across before,and so respond quickly if the body is invadedagain. On the other hand, the immune systemcan fail to spot invaders, or it can overreact—by developing allergies—or react abnormallyto the body’s own tissues, as in autoimmunediseases such as rheumatoid arthritis (see page197). Alternatively, it may fail to recognizethat its own cells have begun to functionabnormally, hence the development of cancer.Lymph drains frombody into right andleft subclavian veinWhite blood cellsmigrate from bonemarrow to thymusgland, where theydevelop into T-cellsLymph capillaries aresmallest vessels inlymphatic systemLymph vessels liejust beneath skinand roughly followvenous systemIMMUNE SYSTEM The immune systemis a complex network of glands, vessels,tissues, and organs that attempt toeliminate harmful organisms that mightcause infection or disease in the body.Lymph vessels cover the whole body andare studded with lymph glands, massesof lymph tissue in which invadingorganisms are attacked. Lymph from allover the body is filtered by flowingthrough lymph glands beforedraining back into the bloodstream.Lymph gland isenclosed mass oflymph tissue thatacts as filterSkin is firstdefensive barrieragainst invadingorganismsAdenoids areglandularswellings thatprotect againstrespiratoryinfectionsTonsils are lymphoidtissues that guardagainst inhaled oringested organismsEnzymes secreted instomach destroyingested organismsPeyer’s patches areclusters of lymphtissue in lowersmall intestineWhite blood cellsare generated inbone marrow