The Immune System: The Never-Ending War That Keeps You Alive

The human body is constantly bombarded by millions of viruses, bacteria, and other disease-causing microorganisms, or pathogens. Fortunately, most of these are thwarted by the body's own protective physical and chemical barriers, such as the skin, saliva, tears, mucus, and stomach acid.

Levels of Protection:

• Skin: The first line of defense and it does a good job at keeping things out of they body, but it can fail when there are fresh cuts.
• Saliva: Many foreign microorganisms that enter the mouth are destroyed by saliva.
• Mucus: This is that sticky stuff found in your nasal passages and the trachea. It's sticky because it's designed to trap foreign organisms. When you are ill your body produces more mucus, that's why you get stuffed up.
• Cilia: These are tiny little hairs found in the nasal passages that help trap foreign organisms. These little hairs also push what they've captured outward so that they can be expelled from the body.
• Coughing and Sneezing: Normally involuntary reactions to foreign objects in the upper respiratory system and designed to expel things with a great deal of force.

The millions of bacteria that live on the skin and the body's mucous membranes also help protect against certain invaders. When a pathogen does manage to evade these defenses and enter the body, it is attacked almost immediately by one or more components of the immune system.

The immune system uses extremely sensitive chemical sensors to recognize a foreign organism or tissue, especially one that can cause disease. Sometimes it overreacts to a harmless substance, such as pollen, a certain food, or medication; this can set the stage for an allergic reaction. In other cases, the immune system mistakenly attacks normal body tissue as if they were foreign, resulting in an autoimmune disease such as lupus or rheumatoid arthritis. Most of the time, however, the immune system holds fast as our first line of defense against a host of potentially deadly diseases.

Although our lymphatic system covers the entire body, most lymph nodes are clustered in the neck, armpits, abdomen, and groin. Fluid that drains from body tissues into the lymphatic system filters through at least one lymph node, where layers of tightly packed white blood cells attack and kill any harmful organisms. Blood vessels transport white blood cells, antibodies, and other protective substances produced by the immune system. The lymphatic system also returns body fluid to the bloodstream after it has been filtered through lymph nodes.

Disease-causing organisms vary from tiny viruses and bacteria to parasites such as the tapeworm, which can grow 20 feet long. Regardless of the size or species of the invading organism, a healthy immune system will mount a vigorous defense against it. The exact nature of that defense varies, however, according to the type and number of invading organisms.

Things That Can Go Wrong

Autoimmune Deficiency: As mentioned above, this is an illness where the body's own immune system begins to attack its own tissue. This can be organs, joints, muscles, and even the brain. One such common disease is Rheumatoid Arthritis. The specific reason this occurs is not known, but there are some known triggers. For example, if someone becomes infected with a bacteria the immune system will attack that bacteria. However, even after the bacteria has been destroyed the attack continues uncontrolled. Other triggers could include viruses, parasites, toxins, and cancer. There is no known cure for autoimmune deficiency, but in some cases there are medications that can reduce the rate of attack. Once someone has an autoimmune disorder it is usually for life. There is a genetic predisposition to this illness, meaning some people are more prone to developing it than others. There is no known way to prevent this disease. Once someone has this disease, immune depressing medication may be taken, however, this will reduce the effectiveness of the immune system and will make the person more prone to infections that they normally would not get.

Pathogens Multiplying Excessively: In almost all situations where something invades the body there is a period of time between the infection and when the immune system can get its soldiers to start defending. During this time the pathogen will continue to multiply. In some cases it is possible that the pathogen will multiply faster than the immune system can respond. When this happens, medical intervention is required (e.g. antibiotics), especially in the very young, the old, or anyone with a compromised immune system such as HIV.

Poor Recognition of Foreign Objects: It is possible that the immune system does not recognize the foreign organisms as foreign. This is more common with viruses, because they take over human cells, and in people with compromised immune systems.

Poor Immune System: This occurs in situations where White Blood Cell (WBC) count is low. These are the cells responsible for destroying pathogens. Examples that can cause this include:

• Chemotherapy
• Poor bone marrow functioning – this is where WBCs are made
• Certain medications
• HIV/AIDS
• Over-active spleen, which is the organ responsible for the proper destruction of WBC
• Leukemia which is cancer of the bone marrow
• Malnutrition and vitamin deficiencies resulting in an immune system that is not able to stay strong and rebuild
• Congenital disorders

Strengthening the Immune System

Proper Nutrition: The immune system needs to have the proper nutrients in order to stay effective. These nutrients include vitamins and minerals. Sometimes, even the lack of one nutrient can seriously damage the system's ability to function. However, these nutrients need to be in the body all the time. Loading up on vitamin C once you are infected with the common cold will do very little in helping your immune system to repel the bacteria.

Getting Vaccinated: These are laboratory produced proteins that resemble a real virus, but in an inactive form. When taken, usually by injection, they mimic the real virus and cause the immune system to produce antibodies, proteins that recognize the foreign virus. These antibodies can stay in the body for years offering protection. However, they are virus specific. This means they only protect against the specific virus designed for. Once an infection has occurred vaccines can still be used, but with some infections they will be less effective. There are several vaccines that one should get starting when they are young age in order to protect from serious infection.

Taking Antibiotics: These are drugs designed to fight bacterial infections. Their primary purpose is to destroy the invading bacteria in order to give the body's immune system a fighting chance. Unfortunately, the overuse of antibiotics has lead to many infections, previously wiped out, in making a comeback. This happens because bacteria adapt and evolve into stronger versions of their former selves.

Getting Sick: From a very young age, each time a child gets sick, their immune system gets stronger. Parents that over-protect their kids from all germs may actually be doing them a long-term disservice.

Breastfeeding: When a baby is first born its immune system is very week. It does not have any antibodies. However, if breast fed, antibodies will be passed on from the mother to the baby, offering it some protection until its own system develops and strengthens.

Avoiding Stress: Until a few years ago this was not recognized as an important factor. However, it is now well understood that prolonged and excessive stress will damage the immune system making the person more prone to all sorts of illnesses. So, learning to deal with stress is vital in keeping the immune system healthy.