Your Immune System

Your immune system is designed to defend against a constant barrage of virusus, bacteria, fungi, toxins and parasites. You can see it in action when:

• You get a cut, the opening provides entrance for bacteria and viruses
• When a mosquito bites you, the itchy bump is a sign of your immune system at work
• When you breathe, you take in thousands of germs, a cold or flu is an indication your immune system failed to stop one
• When you eat, you take in hundreds of microbes, some of them harmful, if your immune system fails to neutralize them, you could get food poisoning
• Allergies are signs that your immune system is working inappropriately, signalling defenses for harmless particles like dust, or cat dander
• When you get a blood transfusion or organ transplant, your immune system may work against the process by treating the transplant (or blood) as a harmful invader
• When you die, your immune system shuts down, all the things that bombard your body now have free access. Decomposition occurs in weeks as all these microbes consume your tissue
• Some diseases called Autoimmune Diseases occur as a direct result of the body's immune system not working properly. Example: arthritis, Lupus

The first Line of defense is the skin and mucous membrane, which also lines the gastrointestinal and respiratory passageways. The skin is tough and the high acidity of the stomach acts as an excellent disinfectant.

The Lymph System

Includes lumph nodes and lymph fluid. Lymph fluid is blood plasma (liquid that makes up the blood minus the red and white cells). Bacteria or other pathogens that enter the body find their way into this fluid, which is filtered through the lymph nodes. The lymph nodes then filter the fluid and remove these dangerous particles. These lymph nodes may swell when fighting an infection, hence you can feel those bulges at your neck when you're sick.

The Thymus - this organ lays between your breastbone and your heart. It is responsible for making T-cells.
Spleen - filters blood and removes any foreign particles and old blood cells in need of replacement. A person missing a spleen may get sick more often than one without a spleen
Bone Marrow - produces new blood cells, both red and white. The bone marrow produces all blood cells from STEM CELLS, which mature into different types of white blood cells.

White Blood Cells - also known as Leukocytes

Neutrophil - suicide bomber cells that destroy cells infected by a virus
Macrophages - consume pathogens
B Cells - mature into plasma cells when stimulated
Plasma Cells - produce antibodies specific to an invader
Cytotoxic (Killer) T Cells - bump into infected cells, poke holes in them and destroy them
Helper T Cells - activate Killer T cells and B cells

collectively called phagocytes -- converge on the invaders and proceed to literally "eat them up." Generally the phagocytes will build up in one place, causing what we call puss -- in order to eliminate the waste.

 

Antigens and Antibodies

Antigens are substances that trigger an immune response. Cells infected by viruses displace antigens on their surfaces. These antigens are recognized by other cells.

Antibodies are the bodies best defense against viruses. However, antibodies are specific in their actions, that is that a chickenpox antibody will only attack a chickenpox virus. Thus a particular virus stimulates the production of a particular antibody.

The Immune System Activated (See Step-by-Step Version)