Step One: Defend
When an invader attempts to enter the body, it must first cross multiple barriers such as our mucus membranes and skin. If the invader enters the body, white blood cells quickly recognize the pathogen as an invader and begin to coordinate the defense system. Soon, other defender cells, such as killer cells, macrophages and phagocytes come to help destroy the invader. White blood cells begin to produce an antibody to defend against any future attacks. The body produces more than one billion different antibodies to combat many types of invaders.
Step Two: Attack
These invaders are then attacked and destroyed by natural killer cells. The killer cell binds to its target, aims its weapons and then delivers a lethal burst of chemicals that produces holes in the target cell's membrane. Fluids leak out and the cell bursts.
Step Three: Cleanse
Macrophages, the "garbage men" of the body, have tentacles that grab the destroyed organisms and engulf them. The function of the macrophage is to ingest any foreign particles, including aged body cells.
Step Four: Repair
Damaged areas are repaired and the normal, healthy condition of the body is restored. Mast cells release histamine and heparin which stimulate other cells to open the blood vessels, thereby increasing circulation and allowing the process of cell and tissue regeneration.
