How Does The Immune System Work?

Our body's defenses protect us from microbe invasion in many ways. For example, the skin not only shields us from attack, but it also hosts billions of friendly bacteria that destroy harmful strains that often contaminate its surface. This system works well unless harsh chemicals and soaps drastically alter natural conditions on the outside of the body.

Another line of defense, saliva, is antiseptic, as is mucus secreted by the lining along the digestive and urinary tracts. If you breathe in the microbes, mucus in the sinuses and the bronchiole tubes may catch them before they go deeper into the body cavity. Tears take care of those germs that find their way onto the eyes.

But what if the gastric, especially hydrochloric acid, doesn't completely protect you from microbes that are swallowed? Friendly bacteria in the colon will take care of them, if these friends have not been killed by antibiotics.

When these shields fail, both microbes and toxins can get into the blood and here is where the immune system goes quickly into action. Invading germs carry "markers" on their surfaces to help the immune system identify them as aliens. Once detected, nearby cells send out signals that alert the rest of the body (via the nervous system).

At first, interferon is produced by each cell under attack. This chemical temporarily holds the enemy at bay until the immune system can calculate more precisely what it is fighting. The body is so efficient that it does not arm itself against every possible microbe invader in nature. Instead, it is ready with manufacturing machinery and spare parts at strategic points to produce tailor-made weapons and specially trained soldiers to meet each particular threat. Otherwise, the immune system would be so massive and costly to maintain that you probably would not have much energy left to do anything but breathe, eat and sleep!