Our bodies are continually being attacked by bacteria and viruses. We must have defense mechanisms or otherwise we would be sick all the time.
Defense mechanisms fall into two categories:
Another major disease, smallpox, raged for hundreds of years in all parts of the world. The disease was so common and deadly that a worldwide campaign to eliminate it began when a vaccine was developed. The vaccine left a scar on the skin, but it was worth it to prevent smallpox. Because so many people around the world were vaccinated, the disease has apparently disappeared. No reports of smallpox have appeared since 1979, when it was declared to be eradicated. (Access more information about the role of vaccination in eradicating smallpox.)
Of course, we don't always have vaccines that work against
some diseases. Throughout this unit, we will learn
how the body fights diseases both with and without the help of vaccines.
We will introduce the structures and functions involved in bodily defenses
that keep you safe and healthy.