The kidney's main job is to get rid of excess fluid and waste material in your blood. A person with kidney failure needs dialysis or a kidney transplant to survive. Learn more about dialysis by taking this quiz.

Cystic fibrosis (CF) is an inherited, often fatal disease of the body's mucus glands. It affects about 30,000 children and young adults in the United States, most of them descendants of people from northern Europe. Find out more about CF by taking this quiz.

True or false: More than 200 viruses cause colds.

Answer this one: The STD chlamydia is a bacterium that is transmitted through intimate physical contact. What's the most common means of transmission?

Death rates from cervical cancer are dropping, because more women are being screened. To learn more about cervical cancer and prevention, take this quiz.

Celiac disease is a digestive disease that can affect children and adults alike. Also known as celiac sprue ("sprue" means you can't absorb nutrients from food), this disease is the most common genetic disease in Europe and is considered significantly underdiagnosed in the United States. Learn more about the disease by taking this quiz.

There are millions of pet cats in the U.S. Sometimes cats can cause an illness called cat scratch disease. Find out more about this illness by taking this quiz.

True or false: If someone is following your car too closely, you should gently tap your brakes as a warning.

The carpal tunnel is a pathway inside your wrist that carries the median nerve from your arm to your hand. Carpal tunnel syndrome is a condition that affects your hand. Test your knowledge of carpal tunnel syndrome by taking this quiz.

Is there a link between heavy caffeine consumption and osteoporosis? Find out when you take this quiz.