Repetitive-stress injuries (RSIs) can be painful and debilitating, causing damage to tendons, ligaments, nerves, and muscles over time. Also called repetitive motion syndromes, RSIs can affect almost any part of the body. Test your knowledge of RSIs by taking this multiple-choice quiz.

True or false: If you have Raynaud's phenomenon, you will know it because of your fingers and toes change color.

Radon is a gas that you can't see or smell, but is present in nearly all the air around us. Everyone breathes in radon every day, usually at low levels. People who inhale high levels of radon are at increased risk for developing lung cancer. Radon is a problem in homes in which higher concentrations collect. Find out more about radon by taking this quiz.

Paget disease is a condition that affects the bones, usually causing them to become enlarged and deformed. Worldwide, it is the second most common bone disease. Learn more about Paget's disease by taking this quiz.

Getting older doesn't have to mean getting wider, the experts say. The first step in the fight against flab is knowing your opponent. Take the following quiz to find out how well armed you are.

The nervous system is responsible for our thoughts, our emotions and our movements. The brain, nerves and spinal cord are all members of this important process. How much do you know about the nervous system? Do you know what happens when the system malfunctions? Find out by taking this multiple-choice quiz.

Multiple sclerosis is a disease of the central nervous system, the brain and spinal cord. Its symptoms can range from benign to severe. Find out more about this mysterious illness by taking this quiz.

Today, more women than ever before are giving birth to multiples. What explains the increase through the past decade? Take this quiz to find out.

The most common mosquito-borne disease is dengue. It affects nearly 400 million people worldwide each year. Find out more about mosquito-borne diseases by taking this quiz.

Answer this one: Mercury in its elemental form is relatively nontoxic. In the environment, however, the elemental form of mercury is transformed into an organic form, which is easily absorbed by living things. This organic form, which builds up in the body, is called what?