Heart quiz: Put your heart smarts to the test

The human heart is shaped like a cone. The narrower end of the heart points down and to the left side of the chest. In an adult, the heart weighs about three-fourths of a pound and is about the size of a fist. Major arteries, such as the aorta and pulmonary arteries, connect at the wider upper part of the heart. If arteries become clogged with cholesterol and other fatty deposits (atherosclerosis), you may have a heart attack or stroke.

If your heart muscle is weak, it can't pump as hard. To compensate for its inability to pump out the normal amount of blood, your heart may enlarge (dilate). It could eventually enlarge so much that it fails to function normally.

Jogging and other vigorous physical activity clearly benefit your heart. But even simple exercise like a brisk walk or pulling weeds in your garden strengthens your heart. The key to getting some heart-healthy benefits from walking or other simple exercise is that you do it consistently. The American Heart Association recommends getting 30 minutes of exercise — even if it's just a brisk walk — on most days of the week. Even short 10-minute walks that add up to 30 minutes count. Gardening and housework (vacuuming or other physical work) count, too!

The atria are small receiving chambers for blood returning from the body (right atrium) or from the lungs (left atrium). They push the blood into the ventricles with a rather weak contraction. The two ventricles are the main pumping chambers. The right ventricle forcefully pumps blood to the lungs, while the left ventricle pumps blood to tissues and organs throughout the body.