11 Surprising Facts About Your Heart

The hardest-working muscle in your body is your heart, according to the Library of Science's Mysteries series.

It pumps out 2 ounces of blood at every heartbeat, adding up to at least 2,500 gallons daily. The heart has the ability to beat over 3 billion times in a person's life.

If you want to stay heart healthy, it might make sense to cut back on driving and watching the tube. In one analysis of data from nearly 30,000 people in 52 countries, those who owned both a car and TV had a 27% higher risk of heart attack than those who owned neither.

However, the researchers caution that lack of physical activity—not the cars or TVs themselves—are the culprit.

Just like it helped the new, slimmed down Mario Batali, who extols a Mediterranean diet, which emphasizes eating foods like fish, fruits, vegetables, beans, high-fiber grains, and olive oils rich with monounsaturated fats, fiber, and omega-3 fatty acids, and limits eating cheese and sweets. Studies suggest people with heart disease who follow this diet can prevent a second heart attack, and that the diet is good for your heart even without weight loss.

We've always known pollution is bad for your lungs. Now scientists are finding that it's also toxic for your heart, even at low levels, according to research conducted at the Heart Institute of the Good Samaritan Hospital and the Keck School of Medicine, University of Southern California, both in Los Angeles.

When pollutants are inhaled, they trigger an increase in "reactive oxygen species," which are superoxiding molecules that damage cells, cause inflammation in the lungs, and spark a cascade of harmful effects in the heart and cardiovascular system. Hearts exposed to pollution are also at higher risk for arrhythmias.

Losing a loved one can bring overwhelming feelings of grief, depression, and anger. For some people, the shock and stress of bereavement may even bring on a heart attack. A new study of nearly 2,000 heart-attack survivors found that attacks were far more likely to happen soon after the death of a family member or close friend than at other times. The risk of having a heart attack appears to decline as grief subsides.

Notice when people say the Pledge of Allegiance, that they place their hands slightly to the left on the chest? That's because most people think their hearts are on the left sides. The truth is, your heart is dead center in the middle of your chest, though it feels like it's tilted to the left because the largest part of your heart is on the left. Your left lung is smaller than your right to make room for your heart. People with dextrocardia, a defect, have their hearts on the right side.

Coffee drinkers are less likely to be hospitalized or worried about heart rhythm disturbances, even though the caffeine in coffee can make the heart beat faster, finds a surprising new study by the Kaiser Permanente Division of Research in Oakland, Calif. The researchers found that those who reported drinking four or more cups of coffee each day had an 18% lower risk of hospitalization for heart rhythm disturbances. Those who reported drinking one to three cups each day had a 7% reduction in risk.

They note that the study does not suggest a cause and effect, and most heart experts are not likely to prescribe coffee as a protective dietary beverage any time soon.

The average heart weighs between 7 and 15 ounces (about what an apple weighs) and is a little larger than the size of your fist.

It begins beating about 22 days after conception, and ends, well, when you do. By the end of a long life, a human heart can beat up to 3.5 billion times, according to the Texas Heart Institute.

About 78 beats per minute, in fact. The male heart beats about 70 beats per minute. But before conception, male and female hearts beat at about the same rate.

That, say heart experts, is simply a myth.