What Makes You Tick? Heart Facts

Every day, your heart beats (which means it expands and contracts) an impressive 100,000 times. That adds up to more than 2.5 billion heartbeats in the average lifetime.

Even if all the nerves to your heart were cut, it would keep beating if separated from your body. That's because the heart has its own electrical system. It just needs oxygen to keep beating.

A heart that's bigger than it should be is called an enlarged heart. It can become weak and pump blood less efficiently. It can beat irregularly, and fluid can congest your lungs. Sometimes you can help prevent this by taking care of your heart -- eat healthy, exercise, and watch your weight. Otherwise, drugs and devices like pacemakers can help treat the condition.

A stressful event, like a breakup or even winning the lottery, can bring on sudden chest pains that feel like a heart attack. Those pains are triggered by a rush of stress hormones. The good news is that "broken heart syndrome" is usually treatable and goes away within a couple of weeks.

You likely put your hand on the left side of your chest when thinking of your ticker. Your heart is in the center, though, between your lungs. The bottom of your heart is tipped to the left, which is why you feel it beating a little more on that side.

Your heart is a strong muscle that pumps blood to all the organs in your body --  2,000 gallons' worth each day! During an average lifetime, a heart will pump 1 million barrels of blood.

On Dec. 3, 1967, South African cardiac surgeon Christiaan Barnard transplanted a heart from a 25-year-old who died in an accident into a 53-year-old man. The man died 18 days later of pneumonia, but Barnard considered the transplant a success. It was followed days later by the first American transplant at Stanford University in California. Now, thousands of heart transplants are done worldwide each year, with roughly 75% of patients surviving for more than 5 years.

You have two upper chambers (left and right atria) and two lower chambers (left and right ventricles). They're separated by a wall of muscle called the septum. The left ventricle is the largest, strongest chamber. It pushes blood through the aortic valve and into your body.

Apes' and monkeys' hearts are closest to humans'. Their hearts are similar in how they look and work. But many scientists studying the use of animals as organ donors for people think the pig might be the most promising. Lots of research is being done.

Scientists used to believe that once an organ is grown it doesn't make any more cells. But research has found that the heart and other organs keep making new cells, at least in limited amounts. They could replace damaged ones caused by, for example, a heart attack.

No one knows for sure when the heart was first associated with the idea of love and romance. It became very common in the Middle Ages in works of art. It symbolized love, sincerity, and clarity.

Metal detectors likely won't cause problems for people with pacemakers. But the Transportation Security Administration asks that people with a pacemaker, defibrillator, or other internal medical device not go through the metal detector. Instead, ask for a pat down or to go through the imaging-technology scan.

The American Heart Association suggests avoiding machines with powerful magnets, like MRIs. Some MP3-player headphones shouldn't be kept near a pacemaker either.