Matters of the heart have baffled humans since the dawn of time, with sonnets and entire books devoted to the meaning of love. Now scientists are finding that the blood pump in your chest is just as complex. You can't live or <i>love</i> without it. Find out the sappy scoop on the heart, including how sex and laughter are indeed good for it, and how bad news really can break it.
Weighing in at 10 ounces, the blood-filled muscle called the heart has become the universal symbol of <a href=http://www.livescience.com/humanbiology/050531_love_sex.html target=new>love</a>. The <a href=http://www.livescience.com/history/070202_greek_nudity.html target=new>Greeks</a> believed the heart was the seat of the spirit, the Chinese associated it with the center for <a href=http://www.livescience.com/humanbiology/060227_happiness_keys.html target=new>happiness</a> and the Egyptians thought the emotions and intellect arose from the heart. No one is sure the exact origin of the love association, however. One idea is that the heart got its "love mark" in the ancient Greek city of Cyrene, now in modern-day Libya. The colony was known for a plant called Silphium, with heart-shaped seed pods. Silphium had medicinal properties, and possibly also was used as an herbal contraceptive.
Alas, a broken heart can cause one to swoon. A <a href=http://www.livescience.com/humanbiology/060303_heart_risk.html target=new>breakup with a loved one</a> or <a href=http://www.livescience.com/humanbiology/ap_heartbreak_050209.html target=new>news of a family death</a> literally can lead to broken hearts in the form of heightened risk for heart attack, studies have shown. Such trauma can also trigger the release of stress hormones into the bloodstream that temporarily "stun" the <a href=http://www.livescience.com/othernews/050816_heart_timing.html target=new>heart</a>. The resulting symptoms mimic those of a <a href=http://www.livescience.com/humanbiology/051226_heart_attacks.html target=new>heart attack</a> - chest pain and shortness of breath - but this type of achy heart can <a href=http://www.livescience.com/humanbiology/ap_heartbreak_050209.html target=new>bounce back</a> in days with some TLC and rest.
In under a minute, your heart can pump blood to every cell in your body. And over the course of a day, about 100,000 heart beats shuttle 2,000 gallons of oxygen-rich <a href=http://www.livescience.com/humanbiology/050216_young_blood.html target=new>blood</a> many times through about 60,000 miles of branching <a href=http://www.livescience.com/humanbiology/060705_blood_vessels.html target=new>blood vessels</a> that link together the cells of our organs and <a href=http://www.livescience.com/php/trivia/?quiz=bodyquiz1 target=new>body parts</a>. That's a hefty job for a fist-sized muscle.
A glass of Merlot can go straight to the heart, and recent research shows that so too can the white variety. Scientists have attributed the heart benefits of <a href=http://www.livescience.com/healthday/536152.html target=new>reds</a> to grape skins, which are chock full of certain <a href=http://www.livescience.com/php/video/player.php?video_id=asb1009_winetherapy target=new>antioxidants</a>. Since the purple-hued skins get removed to make Chardonnays, many scientists had assumed white wine likely wouldn't do the heart any good. A lab experiment on rats showed that a grape's pulp conceals <a href=http://www.livescience.com/animalworld/061101_wine_diet.html target=new>cardio-protective compounds</a> that rival those found in reds. Red or white? Just follow your heart.
A hearty <a href=http://www.livescience.com/humanbiology/061212_contagious_laughter.html target=new>laugh</a> - the kind that sends a stream of <a href=http://www.livescience.com/humanbiology/070128_teardrop.html target=new>tears</a> from your <a href=http://www.livescience.com/mysteries/061019_cry_humans.html target=new>eyes</a> - does more than warm the soul. Research has shown the <a href=http://www.livescience.com/humanbiology/041111_laughter_therapy.html target=new>guffaw</a> can cause the lining of blood vessel walls called endothelium to relax, increasing blood flow for up to 45 minutes after the laugh attack. Damage to the endothelium can lead to the narrowing of blood vessels and eventually cardiovascular diseases. That's no laughing matter...or maybe it is...
Some people really do have bigger hearts than others. Rather than a <a href=http://www.livescience.com/humanbiology/051226_tough_hearts.html target=new>sign of affection</a>, an enlarged heart can signal underlying <a href=http://www.livescience.com/humanbiology/051226_heart_attacks.html target=new>heart disease</a>. The most common type, called dilated cardiomyopathy, occurs when the heart's chambers stretch out and enlarge. The bulging saps the heart's pump power, depriving the body's organs of enough blood. If left untreated, a big heart can lead to heart failure.
A seemingly sheepish look from <a href=http://www.livescience.com/humanbiology/051115_dog_friend.html target=new>Fido</a> or that endearing brush-by from your cat can make you wonder if your pet could possibly communicate with you. A recent study adds equine friends to the list of emotionally-responsive animals. A scientist found that horse's heart rates mirror those of human subjects touching them. The <a href=http://www.livescience.com/php/video/player.php?video_id=horse_rider_quest target=new>horse</a> emotion-detector could someday replace procedures used to measure a patient's <a href=http://www.livescience.com/imageoftheday/siod_051122.html target=new>stress hormones</a>. Next, the researcher will study <a href=http://www.livescience.com/php/video/player.php?video_id=dogs_ext_quest target=new>service dogs</a> to better match them with humans.
A love-torn heart can be painful enough to make you wish you could get a new heart or at least a cardio repair kit. Both of the latter options could some day be realities. Scientists are studying the <a href=http://www.livescience.com/imageoftheday/siod_061205.html target=new>red-spotted newt</a> to help them develop cell therapies for humans with physically damaged hearts. This amphibian can turn its cells back in time, as if they were <a href=http://www.livescience.com/healthday/600767.html target=new>stem cells</a>, in order to build up new heart muscle. In another study, scientists engineered a beating heart from embryonic <a href=http://www.livescience.com/biotechnology/ target=new>stem cells</a> in the lab.
Girls rule in some matters of the heart, but when it comes to research into cardiovascular disease it's the guys who come into the spotlight. For decades, heart disease and heart attacks have been viewed as a man's illness. But this is far from the truth. Heart disease kills 500,000 American <a href=http://www.livescience.com/humanbiology/051226_tough_hearts.html target=new>women</a> each year, topping male numbers by 50,000. Another gender gap: Women don't tend to experience the Hollywood-standard <a href=http://www.livescience.com/humanbiology/051226_heart_attacks.html target=new>heart attack</a> in which gripping chest pain sends you keeling over. Instead, women have reported tightness, aching or pressure in the heart, plus other symptoms like nausea, back and jaw <a href=http://www.livescience.com/humanbiology/051024_women_pain.html target=new>pain</a>.
If you can't make it to the gym, try fooling around. Your heart might thank you. A study of 2,500 men aged 49 to 54 found that having an <a href=http://www.livescience.com/php/trivia/index.php?quiz=sex target=new>orgasm</a> at least three times a week cut in half the likelihood of death from coronary heart disease. And barring underlying health issues and the possibility of contracting a sexually transmitted disease, <a href=http://www.livescience.com/humanbiology/050330_sex_good.html target=new>sex</a> can give you a workout. By some estimates, a vigorous <a href=http://www.livescience.com/humanbiology/060727_sex_history.html target=new>sex session</a> can double a person's heart rate and burn up about 200 calories, or the equivalent of a brisk 15-minute run. So staying in bed might be just what the doctor orders.