Heart Facts
Heart [härt]
The muscular organ that pumps blood through the circulatory system.
The Heart
Every second of every day something incredible happens inside your body. One of your body's organs, the HEART, works day and night to constantly pump blood into your lungs where it loads up on oxygen, and then pumps blood out to the rest of your body where it delivers nutrients and oxygen and removes waste products. If this finely tuned engine stopped you'd be dead in minutes!

Let's investigate the heart's valves, chambers, and vessels, uncover what they do and how they work!
Where is your heart?
Your heart is in the center of your chest. Your heart is not right under your skin but lies behind your breastbone, inside your ribcage, and between your lungs. Take a closer look its anatomy.
How big is your heart?
The heart is about the size of your fist. When you were a baby it was the size of your baby fist.
What does the heart look like?
The heart is a muscle, just like the other muscles in your body!! It weighs about a pound, or less than half a kilogram.

What are the heart's chambers?
The heart has four chambers, which you can think of as “rooms” of the heart. There are two atria and two ventricles. The atria receive blood from the body and the lungs, and the ventricles pump blood back out, first to the lungs and then to the body.
Read more about heart chambers, then label the heart parts.
What does the heart do?

This muscle, which beats at about 70 times a minute, pumps blood in a one-way path around your body through blood vessels. The heart and the vessels together are called the circulatory system. The heart valves stop blood from flowing the wrong way.
The heart pumps thousands of liters of blood through your body every day. Blood is pumped out of the heart in two directions. First it sends blood without any oxygen from the right ventricle to the lungs to get oxygen. After the oxygen-filled blood comes back to the heart — to the left atrium — it is pumped from the left ventricle to all the other parts of the body. After delivering its oxygen, the blood returns to the heart — to the right atrium — to start the process of getting oxygen all over again.
Watch your blood flow through the heart.
What do the valves do?
Between the chambers there are valves which stop blood from flowing the wrong way. The valves open and close and help to move blood through the heart to the right place at the right time.

When the valves open, blood surges into the chambers. The valves close, the heart contracts, and the blood flows out. For another view, watch this demonstration.
About your Heart Beat

The human heart beats over two and a half billion times in a lifetime. The heart's rate when you are a baby is about 120 beats per minute. As you grow, your heart rate slows. A seven-year-old child's heart beats about 90 times per minute. By the age of 18, the heart rate is about 70 beats per minute. Watch this Sci Show video on how to feel your heartbeat.
During exercise, more oxygen and nutrients are needed by the muscles, so blood must be delivered faster than when the body is resting. To meet these demands, the heartbeat increases.
You can find your heartbeat. There are places on your body where you can feel your pulse, the beat of blood as it rushes through your veins and arteries. Your wrist is a good place to try.
Continue your tour by visiting Amazing Heart Facts.
Are all hearts the same?
Did you know that all vertebrate hearts are not the same? A mammal heart is different from a fish heart, for example, even though both mammals and fish are vertebrates.

Birds and mammals (humans are mammals) have a 4-chambered heart that separates oxygen-rich and oxygen-depleted blood. Fish have a 2-chambered heart. Amphibians have a 3-chambered heart with two atria and one ventricle. Some reptiles have a partial separation of the ventricle but others have a 4-chambered heart.
Who knows about the heart?

A Cardiologist is the special doctor who knows about the heart and circulatory system and about its functions and diseases. Read about the History of Cardiology.
While there have been many medical breakthroughs in treatments of heart disease, including surgery and transplants, a large number of people still die from heart-related illnesses each year. Watch an Open Heart Surgery Movie.
About 610,000 people die of heart disease in the United States each year. The average age for a first heart attack is about 65 for men and 72 for women. About 735,000 people in the U.S. have heart attacks (myocardial infarctions) each year. Of those, about 120,000 die. Learn about heart attacks.
What can you do to keep a healthy heart?
Those who are at a higher risk of suffering a heart attack or stroke (brain attack) are those who are overweight, are smokers, have high cholesterol, high blood pressure (hypertension), or diabetes.
Follow these Simple 7 steps to have a healthy heart for the rest of your life:
- Get Active
- Eat a healthy diet
- Maintain a healthy weight
- Control cholesterol
- Manage blood pressure
- Reduce blood sugar
- Don’t smoke or stop smoking
Fun Links
Watch Exploring the Heart, an animated video about the journey of a red blood cell as it goes through the chambers and valves of the heart, making deliveries to all parts of the body.
The Texas Heart Institute has a great site for kids! Anatomy Animations, facts, coloring pages, quizzes, experiments, virtual microscope, and more. Check it out!
KidsHealth offers extensive Heart information for Kids and Teens.
For younger students, print out this coloring page that will help you remember the difference between arteries and veins. And if you're ready for a challenge, check out Arizona State University's heart image and test yourself as you identify the parts of the heart.
Watch a pumping heart.
Enjoy this fun video about How The Heart Works.
PBS's NOVA has produced several shows on the heart. “Cut to the Heart” details what in 1997 was a new and controversial surgery. Highlights at the companion website include Pioneers of Heart Surgery and a photo collection of troubled hearts. In the interactive feature Map of the Human Heart, you can see exactly how your heart pumps blood throughout your body.
“Electric Heart” chronicles the quest to create an artificial heart and the surgeons and researchers who worked to bring it into being. The website features an interview with Dr. O. H. Frazier, one of the chief artificial heart researchers, and an interactive where you can conduct your own virtual heart transplant procedure! Have Fun!