The Heart

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!

Diagram of the heart in the body

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.

Diagram of the heart chambers
Diagram of the heart chambers

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?

Diagram of blood circulation through the heart
Diagram of blood circulation through the heart

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.

Diagram of heart valves

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

Heart shape with heart beat graph

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.

Diagram of different types of hearts

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?

Doctor listening to a 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:

  1. Get Active
  2. Eat a healthy diet
  3. Maintain a healthy weight
  4. Control cholesterol
  5. Manage blood pressure
  6. Reduce blood sugar
  7. Don’t smoke or stop smoking