We see and hear about hearts everywhere. A long time
ago, people even thought that their emotions came from their hearts, maybe because
the heart beats faster when a person is scared or excited. Now we know that emotions
come from the brain, and in this
case, the brain tells the heart to speed up. So what's the heart up to, then? How
does it keep busy? What does it look like? Let's find out.
The Heart Is a Muscle
Your heart is really a muscle. It's located
a little to the left of the middle of your chest, and it's about the size of your
fist. There are lots of muscles all over your body — in your arms, in your legs,
in your back, even in your behind.
But the heart muscle is special because of what it does. The heart sends blood
around your body. The blood provides
your body with the oxygen and nutrients it needs. It also carries away waste.
Your heart is sort of like a pump, or two pumps in one. The right side of your
heart receives blood from the body and pumps it to the lungs. The left side of the
heart does the exact opposite: It receives blood from the lungs and pumps it out to
How the Heart Beats
How does the heart beat? Before each beat, your heart fills with blood. Then its
muscle contracts to squirt the blood along. When the heart contracts, it squeezes
— try squeezing your hand into a fist. That's sort of like what your heart does
so it can squirt out the blood. Your heart does this all day and all night, all the
time. The heart is one hard worker!
Parts of the Heart
The heart is made up of four different blood-filled areas, and each of these areas
is called a chamber. There are two chambers on each side of the heart. One chamber
is on the top and one chamber is on the bottom. The two chambers on top are called
the atria (say: AY-tree-uh). If you're talking only about one, call
it an atrium. The atria are the chambers that fill with the blood
returning to the heart from the body and lungs. The heart has a left atrium and a
The two chambers on the bottom are called the ventricles (say:
VEN-trih-kulz). The heart has a left ventricle and a right ventricle. Their job is
to squirt out the blood to the body and lungs. Running down the middle of the heart
is a thick wall of muscle called the septum (say: SEP-tum). The septum's
job is to separate the left side and the right side of the heart.
The atria and ventricles work as a team — the atria fill with blood, then
dump it into the ventricles. The ventricles then squeeze, pumping blood out of the
heart. While the ventricles are squeezing, the atria refill and get ready for the
next contraction. So when the blood gets pumped, how does it know which way to go?
Well, your blood relies on four special valves inside the heart. A valve lets something
in and keeps it there by closing — think of walking through a door. The door
shuts behind you and keeps you from going backward.
Two of the heart valves are the mitral (say: MY-trul) valve
and the tricuspid (say: try-KUS-pid) valve. They
let blood flow from the atria to the ventricles. The other two are called the aortic
(say: ay-OR-tik) valve and pulmonary (say: PUL-muh-ner-ee)
valve, and they're in charge of controlling the flow as the blood
leaves the heart. These valves all work to keep the blood flowing forward. They open
up to let the blood move ahead, then they close quickly to keep the blood from flowing
How Blood Circulates
You probably guessed that the blood just doesn't slosh around your body once it
leaves the heart. It moves through many tubes called arteries
and veins, which together are called blood vessels. These blood
vessels are attached to the heart. The blood vessels that carry blood away from the
heart are called arteries. The ones that carry blood back to the heart are called
The movement of the blood through the heart and around the body is called circulation
(say: sur-kyoo-LAY-shun), and your heart is really good at it — it takes less
than 60 seconds to pump blood to every cell in your body.
Your body needs this steady supply of blood to keep it working right. Blood delivers
oxygen to all the body's cells. To stay alive, a person needs healthy, living cells.
Without oxygen, these cells would die. If that oxygen-rich blood doesn't circulate
as it should, a person could die.
The left side of your heart sends that oxygen-rich blood out to the body. The body
takes the oxygen out of the blood and uses it in your body's cells. When the cells
use the oxygen, they make carbon dioxide and other stuff that gets carried away by
the blood. It's like the blood delivers lunch to the cells and then has to pick up
The returning blood enters the right side of the heart. The right ventricle pumps
the blood to the lungs for a little freshening up. In the lungs, carbon dioxide is
removed from the blood and sent out of the body when we exhale. What's next? An inhale,
of course, and a fresh breath of oxygen that can enter the blood to start the process
again. And remember, it all happens in about a minute!
Listen to the Lub-Dub
When you go for a checkup, your doctor uses a stethoscope to listen carefully to
your heart. A healthy heart makes a lub-dub sound with each beat. This sound comes
from the valves shutting on the blood inside the heart.
The first sound (the lub) happens when the mitral and tricuspid valves close. The
next sound (the dub) happens when the aortic and pulmonary valves close after the
blood has been squeezed out of the heart. Next time you go to the doctor, ask if you
can listen to the lub-dub, too.
Pretty Cool — It's My Pulse!
Even though your heart is inside you, there is a cool way to know it's working
from the outside. It's your pulse. You can find your pulse by lightly pressing on
the skin anywhere there's a large artery running just beneath your skin. Two good
places to find it are on the side of your neck and the inside of your wrist, just
below the thumb.
You'll know that you've found your pulse when you can feel a small beat under your
skin. Each beat is caused by the contraction (squeezing) of your heart. If you want
to find out what your heart rate is, use a watch with a second hand and count how
many beats you feel in 1 minute. When you are resting, you will probably feel between
70 and 100 beats per minute.
When you run around a lot, your body needs a lot more oxygen-filled blood. Your
heart pumps faster to supply the oxygen-filled blood that your body needs. You may
even feel your heart pounding in your chest. Try running in place or jumping rope
for a few minutes and taking your pulse again — now how many beats do you count
in 1 minute?
Keep Your Heart Happy
Most kids are born with a healthy heart and it's important to keep yours in good
shape. Here are some things that you can do to help keep your heart happy:
Remember that your heart is a muscle. If you want it to be strong, you need to
exercise it. How do you do
it? By being active in a way that gets you huffing and puffing, like jumping rope,
dancing, or playing basketball. Try to be active every day for at least 30 minutes!
An hour would be even better for your heart!
Eat a variety of healthy foods and avoid foods high in unhealthy fats, such as
saturated fats and trans fats (reading food
labels can help you figure out if your favorite snacks contain these unhealthy
Try to eat at least five servings of fruits and vegetables each day.
Avoid sugary soft drinks and fruit drinks.
Don't smoke. It can damage
the heart and blood vessels.
Your heart deserves to be loved for all the work it does. It started pumping blood
before you were born and will continue pumping throughout your whole life.