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Learn more about the heart with this interactive page. 

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Learn more about the heart with this interactive page. 

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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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 the body.

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 right atrium.

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 backward.

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 veins.

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 trash!

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 ingredients).

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.

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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.

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The heart is a muscle in the body. The heart is divided into four parts. These parts are called chambers.

The job of each chamber is to pump blood to the organs of the body. The chambers of the heart are hollow so they can fill up with blood as it passes through each one.

This means the heart does not weigh very much, but without the heart, the body cannot live.

The four chambers or compartments of the heart are Left Ventricle, Right Ventricle, Left Atrium, Right Atrium.

Like the other organs in your body, your heart grows with the rest of your body. The heart is always about the size of your fist. This means that when you were born, your heart was about the size of your tiny baby fist, and will stop growing when you do.

There are two different kinds of 'tubes' coming off the heart that carry the blood from the heart to every part of the body. The two types of tubes are called veins and arteries.

Arteries carry blood away from the heart and veins bring blood back to the heart. This process is called circulation.

Circulation starts in the left ventricle of the t. The blood is pumped from there into the aorta, which is the largest artery in the human body. When it enters the aorta, the blood is filled with oxygen. The oxygen in the blood goes to every part of the body. Blood also carries hormones and other important nutrients and disease-fighting cells throughout the body.

While the blood is spreading oxygen and all those other things through the body, it is also picking up things we don't need-things like carbon dioxide. When the blood has gotten rid of the oxygen and other important things, it comes back to the heart-going into the right atrium. From there, the blood goes into the right ventricle. The right ventricle has an important job. It sends the blood into the lungs so it can be refueled with more oxygen. When this has happened, the lungs send the blood to the left atrium and the whole process starts all over again.

How long does it take for the blood to travel through the body?

It takes about 20 seconds for blood to travel throughout the body. That is pretty amazing because if you stretched out all the veins, arteries, capillaries, and vessels the blood travels through, you would have a 'rope' 60,000 miles long! That's long enough to circle the earth...twice!!!

But wait! Your heart beats more than every 20 seconds, so what's up with that?

report this ad It takes 20 seconds for blood to travel throughout your body. But your heart beats faster and more often than every 20 seconds because not all your blood goes through your body at one time. This means your heart is always pumping blood.

Have you ever noticed that sometimes your heart beats faster than it does at other times? Why is that?

How fast does your heartbeat

Here is what you need:

Yourself

Pen and paper

The help of an adult

Stopwatch, timer with seconds, or a clock with a second hand

Get familiar with checking your heart rate

To check your heart rate put your first two fingers over just below your jaw; pressing GENTLY and feeling for the spot where you can feel your pulse. If you are having trouble, ask a parent to help you.

Once you are confident you can check your pulse (heart rate) or have someone to do it for you, continue with the remaining steps in this experiment.

Standing still, take your heart rate and write down the number of beats per minute

Run in place for one minute, stop, take your heart rate and write down the number of beats per minute

Lay down for one minute, take your heart rate and write down the number of beats per minute

Walk around your house at a normal pace for one minute, take your heart rate and write down the number of beats per minute

Look at the results-when did your heartbeat the fastest

When did it beat the slowest

What was your highest heart rate?

What was your slowest heart rate?

The faster your body moves the more oxygen it takes for your body to function. This means your blood has to work harder and faster to get your body the oxygen it needs. So...to get it there faster, the heart has to pump faster-just like a car speeds up when you give it more gas.

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Heart Rate Experiment (Explained!) - Science for Kids

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The heart is a muscle in the body. The heart is divided into four parts. These parts are called chambers. The job of each chamber is to pump blood to the organs of the body. The chambers of the heart are hollow so they can fill up with blood as it passes through each one.

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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Watch the video about how the heart works.

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Watch the video about how the heart works.

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If you've ever wondered how your heart works, this movie has the answer. And special thanks to the Fred J. Brotherton Charitable Foundation for supporting this adventure!

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Larger text size Large text size Regular text size If you've ever wondered how your heart works, this movie has the answer. And special thanks to the Fred J. Brotherton Charitable Foundation for supporting this adventure!

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What Does the Heart Do?

The heart is a pump, usually beating about 60 to 100 times per minute. With each heartbeat, the heart sends blood throughout our bodies, carrying oxygen to every cell. After delivering the oxygen, the blood returns to the heart. The heart then sends the blood to the lungs to pick up more oxygen. This cycle repeats over and over again.

What Does the Circulatory System Do?

The circulatory system is made up of blood vessels that carry blood away from and towards the heart. Arteries carry blood away from the heart and veins carry blood back to the heart.

The circulatory system carries oxygen, nutrients, and

hormones to cells, and removes waste products, like carbon dioxide. These roadways travel in one direction only, to keep things going where they should.

What Are the Parts of the Heart?

The heart has four chambers - two on top and two on bottom:

The two bottom chambers are the right ventricle and theleft ventricle. These pump blood out of the heart. A wall called theinterventricular septum is between the two ventricles.

The two top chambers are the right atrium and the left atrium. They receive the blood entering the heart. A wall called theinteratrial septum is between the atria.

The atria are separated from the ventricles by the atrioventricular valves:

The tricuspid valve separates the right atrium from the right ventricle.

The mitral valve separates the left atrium from the left ventricle.

Two valves also separate the ventricles from the large blood vessels that carry blood leaving the heart:

The pulmonic valve is between the right ventricle and the pulmonary artery, which carries blood to the lungs.

The aortic valve is between the left ventricle and the aorta, which carries blood to the body.

What Are the Parts of the Circulatory System?

Two pathways come from the heart:

The pulmonary circulation is a short loop from the heart to the lungs and back again.

The systemic circulation carries blood from the heart to all the other parts of the body and back again.

In pulmonary circulation:

The pulmonary artery is a big artery that comes from the heart. It splits into two main branches, and brings blood from the heart to the lungs. At the lungs, the blood picks up oxygen and drops off carbon dioxide. The blood then returns to the heart through the pulmonary veins.

In systemic circulation:

Next, blood that returns to the heart has picked up lots of oxygen from the lungs. So it can now go out to the body. The aorta is a big artery that leaves the heart carrying this oxygenated blood. Branches off of the aorta send blood to the muscles of the heart itself, as well as all other parts of the body. Like a tree, the branches gets smaller and smaller as they get farther from the aorta.

At each body part, a network of tiny blood vessels calledcapillaries connects the very small artery branches to very small veins. The capillaries have very thin walls, and through them, nutrients and oxygen are delivered to the cells. Waste products are brought into the capillaries.

Capillaries then lead into small veins. Small veins lead to larger and larger veins as the blood approaches the heart. Valves in the veins keep blood flowing in the correct direction. Two large veins that lead into the heart are thesuperior vena cava and inferior vena cava. (The terms superior and inferior don't mean that one vein is better than the other, but that they're located above and below the heart.)

Once the blood is back in the heart, it needs to re-enter the pulmonary circulation and go back to the lungs to drop off the carbon dioxide and pick up more oxygen.

How Does the Heart Beat?

The heart gets messages from the body that tell it when to pump more or less blood depending on a person's needs. For example, when you're sleeping, it pumps just enough to provide for the lower amounts of oxygen needed by your body at rest. But when you're exercising, the heart pumps faster so that your muscles get more oxygen and can work harder.

How the heart beats is controlled by a system of electrical signals in the heart. The sinus (or sinoatrial) node is a small area of tissue in the wall of the right atrium. It sends out an electrical signal to start the contracting (pumping) of the heart muscle. This node is called the pacemaker of the heart because it sets the rate of the heartbeat and causes the rest of the heart to contract in its rhythm.

These electrical impulses make the atria contract first. Then the impulses travel down to the atrioventricular (or AV) node, which acts as a kind of relay station. From here, the electrical signal travels through the right and left ventricles, making them contract.

One complete heartbeat is made up of two phases:

1. The first phase is called systole (pronounced: SISS-tuh-lee). This is when the ventricles contract and pump blood into the aorta and pulmonary artery. During systole, the atrioventricular valves close, creating the first sound (the lub) of a heartbeat. When the atrioventricular valves close, it keeps the blood from going back up into the atria. During this time, the aortic and pulmonary valves are open to allow blood into the aorta and pulmonary artery. When the ventricles finish contracting, the aortic and pulmonary valves close to prevent blood from flowing back into the ventricles. These valves closing is what creates the second sound (the dub) of a heartbeat.

2. The second phase is called diastole (pronounced: die-AS-tuh-lee). This is when the atrioventricular valves open and the ventricles relax. This allows the ventricles to fill with blood from the atria, and get ready for the next heartbeat.

How Can I Help Keep My Heart Healthy?

To help keep your heart healthy:

Get plenty of exercise.

Eat a nutritious diet.

Reach and keep a healthy weight.

If you smoke, quit.

Go for regular medical checkups.

Tell the doctor about any family history of heart problems.

Let the doctor know if you have any chest pain, trouble breathing, or dizzy or fainting spells; or if you feel like your heart sometimes goes really fast or skips a beat.

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The heart is a pump, usually beating about 60 to 100 times per minute. With each heartbeat, the heart sends blood throughout our bodies, carrying oxygen to every cell. After delivering the oxygen, the blood returns to the heart. The heart then sends the blood to the lungs to pick up more oxygen.

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A blood vessel is a tube that carries blood in the circulatory system. Blood vessels that take blood away from the heart are arteries. Blood vessels that take blood back to the heart are veins. Capillaries are between veins and arteries and they supply tissue with blood.

The heart plus all of the blood vessels in the body together are called the circulatory system. Blood is moved by the pumping of the heart and carries oxygen to the tissues.

The expansion of blood vessels is called vasodilation, it helps the body to get rid of heat energy ( vas- in Latin means "container" or "vessel"). The constriction of blood vessels is called vasoconstriction, it prevents the body from losing warmth.

There are 100,000 km (60,000 miles) of blood vessels in an adult human body.

Growing new blood vessels is called angiogenesis.

Different parts of the body have different kinds of blood vessels for different parts of their work. The vessel wall consists of three shells:

inner - represented by the endothelium (single-layer squamous epithelium), which is built of elongated endothelial cells located on the basement membrane, and the subendothelial layer, which is based on loose fibrous connective tissue;

middle - consists of circular bundles of smooth muscle cells with layers of elastic fibers;

external - is represented by loose fibrous connective tissue, which contains a lot of blood vessels and nerve fibers.

The structure of the vessel wall depends on hemodynamic conditions: blood flow velocity, volume and blood pressure. Arteries located close to the heart are characterized by a predominance of elastic elements that are able to counteract high hemodynamic parameters. As you move away from the heart, hemodynamic values decrease, the caliber of blood vessels decreases and the number of muscle elements in their walls increases, which are able to create additional force to push blood into the network of the smallest vessels.

Images for kids

Transmission electron micrograph of a blood vessel displaying an erythrocyte (red blood cell, E) within its lumen, endothelial cells forming its tunica intima (inner layer), and pericytes forming its tunica adventitia (outer layer).

Constricted blood vessel.

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A blood vessel is a tube that carries blood in the circulatory system. Blood vessels that take blood away from the heart are arteries. Blood vessels that take blood back to the heart are veins. Capillaries are between veins and arteries and they supply tissue with blood.

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Read about the importance of the blood and its composition.

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Read about the importance of the blood and its composition.

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Humans can't live without blood. Without blood, the body's organs couldn't get the oxygen and nutrients they need to survive, we couldn't keep warm or cool off, fight infections, or get rid of our own waste products. Without enough blood, we'd weaken and die.

Here are the basics about the life-sustaining fluid called blood.

What Is Blood and What Does It Do?

Blood brings oxygen and nutrients to all the parts of the body so they can keep working. Blood carries carbon dioxide and other waste materials to the lungs, kidneys, and digestive system to be removed from the body. Blood also fights infections, and carries hormones around the body.

Blood is made up of blood cells and plasma. Plasma (pronounced: PLAZ-muh) is a yellowish fluid that has nutrients, proteins, hormones, and waste products. The different types of blood cells have different jobs.

What Are the Types of Blood Cells?

Red blood cells: Red blood cells (RBCs, also called erythrocytes; pronounced: ih-RITH-ruh-sytes) are shaped like slightly indented, flattened disks. RBCs contain hemoglobin (pronounced: HEE-muh-glow-bin), a protein that carries oxygen. Blood gets its bright red color when hemoglobin picks up oxygen in the lungs. As the blood travels through the body, the hemoglobin releases oxygen to the different body parts.

Each RBC lives for about 4 months. Each day, the body makes new RBCs to replace those that die or are lost from the body. RBCs are made in the inside part of bones called the bone marrow.

White blood cells: White blood cells (also called leukocytes; pronounced: LOO-kuh-sytes) are a key part of the immune system. The immune system helps the body defend itself against infection. Different types of white blood cells (WBCs) fight germs, such as

bacteria and viruses . Some types of WBCs make antibodies, which are special proteins that recognize foreign materials and help the body get rid of them.

There are several types of WBCs, and their life spans vary from hours to years. New cells are constantly being formed - some in the bone marrow and some in other parts of the body such as the spleen, thymus, and lymph nodes.

Blood contains far fewer WBCs than red blood cells, although the body can increase WBC production to fight infection. The white blood cell count (the number of cells in a given amount of blood) in someone with an infection often is higher than usual because more WBCs are being made or are entering the bloodstream to battle the infection.

Platelets: Platelets (also called thrombocytes; pronounced: THROM-buh-sytes) are tiny oval-shaped cells that help in the clotting process. When a blood vessel breaks, platelets gather in the area and help seal off the leak. Platelets work with proteins called clotting factors to control bleeding inside our bodies and on our skin.

Platelets survive only about 9 days in the bloodstream and are constantly being replaced by new platelets made by the bone marrow.

How Does Blood Travel in the Body?

With each heartbeat, the heart pumps blood throughout our bodies, carrying oxygen to every cell. After delivering the oxygen, the blood returns to the heart. The heart then sends the blood to the lungs to pick up more oxygen. This cycle repeats over and over again.

The circulatory system is made up of blood vessels that carry blood away from and toward the heart.

Two types of blood vessels carry blood throughout our bodies:

1. Arteries carry oxygenated blood (blood that has gotten oxygen from the lungs) from the heart to the rest of the body.

2. Blood then travels through veins back to the heart and lungs, so it can get more oxygen to send back to the body via the arteries.

As the heart beats, you can feel blood traveling through the body at pulse points - like the neck and the wrist - where large, blood-filled arteries run close to the surface of the skin.

What if Someone Has Low Numbers of Blood Cells?

Sometimes medicine can be given to help a person make more blood cells. And sometimes blood cells and some of the special proteins blood contains can be replaced by giving a person blood from someone else. This is called a blood transfusion (pronounced: trans-FEW-zyun).

People can get transfusions the part of blood they need, such as platelets, RBCs, or a clotting factor. When someone donates blood, the whole blood can be separated into its different parts to be used in these ways.

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Humans can't live without blood. Without blood, the body's organs couldn't get the oxygen and nutrients they need to survive, we couldn't keep warm or cool off, fight infections, or get rid of our own waste products. Without enough blood, we'd weaken and die. Here are the basics about the life-sustaining fluid called blood.

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(Image credit: Ross Toro, Livescience contributor)

The circulatory system consists of three independent systems that work together: the heart (cardiovascular), lungs (pulmonary), and arteries, veins, coronary and portal vessels (systemic). The system is responsible for the flow of blood, nutrients, oxygen and other gases, and as well as hormones to and from cells.

An average adult has 5 to 6 quarts (4.7 to 5.6 liters) of blood, which is made up of plasma, red blood cells, white blood cells and platelets.

The heart is a muscular organ with four chambers. Located just behind and slightly left of the breastbone, it pumps blood through the network of arteries and veins called the cardiovas- cular system.

The systemic circulation is a major portion of the circulatory system. The network of veins, arteries and blood vessels transports oxygenated blood from the heart, delivers oxygen and nutrients to the body's cells and then returns deoxygenated blood back to the heart.

The system of blood vessels in the human body measure about 60,000 miles (96,560 kilometers).

Arteries carry oxygen-rich blood from the heart through the body. Veins carry oxygen-poor blood back to the heart.

The superior vena cava carries oxygen-poor blood into the heart. The aorta carries oxygenated blood from the heart to organs and tissues.

Related:

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Diagram of the Human Circulatory System (Infographic)

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(Image credit: Ross Toro, Livescience contributor) The circulatory system consists of three independent systems that work together: the heart (cardiovascular), lungs (pulmonary), and arteries, veins, coronary and portal vessels (systemic). The system is responsible for the flow of blood, nutrients, oxygen and other gases, and as well as hormones to and from cells.

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Blood transfusions are a lifesaving treatment for many Americans. Blood transfusions are needed for many reasons, including surgery, after accidents, and for patients with

chronic illnesses and cancer.

Blood cannot be artificially made, so doctors rely on volunteer donations. To keep the blood supply safe, every donation is tested for blood type and checked for infectious diseases.

What Are the Components of Blood?

All blood contains the same basic components:

But not everyone has the same blood type.

What Are the Blood Types?

Categorizing blood according to type helps prevent reactions when someone gets a blood transfusion. Red blood cells have markers on their surface that characterize the cell type. These markers (also called antigens) are proteins and sugars that our bodies use to identify the blood cells as belonging in us.

The two main blood groups are ABO and Rh.

The ABO blood system has four main types:

Type A: This blood type has a marker known as A.

Type B: This blood type has a marker known as B.

Type AB: This blood type has both A and B markers.

Type O: This blood type has neither A or B markers.

Blood is further classified as being either "Rh positive" (meaning it has Rh factor) or "Rh negative" (without Rh factor).

So, there are eight possible blood types:

1. O negative. This blood type doesn't have A or B markers, and it doesn't have Rh factor.

2. O positive. This blood type doesn't have A or B markers, but it does have Rh factor. O positive blood is one of the two most common blood types (the other being A positive).

3. A negative. This blood type has A marker only.

4. A positive. This blood type has A marker and Rh factor, but not B marker. Along with O positive, it's one of the two most common blood types.

5. B negative. This blood type has B marker only.

6. B positive. This blood type has B marker and Rh factor, but not A marker.

7. AB negative. This blood type has A and B markers, but not Rh factor.

8. AB positive. This blood type has all three types of markers - A, B, and Rh factor.

Having any of these markers (or none of them) doesn't make a person's blood any healthier or stronger. It's just a genetic difference, like having green eyes instead of blue or straight hair instead of curly.

Why Are Blood Types Important?

The immune system is the body's protection against invaders. It can identify antigens as self or nonself. To get a blood transfusion safely, a person's immune system must recognize the donor cells as a match to his or her own cells. If a match isn't recognized, the cells are rejected.

The immune system makes proteins called antibodies that act as protectors if foreign cells enter the body. Depending on which blood type you have, your immune system will make antibodies to react against other blood types.

If a patient gets the wrong blood type, the antibodies immediately set out to destroy the invading cells. This aggressive, whole-body response can give someone a fever, chills, and low blood pressure. It can even cause vital body systems - like breathing or the kidneys - to fail.

Here's an example of how the blood type-antibody process works:

Let's say you have type A blood. Because your blood contains the A marker, it makes B antibodies.

If B markers (found in type B or type AB blood) enter your body, your type A immune system gets fired up against them.

This means that you can only get a transfusion from someone with A or O blood, not from someone with B or AB blood.

In the same way, if you have the B marker, your body makes A antibodies. So as a person with type B blood, you could get a transfusion from someone with B or O blood, but not A or AB.

Things are a little different for people with type AB or type O blood:

If you have both A and B markers on the surface of your cells (type AB blood), your body does not need to fight the presence of either.

This means that someone with AB blood can get a transfusion from someone with A, B, AB, or O blood.

But if you have type O blood, your red blood cells have neither A or B markers. So:

Your body will have both A and B antibodies and will therefore feel the need to defend itself against A, B, and AB blood.

A person with O blood can only get a transfusion with O blood.

Can Teens Donate Blood?

Blood transfusions are one of the most frequent lifesaving procedures hospitals do. Every 2 seconds someone needs a blood transfusion. So there's always a need for blood donors. One blood donation can save up to three lives.

About 15% of blood donors are high school and college students. If you'd like to help, contact your community blood center. It's one way to be an everyday superhero and save lives!

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Blood transfusions are a lifesaving treatment for many Americans. Blood transfusions are needed for many reasons, including surgery, after accidents, and for patients with chronic illnesses and cancer. Blood cannot be artificially made, so doctors rely on volunteer donations. To keep the blood supply safe, every donation is tested for blood type and checked for infectious diseases.

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In living donation, the following blood types are compatible: Donors with blood type A... can donate to recipients with blood types A and AB Donors with blood type B... can donate to recipients with blood types B and AB Donors with blood type AB...

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Giving blood, a gesture that saves lives. Find out more about blood donation.

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Learn more about the parts of the circulatory system with this interactive webpage.

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Learn more about the parts of the circulatory system with this interactive webpage.

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eHarcourtSchool.com has been retired and is no longer accessible. Because of the age of this application, the programs supported by this platform are not able to benefit from the technological improvements in accessibility, security, and HMTL5 (non-Flash) that we have incorporated into our newer programs and platforms in recent years.
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eHarcourtSchool.com has been retired and is no longer accessible. Because of the age of this application, the programs supported by this platform are not able to benefit from the technological improvements in accessibility, security, and HMTL5 (non-Flash) that we have incorporated into our newer programs and platforms in recent years.

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Learn about the blood vessels with this interactive page.

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Learn about the blood vessels with this interactive page.

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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Blood is a liquid in humans and many animals except insects. Blood is pushed through the organism by the heart, and brings nutrients and oxygen to our tissues. It also takes away waste and carbon dioxide from tissues.

Blood of vertebrates is made up of blood plasma and various cells - red blood cells, white blood cells and platelets. Platelets help blood to clot. Hemoglobin is in red blood cells. White blood cells help fight infections and heal wounds.

Blood plasma is the yellow liquid in which blood cells float. Plasma is made up of nutrients, electrolytes ( salts), gases, non-protein hormones, waste, lipids, and proteins. These proteins are albumin, antibodies (also called immunoglobulins), clotting factors, and protein hormones. Plasma that does not have the protein fibrinogen is called serum and cannot clot. Adults have about 3 liters of plasma. Plasma is a liquid, mostly water (90%). Plasma takes up 55% of volume.

Red blood cells

Another name for red blood cell is erythrocyte. 'Erythro' means red; 'cyte' means cell. RBC is an acronym for red blood c ells.

RBCs carry oxygen and carbon dioxide around our body. Cells in our body need oxygen to live. Cells also make carbon dioxide as a waste. RBCs bring oxygen into the body and carbon dioxide out.

RBCs are filled with haemoglobin. This is a protein. It is made to carry a large amount of oxygen. Haemoglobin has iron in it. The iron and oxygen gives haemoglobin its red color. This is why blood is red. Erythropoietin promotes the creation of RBCs. Blood type antigens are carried on the surface of red cells.

RBCs also help the blood stay normal pH. The blood needs a to be at a pH of 7.4. If it is much more or less than 7.4 a person can get very sick or die. RBCs are a buffer for the blood pH. Buffer means that it stops changes in pH. The proteins and the carbon dioxide in the RBC are buffers for the blood. If you do not have enough RBCs, you will die.

White blood cells

White blood cells are a big part of the immune system. They attack things that do not belong in the body. They kill germs such as bacteria and viruses. They kill cancer cells. White blood cells also help to fight other toxic substances.

White blood cells find where the germs are, and start to destroy them. WBCs arrive in the blood. They also go out of the blood in places where there is infection. WBCs do this to fight the germs that make the infection. If they go out of the blood to fight an infection, they may return in the lymphatic system. So WBCs are in lymph nodes.

Another name for white blood cell is leukocyte. Leuko means white, cyte means cell. WBC is an acronym for white blood cell. There are three main kinds of WBCs. They are lymphocytes, granulocytes and monocytes. Some of the WBCs mature into cells which do similar work in the tissues.

The different WBCs work in different ways. Some WBCs kill and eat germs and cancer cells. Some WBCs make antibodies that mark a cell so other WBCs will kill it. Some WBCs make chemicals. They release these chemicals to fight things that do not belong in the body. These chemicals cause inflammation in a part of the body. When a germ makes someone sick, the body shows it. If a bacteria gets under someone's skin and causes an infection, the skin gets red, hot, and painful. This redness, heat, and pain are signs of inflammation. This shows that WBCs are fighting the infection and killing the bacteria.

Platelets help make blood clot. A clot is when the liquid blood becomes solid. The body makes blood clot when the skin is cut. This stops blood from going out of the skin too much.

For blood to be able to clot is essential. But, rarely, some blood clots are bad. If a blood clot happens in a blood vessel going to the brain, it can cause a stroke. If it happens in a blood vessel going to the heart, it can cause a heart attack. This does not usually happen to young, healthy people.

Platelets are not the only things that make clots. There are proteins in the blood that help make clots. Both platelets and clotting proteins are needed to make good clots.

Where does blood come from?

Blood is mesodermal in origin. Blood cells are made in the bone marrow and in the spleen. The bone marrow is the soft material in the middle of bones. Special cells in the bone marrow make most of the blood cells in your body.

Plasma proteins are made mostly by the liver. The water and electrolytes in plasma come from the food and water that you eat.

Although blood is a fluid, in some respects it is a kind of connective tissue. Its cells originate in bone marrow and the spleen, and in the blood there are potential molecular fibres in the form of fibrinogen. These are activated when a blood clot forms.

Images for kids

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Blood is a liquid in humans and many animals except insects. Blood is pushed through the organism by the heart, and brings nutrients and oxygen to our tissues. It also takes away waste and carbon dioxide from tissues. Blood of vertebrates is made up of blood plasma and various cells - red blood cells, white blood cells and platelets.

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Learn more about the blood's composition with this interactive page.

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Learn more about the blood's composition with this interactive page.

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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Watch this video about the different blood vessels.

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Watch this video about the different blood vessels.

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Fun Kids - the UK's children's radio station

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It needs to get oxygen and nutrients from the top to the bottom of your body and it manages this with the help of the body's circulatory system.

The body has a network of blood vessels that carry blood around.

The way it works is quite similar to how traffic runs on the roads.

To keep traffic running smoothly, all the traffic travelling in the same direction will travel on the same part of the road and the same goes for blood vessels. Arteries travel in one direction, veins in the other.
What are arteries?
Arteries are the large vessels that carry blood through the heart, around to every part of your body.

The blood that arteries carry from the lungs is full of oxygen.

As they get closer to the surface or into smaller spaces, blood is transferred into microscopic vessels called capilliaries.

When the blood has released its oxygen, it returns back to the lungs and heart through veins.
What are veins?
If you could see the blood in your veins, it would look a lot darker than it was in your arteries.

The movement of the blood through the heart and around the body is called circulation - and your heart is really good at this.

Did you know?

It takes less than 60 seconds to pump blood to every cell in your body!

A cool thing is, it doesn't matter if you're standing on your head or jumping on a trampoline, blood keeps pumping - all the way around the body.

Clever doors called valves make sure that the blood can't go the wrong way. Blood has to travel in one direction only.
Why are valves so important?
Well, if there's a problem with them, it can make you feel very poorly.

Think of them like doors. Sometimes the valves don't open enough to allow the blood to flow.

This is called stenosis and the heart has to work harder to push blood through.

A different type of problem can occur when the valves don't shut properly.

When the valves don't close properly, blood can leak backwards.

This is called regurgitation and your heart has to work harder to push it the right way.

They'll be finding out all about the cool stuff that goes on inside your heart and how it manages to pump blood around your body all the time - even when you're asleep!

You can listen to Professor Hallux on:

Professor Hallux's Heart Beat funding thanks to a Heart Research UK healthy heart grant!

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Veins, Arteries and Capillaries - Fun Kids - the UK's children's radio station

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It needs to get oxygen and nutrients from the top to the bottom of your body and it manages this with the help of the body's circulatory system. The body has a network of blood vessels that carry blood around. The way it works is quite similar to how traffic runs on the roads.

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Read about how to improve the blood circulation.

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Read about how to improve the blood circulation.

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Do you often find yourself a victim of chest pain, shortness of breath, or headaches? Are you perhaps considered at high risk for a heart attack? Follow these tips to improve your blood circulation throughout your body and lower your risk...

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Foods that help you improve your blood circulation.

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Foods that help you improve your blood circulation.

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Foods that help to improve your circulation | Revitive

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Take a look at these 10 Super foods that are thought to help improve blood circulation.

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Kids learn about the cardiovascular system including blood, the heart, and blood vessels. The science of the human body's energy delivery system.

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The heart is a muscle in the body. The heart is divided into four parts. These parts are called chambers.

The job of each chamber is to pump blood to the organs of the body. The chambers of the heart are hollow so they can fill up with blood as it passes through each one.

This means the heart does not weigh very much, but without the heart, the body cannot live.

The four chambers or compartments of the heart are Left Ventricle, Right Ventricle, Left Atrium, Right Atrium.

Like the other organs in your body, your heart grows with the rest of your body. The heart is always about the size of your fist. This means that when you were born, your heart was about the size of your tiny baby fist, and will stop growing when you do.

There are two different kinds of 'tubes' coming off the heart that carry the blood from the heart to every part of the body. The two types of tubes are called veins and arteries.

Arteries carry blood away from the heart and veins bring blood back to the heart. This process is called circulation.

Circulation starts in the left ventricle of the t. The blood is pumped from there into the aorta, which is the largest artery in the human body. When it enters the aorta, the blood is filled with oxygen. The oxygen in the blood goes to every part of the body. Blood also carries hormones and other important nutrients and disease-fighting cells throughout the body.

While the blood is spreading oxygen and all those other things through the body, it is also picking up things we don't need-things like carbon dioxide. When the blood has gotten rid of the oxygen and other important things, it comes back to the heart-going into the right atrium. From there, the blood goes into the right ventricle. The right ventricle has an important job. It sends the blood into the lungs so it can be refueled with more oxygen. When this has happened, the lungs send the blood to the left atrium and the whole process starts all over again.

How long does it take for the blood to travel through the body?

It takes about 20 seconds for blood to travel throughout the body. That is pretty amazing because if you stretched out all the veins, arteries, capillaries, and vessels the blood travels through, you would have a 'rope' 60,000 miles long! That's long enough to circle the earth...twice!!!

But wait! Your heart beats more than every 20 seconds, so what's up with that?

report this ad It takes 20 seconds for blood to travel throughout your body. But your heart beats faster and more often than every 20 seconds because not all your blood goes through your body at one time. This means your heart is always pumping blood.

Have you ever noticed that sometimes your heart beats faster than it does at other times? Why is that?

How fast does your heartbeat

Here is what you need:

Yourself

Pen and paper

The help of an adult

Stopwatch, timer with seconds, or a clock with a second hand

Get familiar with checking your heart rate

To check your heart rate put your first two fingers over just below your jaw; pressing GENTLY and feeling for the spot where you can feel your pulse. If you are having trouble, ask a parent to help you.

Once you are confident you can check your pulse (heart rate) or have someone to do it for you, continue with the remaining steps in this experiment.

Standing still, take your heart rate and write down the number of beats per minute

Run in place for one minute, stop, take your heart rate and write down the number of beats per minute

Lay down for one minute, take your heart rate and write down the number of beats per minute

Walk around your house at a normal pace for one minute, take your heart rate and write down the number of beats per minute

Look at the results-when did your heartbeat the fastest

When did it beat the slowest

What was your highest heart rate?

What was your slowest heart rate?

The faster your body moves the more oxygen it takes for your body to function. This means your blood has to work harder and faster to get your body the oxygen it needs. So...to get it there faster, the heart has to pump faster-just like a car speeds up when you give it more gas.

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Heart Rate Experiment (Explained!) - Science for Kids

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The heart is a muscle in the body. The heart is divided into four parts. These parts are called chambers. The job of each chamber is to pump blood to the organs of the body. The chambers of the heart are hollow so they can fill up with blood as it passes through each one.

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Systemic circulations and pulmonary circulation

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Systemic circulations and pulmonary circulation

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Pulmonary & Systemic Circulation | Circulatory Anatomy

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Read about Pulmonary Circulation and Systemic Circulation: The Routes and Function of Blood Flow

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Watch the video about the systemic and pulmonary circulation.

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Watch the video about the systemic and pulmonary circulation.

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Circulatory system working with other systems!

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Circulatory system working with other systems!

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Nervous System:The nervous system is made up of the brain, spinal cord and nerves.The brain sends messages to the heart telling it to beat.The heart beat pumps blood throughout the body so that nutrients and oxygen can be brought to cells and waste can be removed.

Digestive System: The digestive system breaks down foods and takes out needed nutrients.These nutrients are put into the blood stream for the cells to use as energy.Minerals and vitamins are also put into the blood stream to strengthen bones and the immune system.

Muscular System: The heart is a muscle.The expanding and contracting of this muscle is what pumps blood throughout the body.

Respiratory System:The respiratory system is how oxygen is brought into the body.It enters through the lungs into the alveoli.From there it is sent through blood vessels into the blood stream for the body to use.At the same time, carbon dioxide is brought to the lungs through the blood to be exhaled.

Skeletal System:Marrow inside of bones produces red and white blood cells.These blood cells are parts of the blood stream and are responsible for carrying oxygen and fighting off disease.

Endocrine System:The endocrine system is where hormones are produces.Hormones and other chemicals produced by these glands use the circulatory system to travel to needed parts of the body.Example:Adrenaline, created by the Adrenal gland, travels through the blood stream to the heart causing an increased heart rate.

Immune System:The immune system is made up of white blood cells and antibodies.These things travel inside the blood so that they can be transported to the site of infection/invasion to remove and/or hopefully destroy it.This is how you fight off sickness.

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Circulatory System Working With Other Systems! - Delta Science

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Nervous System:The nervous system is made up of the brain, spinal cord and nerves.The brain sends messages to the heart telling it to beat.The heart beat pumps blood throughout the body so that nutrients and oxygen can be brought to cells and waste can be removed.