Heart القلب وعمله - آلة صغيرة وعظيمة

HEART

Did you give your friends valentines and little heart-shaped candies on Valentine's Day? Do you ever cross your heart when making a promise that you really, really mean? Or turn on the radio to hear a guy singing about his broken heart?

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 [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط], and that the brain tells the heart what to do. So what's the heart up to, then? How does it keep busy? What does it look like? Let's find out

Working That Muscle
Your heart is really a [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]. 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 the waste that your body has to get rid of.

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.
We Got the Beat
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. Every day, an adult heart pumps 2,000 gallons (7,500 liters) worth of blood by filling and contracting - and sending the blood around and around again. The heart is one hard worker!

Heart Parts
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 atr ia (say: ay-tree-ah, but if you're only talking about one, then say atrium). The atria are the chambers that fill with the blood returning to the heart from the body and lungs.
The two chambers on the bottom are called the ventricles (say: ven-trih-kulz). 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. While the ventricles pump blood out of the heart, 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, and they let blood flow from the atria to the ventricles. The other two are called the aortic (say: ay-or-tic) 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.
It's Great to Circulate
The movement of the blood through the heart and around the body is called circulation (say: sir-kyoo-lay-shun), and your heart is really good at it. It's so good at it that it only takes about 20 seconds to pump blood to every cell in your body. That's less time than you need to sing Take Me Out to the Ballgame! Your body needs this steady supply of blood to keep it working right. It also needs the blood to get rid of waste that would make your body sick if it stuck around.
The left side of your heart sends blood to the body. This blood has lots of oxygen in it, and the oxygen is one of the things that your cells need to stay alive. The body takes the oxygen out of the blood and uses it in your body's cells. The cells say thanks by using the oxygen, making carbon dioxide and other stuff it needs to get rid of, and dumping the carbon dioxide and wastes back into the blood to be carried away. The blood has done the first part of its job by delivering the oxygen to the cells, and now it's time for it to pick up the trash (the carbon dioxide and other waste).
Each time the blood circulates from the heart out to the body, about 20% (one fifth) of it goes through the [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط] where some of the waste is taken out, and then the blood heads back to the heart. The right side of the heart is ready for the hand off: It takes the blood to the lungs for a little freshening up. The carbon dioxide leaves the blood by getting breathed out by the lungs, and the oxygen gets into the blood from the air we breathed in. Now the blood has got the oxygen it needs to go back to the left side of the heart and start all over. And remember, it all happens in less than half a minute!
Blood Gets Around
The heart needs helpers to make sure the blood moves all over, so it works with blood vessels. The heart is attached to these blood vessels, which are like pipes that carry the blood around the body. The blood vessels that carry blood away from the heart (the fresh blood that's full of oxygen) are called [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط], and the ones that carry blood back to the heart are called [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]. There are many veins and arteries all throughout your body.

Listen to the Lub-Dub
When you go for a checkup, your doctor uses a [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط] to listen carefully to your heart. A healthy heart makes a lub-dub sound with each beat. This sound comes from the valves opening and shutting on the blood inside the heart. The first sound (the lub) happens when the blood hits the mitral and tricuspid valves between the atria and ventricles. The next sound (the dub) happens when the blood hits the aortic and pulmonic valves that close up after the blood has been squeezed out of the heart and as the heart relaxes to fill with blood for the next beat. 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 by feeling 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. Just like you need to exercise your leg and arm muscles, you need to exercise your heart, too. Aerobic [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط], like walking, running, and swimming, is a great way to keep your heart in shape. Try to be active every day!
Eating a variety of healthy foods is great for your heart. Avoiding a lot of high-fat foods will help keep your heart happy, too.
Stay away from smoking! [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط] is bad for every part of your body, and especially your heart. Your heart and blood vessels hate cigarettes because smoking makes their jobs much harder and can damage them.

So now you know that your heart doesn't look like a valentine, but it sure is an amazing body part. It started pumping blood before you were born, and will continue pumping throughout your whole life. So take good care of your heart and it will take good care of you!

Nice very good job
May Allah bless u & ur parents

O! Allah protect us from every evil