HEART AND BLOOD
Your heart is a muscle.
It works like a pump.
It sends blood around inside your body.
Blood takes good things to parts of your body.
It takes away waste.
The heart is a muscle inside a person’s chest. Your heart is about the size of your fist. It pumps blood so that the blood moves to every part of the body. Blood is red and watery and helps keep people well. Blood keeps moving all through your body all the time.
Blood goes out of the heart in tubes called arteries (say ah-ter-reez). The blood takes oxygen and nutrients to all parts of the body and takes away waste. It goes back to the lungs through tubes called veins (say vanes). The lungs put air back into the blood, before it goes to the heart again to be pumped out through the arteries and round the body again.
Sections of the Heart
The human heart consists of four sections, called chambers. There are two on each side of the heart, two on top and two underneath. On top there is a left atrium and a right atrium (say ay-tree-um). The two together are called atria (ay-tree-uh). These fill with blood that is returning from the body and lungs. Underneath the atria are the left and right ventricles. They pump out the blood to go to the body and lungs. The left and right sides of the heart are separated by a thick wall of muscle called a septum.
Pulse and Blood Pressure
Before each beat, the heart fills with blood. Then the muscle squeezes and pushes the blood out. Your heart does this constantly. You can feel your heart beating. It is called a pulse. A doctor or nurse feels your pulse on your wrist, but it can be felt at other places too. Your heart beats about 100 000 times each day.
Sometimes a doctor or nurse needs to check that a person’s heart is beating strongly and at the right speed. This is called blood pressure.
A machine measures the person’s blood pressure.
If a person is hurt and loses a lot of blood, they need more blood to be put inside their body. Extra blood is kept at a Blood Bank. People go there and nurses take some of their blood. The blood is kept in special bags for times when it is needed. There are different types of blood. Most people have the blood called A or O.
The heart beats around 3 billion times in the averages person’s life.
About 8 million blood cells die in the human body every second, and the same number are born each second.
Within a tiny droplet of blood, there are some 5 million red blood cells.
It takes about 20 seconds for a red blood cell to circle the whole body.
Red blood cells make approximately 250,000 round trips of the body before returning to the bone marrow, where they were born, to die.
Red blood cells may live for about 4 months circulating throughout the body, feeding the 60 trillion other body cell.