3. 79.
Your heart is sometimes called the engine or the motor in your body and sometimes called the pump. It works away, both day and night. First it pumps out some blood, rests for a few seconds, and then it pumps some more. In a normal day, the heart pumps about 2,500 gallons of blood from the auricles and ventricles.
4. 79.
By using a stethoscope to listen to the heart, the doctor can tell whether your heart is beating evenly and whether the valves are closing tightly. The stethoscope makes these sounds so clear that the doctor can hear them easily. The stethoscope has an earpiece that he places on your chest and tubes that he places in his ear. The earpiece carries the sound or your heart's beating along the tubes to the doctor's ears, and it makes the sound seem much louder than it really is. The doctor could listen to your heartbeat by pulling his ear against your chest.
5. 79.
An easy experiment can help you understand what happens when the heart beats. You can do this experiment with a hollow rubber ball. Make a small hole in it, and fill the ball with water through the hole. When you squeeze the ball, you will notice how the water comes out in a spurt each time you squeeze. After each spurt the ball comes back to its round shape again. Something like this happens when your heart beats. The muscles in your heart grow smaller, or contract, and squeeze the blood out of the heart. Each time this happens, we say your heart is beating. Perhaps you have noticed that the doctor places his finger on the pulse in your wrist when you are ill. By doing this he can tell how fast your heart is beating.
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