What work does the heart do?

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Man has been studying the inside of the body for the past 2000 years. But they came to know what the heart did only at the beginning of the 17th centuary. That is when the English physician William Harvey described the circulation of the blood.
Much earlier than that, the heart had been carefully dessected and sescribed, yet no one knew its use.
The heart is a very efficient pump that moves blood through the body. The heart is a muscle that contracts and relaxes about seventy times a minute, for all the minutes of all the years of your life.
Each contraction and relaxation of the heart muscle is a heartbeat. You have more than 100,000 heartbeats every day. Each heartbeat pumps about two ounces of blood. This results in about 13,000 litres of blood being pumped each day.