Дословно почти перевести the heart is simply a pump, which circulates blood throughout the body. tubes called blood vessels carry it from the heart to all parts of the body and back again. this round trip is known as the circulation. vessels carrying blood away from the heart are known as arteries and those returning blood to the heart are known are known as veins. the heart pumps blood round the body about 70 times a minute in adults. the heartbeats can be felt as the pulse where certain arteries lie just beneath the skin, and the most well – known place where this occurs is at the wrist. the heart lies in the chest immediately behind the breast bone. it consists of two chambers, left and right, separated from each other by a wall. each chamber is further divided into upper and lower compartments, which communicate with each by valves. each upper compartment is called an atrium and each lower a ventricle. note that there is no communication at all between the left and right sides of the heart. heart failure, or cardiac arrest, means that the heart has stopped beating. this of course, means that no blood is being pumped round the body and death occurs in a few minutes. but as the heart is just a simple pump, it can be made to beat artificially by rhythmically applying pressure to the chest. this squeezes the heart between the breast bone and forces blood out the heart into the circulation. when pressure on the chest has been relaxed, blood returns to the heart again.