Protecting your heart / Metropolitan Life Insurance Company.

Date:
[1940?]
Catalogue details

Licence: Public Domain Mark

Credit: Protecting your heart / Metropolitan Life Insurance Company. Source: Wellcome Collection.

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    The Healthy Heart and How It Works |e a single living cell in the body can exist for more than a few minutes without oxygen. Every cell must have food and water. Every cell produces wastes which must be removed. Most of the cells of the body are fixed in one place. They cannot move about to obtain supplies of oxygen, food, and water and to get rid of wastes. Everything they need must be carried to them; everything they must get rid of must be carried away from them. The blood is the great common carrier of the body, and the heart is the pump which keeps the blood moving in a steady stream through an intricate system of blood vessels to. keep the body alive. Blood is forced through the blood vessels by the con- ’ of the heart. After each contraction the heart has a split second of rest before it beats again. During the rest period after each beat, blood flows into the heart through inlet valves. As the heart tightens on its contents at the next contraction, the inlet valves close, preventing a back flow, and the outlet valves open. Through these open valves the blood is driven out of the heart into the arteries which distribute it to all parts of the body. The arteries have relatively thick elastic walls which stretch to accommodate each fresh load of blood driven out by the heartbeat. In the rest period between beats the stretched elastic walls recoil and thus help to press the blood continuously onward. By the term “‘blood pressure’’ is meant the pressure exerted by the blood on the walls of the arteries. | tractions or ‘“‘beats’
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