The Heart and Its Function (Classic Reprint) - Softcover

Down, John Langdon

Softcover

ISBN 10: 1334513910 ISBN 13: 9781334513916

Verlag: Forgotten Books, 2018

Inhaltsangabe

Excerpt from The Heart and Its Function

Notwithstanding the many millions of years which our world and race have, according to some, already existed, the discovery of the circulation of the blood is but a thing of yesterday. From some passages in his work, De Trinitatis Erroribus, published in 1531, Servetus would seem to have been fully aware of the lesser or pulmo nary circulation. But it was not till 1628 that the doctrine of the circulation of the blood through the system generally was actually published by Dr. William Harvey, though indeed he 'had taught it publicly from the year 1619. It was not, however, till 1661, more than thirty years subsequently, that the Circulation of the blood was actually demonstrated by means of the micro scope, by Malpighi, so that this important fact has been known for little more than two centuries.

The whole quantity of blood in the body has been reckoned at about one-fourteenth part of the weight of the body; the blood in the body of a man weighing fourteen stone will therefore amount to one stone, or fourteen pounds. If we accept this as a probable average of the weight of blood in the body, then as fourteen pounds amount to 224 ounces, and as the left ventricle contains, as we suppose, only 3 ounces, it follows that the whole blood of a man weighing 196 lbs. Passes through his left ventricle in nearly 75 (74-6) Of its systoles or contractions. And as we suppose the heart to contract only 70 times in a minute, then the whole of the blood of such a man passes through his heart 48 times in one hour, or 1152 times in one day. Of course the length of time that the whole of the blood in a man takes to pass through his heart depends upon three factors, - first, the actual amount of blood he possesses; second, the size of his ventricular cavity; and thirdly, the rate of its pulsation.

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Details zur Ausgabe

• Verlag: Forgotten Books
• Erscheinungsdatum: 2018
• Sprache: Englisch
• ISBN 10: 1334513910
• ISBN 13: 9781334513916
• Einband: Tapa blanda
• Anzahl der Seiten: 112
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