School Hygiene - Brossura

Brossura

ISBN 10: 0217044522 ISBN 13: 9780217044523

Riassunto

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913. Excerpt: ... CHAPTER X THE NEED OF PURE AIR Life and Oxygen.--There can be no life without oxygen, and animals get their supply of it from the air. Air is a mixture of several gases, chief among which are nitrogen, oxygen, and carbon dioxide. All animals breathe: some through lungs, as man, others through gills, as fishes, and some through tubelike openings in their bodies, as grasshoppers. The higher animals breathe mainly through their lungs, though the skin in most of them has some power of transpiration. Cut off from a supply of oxygen, man quickly dies, because the vital processes cannot proceed unless the tissues are constantly bathed in this essential element. We must not think, therefore, that the oxygen in the air goes no farther than the lungs, for these are only the sources from which the blood gathers its supply, and from them carries it to every fiber and tissue of the body. Each action of the body, whether voluntary or involuntary, requires oxygen, and hence each tissue must be supplied if it is to live and to carry on its functions. Fifteen to sixteen times every minute, as you do the ordinary work of the day, the lungs are expanded through the pressure of the air, when the diaphragm is pulled down and the ribs elevated by the muscles for these purposes. Equally often, of course, as these muscles relax and thereby reduce the capacity of the chest, the air is driven out of the lungs. This process has not stopped since the first breath, and will not until death. It must go on during sleep as well as during waking hours, for the body is ever hungry for oxygen. One can consciously increase or decrease this rate for a short time, but fortunately it goes on in the main unconsciously. Death would ensue immediately if all the oxygen were removed from the body a...

Su questa edizione

• ISBN 10: 0217044522
• ISBN 13: 9780217044523
• Rilegatura: Copertina flessibile