File:Physiology, hygiene and sanitation, an elementary textbook of physiology, with special attention given to hygiene and sanitation (1919) (14578459940).jpg

Identifier: physiologyhygien00heiz (find matches)
Title: Physiology, hygiene and sanitation, an elementary textbook of physiology, with special attention given to hygiene and sanitation
Year: 1919 (1910s)
Authors: Heizer, W. L. (W. Lucien), b. 1880
Subjects: Physiology Hygiene Sanitation
Publisher: Louisville, Ky., C.T. Dearing Printing Co., Incorporated
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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The outer walls of the lungs lie in close contact withthe inner walls of the thoracic cavity. The layers ofpleura are, therefore, in contact and as the walls move toand fro, in breathing, the layers of pleura rub over oneanother. Nature pro-vides a fluid to pre-vent friction and ir-ritation of the pleura. If an infection ofthe pleura occur,such an inflamma-tion resulting is call-ed pleurisy, and isexceedingly painful,because, with eachrespiration, the sen-sitive nerves are rubbed together. How We Breathe. Force all of the air out of the lungsand hold your breath until you are forced to breathe.Notice what happens. The walls of the chest are raised andspread out; the back is straightened; the nostrils are openeda little wider, and something seems to swell up inside. The muscles between and overlying the ribs, raise thedrooping ribs. A broad muscle, arched across the lower out-let of the thorax (diaghragm), is made to contract whichpushes the stomach and bowels downward and this further
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A B Fig*. 74.—A. The chest in expiration. B.The chest in inspiration. Note its in-creased capacity. 172 PHYSIOLOGY, HYGIENE AND SANITATION increases the space in the thorax. The lungs are made tofollow the walls of the thorax, as more space is thus created,and the air rushes through the nostrils into the lungsexactly as it does into a bottle when the cork is suddenlypulled. Now after drawing a full breath, hold it until you areforced to let go. Notice what happens. The chest wallsfall, the stomach and bowels seem to rise, the shoulders andback relax a little. The lungs which, when full of air were on the stretch like a piece of elastic rubber, now contractand the air comes rushing out of the nostrils, with a slightbreezy sound. This is the act of expiration. The Capacity of the Lungs. One wonders how much airthe lungs will hold. In ordinary, quiet breathing onlyabout thirty cubic inches of air pass into the lungs. In aforced respiration about one-hundred and thirty cubicinches of ai

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