File:A text-book on physiology - for the use of schools and colleges - being an abridgment of the author's larger work on human physiology (1866) (14581730047).jpg

Identifier: textbookonphysio00drap (find matches)
Title: A text-book on physiology : for the use of schools and colleges : being an abridgment of the author's larger work on human physiology
Year: 1866 (1860s)
Authors: Draper, John William, 1811-1882
Subjects: Human physiology Physiology
Publisher: New York : Harper & Bros.
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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he action of the diaphragm is insufficientfor the introduction of air, and a still farther volume isobtained by raising the ribs, which increases the dimen-sions of the chest from right to left, and also from frontto back. In men, this effect takes place more particu-larly through the movements of the lower ribs, and thisform of respiration is therefore sometimes called the in-ferior-costal; but in women the upper ribs are moremovable, the dilatation of the chest is there greater, andthe respiration therefore designated as the superior-cos-tal. In these movements of the ribs, and especially inviolent respiration, many muscles are involved. In the reverse act, that is, in expiration, or the expul-sion of air through the trachea, the floor of the chest israised. The diaphragm, when it contracted, made press- What does Fig. 67 illustrate ? In deep respiration, what more isdone? What difference is there between the respiration of men andwomen? How is the expulsion of the air accomplished?
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MOVEMENTS OF RESPIRATION. 149 m*e upon the viscera of the abdomen, and forced themuscular walls of that cavity outward; but, as soon asthe diaphragm relaxes, the abdominal muscles contract,and thus an antagonizing force is originated tending toexpel the air. In this the elasticity of the lungs and ofthe walls of the thorax itself affords a great assistance.Owing to this elasticity, the muscular exertion requiredfor the introduction of the air greatly exceeds that re-quired for its expulsion. In tranquil respiration, we may regard the changingof the air to be accomplished by the alternate depres-sion and elevation of the diaphragmatic floor of thechest. On an average, this takes place 17 times in aminute, and in an adult of the standard size we may as-sume that 17 cubic inches of air are introduced at eachinspiration. One breath in five is usually deeper thanthe other four. The statement often made, that fivepulsations correspond to one respiration, must be re-ceived with a certain res

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