CHAPTER IV 

 RESPIRATORY MOVEMENTS 



Physiological anatomy of the respiratory organs Movements of respiration Action of the 

 diaphragm Action of the muscles which raise the ribs Scalene muscles Intercostal 

 muscles Levatores costarum Auxiliary muscles of inspiration Expiration Influence 

 of the elasticity of the pulmonary structure and walls of the chest Action of muscles 

 in expiration Internal intercostals Infracostales Triangularis sterni Obliquus ex- 

 ternus Obliquus internus Types of respiration Frequency of the respiratory move- 

 ments Respiratory sdunds Coughing, sneezing, sighing, yawning, laughing, sobbing 

 and hiccough Quantity of air changed in the respiratory acts Diffusion of air in the 

 lungs. ^\J 



THE tide of air in the lungs does not strictly constitute respiration, 

 these organs serving merely to facilitate the introduction of oxygen 

 into the blood and the exhalation of carbon dioxide. When the system 

 is drained of blood or if the blood is rendered incapable of interchanging 

 its gases with the air, respiration ceases and all the phenomena of as- 

 phyxia are presented, although air may be introduced into the lungs 

 with perfect regularity. As in the nutrition of tissue the nitrogenous 

 constituents of the blood, united with inorganic substances, are transformed 

 into the tissue itself, finally changed into excrementitious products, such 

 as the urinary matters, and discharged from the body, so the oxygen of 

 the blood is appropriated, and carbon dioxide, which is an excrementi- 

 tious substance, is produced and is discharged in the expired air. 



The essential conditions for respiration in animals that have a circu- 

 lating nutritive liquid are air and blood separated by a membrane that 

 will allow the passage of gases. The effete products of respiration 

 contained in the blood, the most important of which is carbon dioxide, 

 pass out and vitiate the air. The air is deprived of a certain proportion 

 of its oxygen, which passes into the blood, to be conveyed to the tissues. 

 Thus the air must be changed to supply fresh oxygen and get rid of car- 

 bon dioxide. 



PHYSIOLOGICAL ANATOMY OF THE RESPIRATORY ORGANS 



Passing from the mouth to the pharynx, two openings are observed ; 

 a posterior opening, which leads to the oesophagus, and anteriorly the 

 opening of the larynx, which is the beginning of the passages concerned 

 exclusively in respiration. 



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