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A TEXTBOOK OF PHYSIOLOGY 



animals. Cheyne-Stokes breathing is a type of breathing characterized 

 by a waxing and waning of the depth of the respiratory movements 

 (Fig. 167). Starting from a state of apncea, the respirations gradually 



FIG. 165. CAT, VAGI INTACT. FIG. 166. SAME CAT AS FIG. 165. 



(F. H. Scott.) VAGI DIVIDED. (F. H. Scott.) 



Upper tracing, thoracic respiration re- 

 corded by means of tambours; lower 

 tracing, carotid blood-pressure. Period 

 of insufflation of lungs shown by rise 

 in line of respiratory tracing. 



become more and more marked, reaching a maximum where the depth 

 is considerably deeper than normal, and then gradually decline again, 

 and cease, to be followed by another period of activity. This type of 

 breathing occurs clinically in cases with defective circulation, renal 



UIIIHIIIINJIIIIMMM1 



FlG. 167. CHEYXErSTOKES RESPIRATION. 



disease, etc., and is due to oxygen-want in the respiratory centre, which 

 causes it to act in a periodic manner. Oxygen -want causes a hyperpncea 

 which reduces the alveolar percentage of C0 2 . Apncea then results 



