CHAPTER VIII. 

 RESPIRATION. 



I. RESPIRATORY MOVEMENTS IN MAN. 



1. Direct Observation. Let one of the students of a labora- 

 tory group, preferably one of slender build, strip to the waist. 

 Let him sit straight on a stool with the arms and hands symmetri- 

 cally placed at the sides, and both sides of the chest evenly illumi- 

 nated. 



(a) Observe first whether or no the two sides of the chest are of 

 equal size and the respiratory movements equally prominent on 

 the two sides. Note the increase in the lateral and antero-posterior 

 diameters of the thorax in inspiration. Note the movements of 

 the abdominal wall in inspiration and in expiration. Note the 

 changes in the intercostal spaces during the respiratory movements. 



What muscles seem to be involved in quiet inspiration ? in 

 quiet expiration ? In which part of the thorax is the lateral diame- 

 ter enlarged most, during quiet inspiration ? What are the move- 

 ments of the ribs during expiration and inspiration ? Demonstrate 

 these movements on the skeleton thorax. 



Remembering the attachments of the external and internal in- 

 tercostal muscles, demonstrate their action on the skeleton thorax 

 by the use of heavy elastic bands attached to the ribs in the same 

 way as the intercostals are attached. 



(b) Now let the subject of the observation make a forced in- 

 spiration, followed by a forced expiration. Compare this with the 

 movements of quiet respiration. What additional muscles are in- 

 volved in inspiration ? in expiration ? 



(c) By means of some form of pneumograph or stethograph 

 record the respiratory movements. This may be conveniently 



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