232 TYPE OF RESPIRATION. 



the movement upon a plate attached to a vibrating tuning-fork. The 

 inspiration (ascending limb) begins with moderate rapidity, is accelerated 

 in the middle, and towards the end again becomes slower. The expira- 

 tion also begins with moderate rapidity, is then accelerated, and becomes 

 much slower at the latter part, so that the curve falls very gradually. 



Inspiration is slightly shorter than expiration. According to Sibson, 

 the ratio for an adult is as 6 to 7 ; in women, children, and old people, 

 6 to 8 or 6 to 9. Vierordt found the ratio to be 10 to 14'1 (to 24'1); 

 J. R. Ewald, 11 to 12. It is only occasionally that cases occur where 

 inspiration and expiration are equally long, or where expiration is 

 shorter than inspiration. When respiration proceeds quietly and 

 regularly, there is usually no pause (complete rest of the chest-walls) 

 between the inspiration and expiration (Eiegel). The very flat part of 

 the expiratory curve has been wrongly regarded as due to a pause. 

 Of course, we may make a voluntary pause between two respirations, 

 or at any part of a respiratory act. 



Some observers, however, have described a pause as occurring between the end 

 of expiration and the beginning of the next inspiration (expiration pause), and also 

 another pause at the end of inspiration (inspiration pause). The latter is always 

 of very short duration, and considerably shorter than the former. 



During very deep and slow respiration, there is usually an expiration pause, 

 while it is almost invariably absent during rapid breathing. An inspiration pause 

 is always absent under normal circumstances, but it may occur under pathological 

 conditions. 



In certain parts of the respiratory curve slight irregularities may appear, which 

 are sometimes due to vibrations communicated to the thoracic walls by vigorous 

 heart-beats (Fig. 104). 



The "type" of respiration may be ascertained by taking curves from 

 various parts of the respiratory movements. Hutchinson showed that 

 in the female, the thorax is dilated chiefly by raising the sternum and 

 the ribs (Respiratio costalis), while in man it is caused chiefly by a 

 descent of the diaphragm (Respiratio diaphragmatica or abdominalis). 

 In the former, there is the so-called " costal type" in the latter the 

 " abdominal or diaphragmatic type" 



Forced Respiration. This difference in the type of respiration in the sexes 

 occurs only during normal quiet respiration. During deep and forced respiration, 

 in both sexes the dilatation of the chest is caused chiefly by raising the chest and 

 the ribs. In man, the epigastrium may be pulled in sooner than it is protruded. 

 During sleep, the type of respiration in both sexes is thoracic, while at the same 

 time the inspiratory dilatation of the chest precedes the elevation of the abdominal 

 wall (Mosso). 



It is not determined whether the costal type of respiration in the female depends 

 upon the constriction of the chest by corsets or other causes (Sibson), or whether 

 it is a natural adaptation to the child-bearing function in women (Hutchinson). 

 Some observers maintain that the difference of type is quite distinct, even in sleep, 

 when all constrictions are removed, and that similar differences are noticeable in 

 young children. This is denied by others, while a third class of observers hold 



