3 2 7 



LABORATORY EXPERIMENTS IN RESPIRATION. 



1. Respiratory Rate in Man. Count your respirations for from 2 

 to 4 minutes while sitting quietly, and determine the average number per 

 minute. Repeat the counting after standing for 5 minutes, and after 

 brisk exercise. These determinations involve the element of conscious- 

 ness, under which condition it is difficult for a person to breathe with his 

 normal rate and depth. 



Make a series of determinations of respiratory 

 rates of persons who are sitting quietly but uncon- 

 scious of your determinations. Count the rates in 

 a number of persons of different ages; where possible, 

 take into consideration height, weight, etc. Tabu- 

 late the results for a comparison and for future 

 reference. 



2. The Character of Respiratory Movements 

 in Man. A number of instruments have been 

 devised for measuring human respiratory move- 

 ment, many of which measure the change in 

 diameter of the chest in respiratory movement. 

 Adjust one of these, for example Burdon-Sander- 

 son's stethograph, to the thorax, and record the 

 movement of the receiving tambour on a smoked- 



paper kymograph which travels at the rate of i 



, m, . , j FIG. 244. Change in 



cm. per second. Inis record, called a stethogram, Diameter of the Body in 



will exhibit the respiratory rate, the relative time of Respiration, Costal Type. 

 ^, >. , , , ^, a. Outline of the body in 



the linspiratory and expiratory phases, and the forced expiration. In the 



character of each. heavy continuous line, b, 



3. The Actual Change of Diameter in the Chest 

 in Respiration. Use a caliper provided for the pur- ordinary inspiration and 



, i , ,. f , the inner margin that of 



pose and measure the dorso- ventral diameter of the ordinary expiration. c t 



chest at a series of points along the sternum, taking Contour of forced inspira- 

 j. J _ 1 , . , ^ ,. Al . , tion. (After Hutchinson.) 



the reading at the height of the inspiratory phase 



and of the expiratory phase in ordinary respiration. Repeat the measure- 

 ment in forced respiration. Map the results on millimeter paper, as 

 indicated in figure 244. 



Repeat these measurements in the transverse diameter at the first, 

 fifth, and tenth ribs. 



Using the thoracograph, figure 245, record the outline of the cross 

 section of the chest at the level of the mammae, tenth rib, and the umbili- 

 cus, showing the volume changes in the following four positions: (i) 

 Ordinary expiration, (2) ordinary inspiration, (3) forced expiration, (4) 

 forced inspiration, see figure 246. 



