ADVANCED EXPERIMENTAL PHYSIOLOGY 



169 



The velocity can also be measured in the artificial schema by 

 injecting 1 c.c. of methylene blue sat. sol. into artery, and noting 

 by means of a stop-watch (or electric signal and drum) the moment 

 of injection, and the moment when the blue fluid reaches the 

 capillary tube. 



The Circulation Time. In the artificial schema measure the 

 circulation time by injecting methylene blue into the vein V, and 

 noting how long the blue takes to reach 

 the venous end of the capillary tube. 



The Work of the Heart. To estimate 

 the work of the heart in the artificial schema 

 the mean pressure H, and velocity in the 

 aorta V, and the volume of the systolic 

 output Q, must be obtained. 



FIG. 171. Cybulski's photo- 

 haeinatochometer. A cannula 

 shaped as shown is introduced 

 into the blood-vessel. The os- 

 cillations of the mercury -menisci 

 are photographed. 



M = the mass of the output in grammes = Q 

 multiplied by the specific gravity of the 

 blood. 



Close the clip on the arteriole tube and 

 start the pump. Note the mean pressure 

 H indicated by the manometer M. 



To obtain V inject into the artery, at 1 

 metre from the capillary tube, 1 c.c. of sat. 



<snl rnpfVivlpviP Vilno A cirlo fiiKu ic r^rr* 



KM. rnethylene blue. A side tune is pro- 



virlprl fnr tlio rmrrv-keo rvf rnaL-iurr tViic iiiipn 



viaert lor the purpose ol making this injec- 



tioii. Note with a stop-watch, or by an 



electric signal and drum, the time between the injection and the 



appearance of the blue at the beginning of the capillary tube. 



Having obtained V, the output can be reckoned if the sectional 

 area (a) of the aorta be obtained and the time (t) of a cardiac 

 cycle. Measure the diameter of the artery. Half this and obtain 

 the radius. 



a = 7T? >2 .* 



Count the number of pulses per minute, and by dividing the number 

 found by 60 obtain t. Then Q = ad. 



Now calculate the work of the pump from the data obtained. 

 The work spent in maintaining velocity is almost negligible in 

 comparison with that spent in overcoming resistance. 



In man the output may be taken as 60 grms., the average aortic 



