96 



ADVANCED LESSONS IN PRACTICAL PHYSIOLOGY 



impulse with a blue pencil. Observe the changes in its conspicuousness 

 when the position of the subject is changed and during inspiration and 

 expiration. Explain the results. If the impulse is not in its normal 

 place, ascertain the direction and degree of its displacement. Give its 

 probable cause. Palpate the radial artery and note the interval of time 

 between the radial pulse and the cardiac impulse. Palpate the carotid 

 artery low in the neck. Note that the difference in time between this 



FIG. 59. CARDIOGRAPH. 



The tape is strapped around the chest. The central button is applied to the "apex- 

 beat" and its pressure on the chest wall regulated by means of the three screws at the 

 sides. The tube at the upper part of the instrument serves to connect the drum of the 

 cardiograph with a registering tambour. (Sanderson.) 



pulse and the cardiac impulse is much less, a result easily explicable 

 upon the ground of distance. 



Adjust a cardiograph to the area of the cardiac impulse. Connect 

 it with a recording tambour and allow the latter to register its excursions 

 upon the smoked paper of a kymograph revolving at a moderate speed. 

 This record should be made above a time-curve, registered by a Jaquet 

 chronograph. 



.Tec 



FIG. 60. CARDIOGRAM. 

 AB, Systole; BC, plateau; CD, diastole; DA, pause; time in seconds. 



Explain the character of the cardiogram so obtained. Excepting 

 the cardiac rate, is it possible to derive valuable data from this curve 

 which more particularly pertain to the quality of the contractions of 

 the heart? Give reasons for your conclusions. 



Annotation. The method of palpating the radial artery is practised as follows: 

 With your left hand support the right hand of the subject in a position of slight 

 extension. As a rule, the right artery gives better results. Place the second and 



