CHAPTEE Y. 



FREQUENCY OF THE HEART'S ACTION. 



Frequency of the heart's action Influence of age Influence of digestion Influ- 

 ence of posture and muscular exertion Influence of exercise Influence of 

 temperature Influence of respiration on the action of the heart Cause of 

 the rhythmical contractions of the heart Influence of the nervous system on 

 the heart Division of the pneumogastrics Galvanization of the pneumogas- 

 trics Causes of the arrest of action of the heart Blows upon the epigas- 

 trium. 



Frequency of the Hearts Action. Physicians have al- 

 ways attached the greatest importance to the frequency of 

 the action of the heart, as one of the great indications of the 

 general condition of the system. The variations which are 

 met with in health, dependent upon age, sex, muscular activ- 

 ity, the condition of the digestive system, etc., point to the 

 fact that the action of the heart is closely allied to the various 

 functions of the economy, and readily sympathizes with their 

 derangements. As each ventricular systole is followed by 

 an expansion of the arteries which is readily appreciated by 

 the touch, it is more convenient to study the succession of 

 these movements by exploring the vessels, than by examina- 

 tion of the heart itself. Leaving out certain of the qualities 

 of the pulse, this becomes an exact criterion of the acts of the 

 heart. 



The number of pulsations of the heart is not far from 

 seventy per minute in an adult male, and from six to ten 



