252 



HUMAN PHYSIOLOGY 



Such a condition is well seen after violent muscular exertion, 

 and in certain fevers. In these conditions the dicrotic wave 

 is so well marked that it can be readily perceived with the 

 finger. It is to this form of pulse that the term dicrotic is 

 applied in medicine. 



On the other hand, if the ventricles are acting slowly and 

 feebly in relationship to the arterial pressure, the initial 

 outflow of blood does not take place so rapidly and com- 

 pletely (Fig. 121, 

 continuous line), 

 and the initial 

 rise in the pulse 

 is thus not so 

 rapid. The re- 

 sidual outflow of 

 blood is more 

 marked and 

 causes a well- 

 marked secon- 

 A5 vs. V-<>- ~'~ p d ar y rise in the 



FIG. 121. Diagram to show the effect of altering the pulse Curve the 



relationship between the activity of the Heart and predicrotic Wave. 



the arterial blood pressure. - - b is the y pp r f J n rflqfts 



curve of intra-ventricular pressure, and b l is 



a pulse curve with an active heart and a relatively this may be 



low arterial pressure. a and a 1 are the same hjcrher than the 

 with a sluggish heart and a relatively high arterial 



pressure. primary crest, 



producing the 



condition known as the anacrotic pulse. The relatively 

 high intra-arterial pressure here prevents the development 

 of a well-marked dicrotic wave. 



In extreme cases of this kind, when the arterial walls are 

 very tense, they may recover after their expansion in an 

 irregular jerky manner, and may give rise to a series of kata- 

 crotic crests producing a polycrotic pulse (Fig. 120, 3). 



From what has been said it will be seen that a study of 

 the pulse wave gives most valuable information as regards 

 the state of the circulation, and the physician constantly 

 makes use of the pulse in diagnosis. 



Palpation of Pulse. On placing the finger on the radial 

 artery the points to determine are 



