216 A TEXTBOOK OF PHYSIOLOGY 



is modified by the pressure of application of the sphygmograph and 

 by instrumental errors. The pulse may be recorded by allowing an 

 artery to spurt upon a moving paper (Fig. 118). 



As already said, the pulse wave occurs later, the farther the place 

 of observation is from the heart. This is well seen in Fig. 119. 



We have no scale by which we can measure the blood-pressure 

 in sphygmograph tracings. 



When the arterioles are dilated, or when the capillaries are only 

 filled at each systole, the pulse may pass through the arterioles and 



reach the capillaries, as may be seen in 

 the pink of the nail when the arm is 

 held above the head in cases of aortic 

 regurgitation. 



The normal average pulse-rate is 



tjj 72 per minute, in woman about 80. 



Tall men usually have a slower rate than 

 short men. Individual variations from 

 40 to 100 have been observed consistent 

 with health. Napoleon, a short man, 

 had a pulse-rate of 40. In the new-born, 

 the pulse beats on the average 130 to 

 140 times a minute ; in a one-year-old 

 child, 120 to 130; three years, 110; ten 

 years, 90; fifteen years, 80 to 85. Active 

 muscular exercise may increase the pulse- 

 rate to 130. Nervous excitement, extreme 

 debility, and rise of body temperature, 

 also increase it markedly. The pulse is 

 more frequent when one stands than 

 when one sits or lies down. In 100 young 

 FIG. 118. H.EMAUTOGRA:M. men o f twenty-seven years the average 

 (Landois and Stirling.) was : 78-9 standing, 70-1 sitting, 66-6 lying. 



In states of debility this difference be- 

 tween horizontal and erect postures may increase to 30 to 50 per 

 minute. The taking of food, especially hot food, increases the 

 frequency; so does smoking cigarettes. 



The average pulse-rates for different ages is given in the following, 

 table : 



Age, Pulse-Rate, 



in Years. per Minute. 



Foetus . . 135-140 



0-1 134 



1-2 117 



3-4 108 



5-9 98 



9-10 91 



12-13 88 



16-17 80 



Mca 72 



Women 80 



