CONTROL OF PERIPHERAL CIRCULATION 
lO- 
— ^ NORMAL FOREARM 
e — ^ DEEP NERVES BLOCKED 
- 
i^- - 
_W!"-^ 
i 
25 
SO 
Minutes 
FAINTING. 9 NORMAL 6BLOCKED 
Figure 3. Changes in blood flow in the normal and nerve- 
blocked forearm during fainting. Fainting occurred at the time 
indicated by the vertical dashed line. (After Barcroft and Edholm, 
J. Physiol. (Lond.). 104:161. 1945). 
5 lO 
MINUTES 
Figure 4. Changes in forearm blood flow during emotional 
stress. At the beginning of rectangle A, the subject, who was a 
medical student, was told thathe would be given an oral examination 
in physiology within a few minutes. During rectangle B, he was 
given an oral examination. During rectangle C, personal remarks 
were made about an acquaintance of the subject. Though he showed 
no outward signs of emotion, forearm blood flow increased consid- 
erably. 
119 
