456 
RESPIRATION AND EXCRETION 
Fainting. — Fainting is due to an insufficient supply of 
blood in the brain. This lack of blood may arise from 
several causes, but the most common is some disturbance 
of the digestive processes, which causes the heart to beat 
too slowly. A fainting person should be placed flat on 
his back, if possible, with his head slightly lower than the 
rest of his body, and should be given plenty of fresh air. 
A dash of cold water in the face, or a bottle of ammonia 
held to the nostrils, is often helpful in restoring consciousness. 
The Effect of Drugs and Alcohol. — “ The flow of the 
blood is modified by various drugs, some causing the blood 
to flow more rapidly, others more slowly. Coffee causes 
Figure 406. — Superficial Lymphatics of Arm and Hand. 
the heart to beat harder and at the same time causes some 
of the arteries to become smaller. For this reason it is 
called a stimulant.” — Conn and Buddington. 
It has been stated frequently that alcohol increases the 
activity of the heart. Careful experiment, however, shows 
that not only is the effect not that of a stimulant, but that 
when used in large amounts, it markedly weakens the action 
of the heart. If taken only in small amounts, the heart 
sometimes shows a slight increase in its rate of beating, 
but this occurs only when the brain becomes excited, and if 
the person is kept quiet no change in the heart beat is notice¬ 
able. Thus the primary action is on the brain. 
“ A second effect of alcohol is more evident. The small 
blood vessels in the skin are enlarged. This produces a 
