Control of Circulation. 77 



respiration, muscle action, brain action, etc. Hence the 

 effects on each of these processes will be taken up in the 

 separate chapters. 



Effect of Alcohol on the Heart. The effect of alcohol 

 on the heart is through the nervous system, which controls 

 the heart. The heart is held in check all the time by the 

 action of the vagus nerves. Alcohol more or less paralyzes 

 these nerves, so they can no longer restrain the heart. 

 Hence it at once begins to beat too rapidly. The heart is 

 like a horse that always wants to run away. Just as soon 

 as the brake is taken off it jumps into a run. A team of 

 vicious horses may be held in so long as the driver retains 

 his seat and his strength. But if the driver falls from his 

 seat, they immediately plunge into a wild gallop. Alcohol 

 paralyzes the restraining driver of the heart and arteries, 

 and they at once run wild. 



Summary. i. Circulation is controlled by the nervous system. 



2. This control is involuntary. 



3. The sympathetic nervous system consists of two rows of ganglions 

 in the body cavity along each side of the spinal cord. 



4. The sympathetic system regulates the size of the arteries, and by 

 this means regulates the amount of blood going to any organ. 



5. The heart may be made to beat faster through the sympathetic 

 nervous system. This may come through reflex action and be caused 

 by emotions. 



6. The heart may be made to beat slower through the vagus nerves. 



7. Alcohol may cause the arteries of the face to dilate and thus make 

 the face become red. 



8. Alcohol often makes the heart beat faster; but soon it beats more 

 slowly than before alcohol was taken. 



Questions. i . Why do the feet easily get cold while studying ? 



2. What makes the hands grow red and puff up after snowballing ? 



3. Why does light exercise before retiring make one sleep better ? 



4. How does the application of ice, or cold water, relieve headache ? 



5. Why should the clothing be changed after getting wet ? 



