x CIRCULATION OF THE BLOOD 137 



of the radial artery at the wrist, the temporal artery 

 just in front of the ear, and the carotid on either side 

 of the larynx can be easily felt. 



104. Alcohol and Tobacco. Alcohol acts upon the 

 blood, the arteries, and the heart itself. It impov- 

 erishes the blood by acting upon the corpuscles, thus 

 decreasing its capacity for carrying oxygen. The 

 effect upon the blood vessels is to dilate them. For 

 this reason the skin looks flushed and red ; the capil- 

 laries become enlarged ; and the person feels warm 

 while the body is really giving off a large amount of 

 heat, which must lower the temperature of the body. 

 It is said that deposits of fat are made in the walls of 

 the arteries and of the heart, thus weakening and pre- 

 disposing them to disease. 



The nerves controlling the heart and arteries are 

 paralyzed by alcohol. The heart now acts like a run- 

 away horse, beating very rapidly and attempting to fill 

 the much distended blood vessels. 



The nicotine of tobacco acts as a poison on the 

 nerves of the heart. This is probably its most harmful 

 effect upon the body. The heart beat becomes irregu- 

 lar and less vigorous. The nerves are no longer as 

 delicate and sensitive as they should be. The smoker's 

 heart goes on beating at nearly the same rate day and 

 night, thus robbing the heart of a certain amount of 

 rest that is necessary to keep it in a perfectly healthy 

 condition. It is believed by scientists that many of the 

 cases of fatal heart disease may be traced to the use of 

 tobacco. 



