7O APPLIED PHYSIOLOGY 



The heart is the most regular and the best behaved 

 organ in the body, but alcohol makes it beat faster and 

 harder than the body needs. So it tires itself out, and 

 soon its beats become weaker. Thus a strong man weak- 

 ens his heart instead of making it stronger. The cells of 

 the heart's muscle, like the rest of the cells of the body, 

 do not get proper food, and so they become still weaker. 

 Alcohol gives a feeling of great strength to the body, but 

 this is due to weakness of the brain, which does not feel 

 fatigue as it should. 



132. Tobacco. Tobacco weakens and poisons all the 

 cells of the body, but it affects the heart more than any 

 other part. It causes the heart to beat more rapidly, and 

 at the same time with less strength. Sometimes the heart 

 beats slower than it should for a little while, and then 

 becomes rapid again. Sometimes its beat can be too 

 plainly felt. The result is that the smoker cannot work 

 so hard as he once could. His heart beats with violence, 

 but drives the blood with little force. He becomes very 

 short of breath, because the blood does not circulate in 

 the lungs as it should. When a young person's heart is 

 injured by tobacco, there is great danger that it will stay 

 weak all through life. Athletes, when training for a con- 

 test like running or rowing, do not smoke or chew, for 

 they know that to do so would weaken their hearts and 

 make them short-winded. 



SUMMARY 



1. The blood is a clear liquid containing albumin and 



minerals. In it there float many red cells and fewer 

 white cells. 



2. Tubes called arteries carry blood to all parts of the 



' body. 



