HYGIENE OF THE CIRCULATORY SYSTEM 169 



blood vessels, causing them to lose their ability of contracting and 

 relaxing. Tobacco is likely to cause palpitation of the heart. 

 Both alcohol and tobacco seemingly interfere with good physique. 

 For that reason, part of an athlete's training is abstinence from 

 them. Good health habits exclude alcohol, tobacco, and drugs. 



QUESTIONS AND SUGGESTIONS 



1. How was it possible for early scientists to study the circulatory 

 system scientifically? 



2. What three erroneous ideas in regard to circulation were ex- 

 ploded through the scientific method ? 



3. Draw a diagram of a liver cell, a lymphatic, and a capillary. By 

 means of labeled arrows, indicate the possible exchanges of materials. 



4. In what cells in the body can blood leave an unusual supply of 

 (a) calcium, (6) fat, (c) worn-out red corpuscles, (d) protein for destruc- 

 tion ? Where can it collect (a) oxygen, (6) urea, (c) white corpuscles, 

 (d) glucose? 



5. What is the relation of the lymph system to the blood system ? 



6. What rules of health should be followed if the organs of circu- 

 lation are to be kept in the best possible condition ? 



7. In terms of circulation, discuss a possible cause of each of the 

 following diseases : anaemia, varicose veins, and hardening of the 

 arteries. 



SUPPLEMENTARY READINGS 



Haggard, H. W., The Science of Health and Disease (Harper & Bros.). 

 Kimber, D. C., and Gray, C. E. Textbook of Anatomy and Physiology (The 

 Macmillan Co.). 



WH. FTTZ. AD. BIO. 12 



