CIRCULATION AND THE BLOOD SYSTEM 



XLIV. — Properties and Location of Arteries and 



Veins. 



Apparatus. — A watch with a second hand, a needle, a chemical 

 thermometer. 



Directions. — Examine the back of the hand and wrist 

 and locate the dark-colored veins. Is the blood this color? 

 Place your finger on a vein. Can you feel any motion? Is 

 there any difference in the size and prominence of the veins 

 when you exercise violently? Why should you expect this 

 result? 



Find your pulse on the palm side of the wrist. Coimt its 

 beats and record the number per minute. Test this rate at 

 various times of the day. Is it uniform at all times? Test 

 your body temperature at the same time by placing the bulb 

 of the chemical thermometer under the tongue. Does the 

 temperature vary with the pulse rate? Does either increase 

 after violent exercise? If food is burned up by exercise, and 

 blood contains oxygen and food, how do you account for 

 these effects? 



Examine other parts of the body for veins and arteries 

 (pulse always indicates the presence of an artery). Which 

 are most numerous on the surface? Which are best pro- 

 tected? The bleeding of a cut artery is much more difficult 

 to stop than that of a vein, owing to its pulsation. 



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