190 BIOLOGY AND HUMAN LIFE 



The veins and arteries are also subject to special disorders. 

 Varicose veins are those in which the walls and valves have 

 deteriorated, resulting in obstructions to the ready flow of blood 

 toward the heart at these points. They are related to over- 

 strain, and particularly to standing a great deal without suffi- 

 cient exercise. Laundry workers and motormen show large 

 numbers of cases, whereas letter carriers and others who walk 

 about a great deal rarely suffer from this disorder. Hardening 

 of the arteries is a more serious condition. It may be due to va- 

 rious infectious diseases, to alcohol, to overwork, and to malnu- 

 trition. In this condition the arteries lose their elasticity and so 

 interfere seriously with the circulation of the blood ; and they 

 are more easily burst by a sudden increase in blood pressure. 



158. Care of the heart. Every contraction of the ventricles 

 sends a wave of pressure through the blood in the arteries. The 

 muscular and elastic walls of the arteries ^^give" somewhat to 

 this pressure, and this is the pulse which can be felt in any 

 artery near the surface of the body, as at the wrist, on the tem- 

 ples, or directly in front of the ear. From the character of the 

 pulse the physician can often tell a great deal about the work- 

 ings of the heart and about the condition of the blood vessels. 

 The pulse may be regular or irregular ; it may be strong or weak. 



A strong heartbeat would ordinarily increase the pressure 

 of the blood inside the arteries ; but if the arteries are flabby, 

 the additional work of the heart may fail to distribute the 

 blood properly to all parts of the body. Cold feet and hands 

 are an indication of inadequate circulation, but the cause of this 

 condition may be in the heart or it may be in the blood vessels. 



In examining a person the careful physician, athletic direc- 

 tor, or insurance examiner will always listen to the beating of 

 the heart and examine the pulse and test the blood pressure. 

 From the sounds of the heart he can tell whether there is a 

 defect in any of the valves. A leaky heart has to do a great 

 deal more pumping to keep the body supplied than a sound 

 heart, since a portion of every stroke is wasted in pumping 

 blood that goes back into the auricles. 



