140 



Life and Health 



The pipes leading from it and gradually growing smaller 

 and smaller are the arteries. 



The very minute vessels into which they lead at last 

 are capillaries. 



The pipes which convey the blood back to the heart are 

 the veins. 



211. The Heart. The heart is a pear-shaped, muscular 



organ, roughly esti- 

 mated as about the size 

 of the closed fist of the 

 person to whom it be- 

 longs. It lies in the 

 chest behind the breast- 

 bone and is lodged 

 between the lobes of 

 the lungs, which partly 

 cover it. 



In health the apex of 

 the heart beats against 

 the chest wall between 

 the fifth and sixth ribs, 

 about an inch and a 

 half to the left of the 

 middle line of the body. 

 The beating of the 



FIG. 69. Anterior View of the Heart. heart can be readily 



A, superior vena cava ; B, right auricle ; C, right felt, heard, and often 

 ventricle; D t left ventricle ; E, left auricle; seen moving the chest 



_ 

 Wall as it Strikes 



aSclinst it 



^212. The Pericar- 

 dium. The heart is enclosed in a bell-shaped covering, 

 called the pericardium. This is really double, with two 



F, pulmonary vein ; //, pulmonary artery ; 

 K, aorta ; L, right subclavian artery ; M, right 

 common carotid artery; JV, left common ca- 



