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EXPERIMENTAL PHYSIOLOGY 



cate also the chordce tendince that attach this valve to the pap- 

 illary muscles on the surface of the heart. What is the effect 

 of the contraction of the ventricle on the action of this valve? 



Ao 



FIG. 37. Left Auricle and Ventricle (Sheep): a, b, c, bristle seekers showing con- 

 nections of auricle with ventricle, of auricle with veins, and of ventricle with arter- 

 ies; PV, pulmonary veins; pp, papillary muscles; mv, mitral valve; PA, pulmonary 

 artery; Ao, aorta; SVC, superior vena cava. 



Note finally the semilunar valves at the entrance to the pul- 

 monary artery. How does their arrangement prevent the 

 backward flow of blood into the heart? 



E. Cut off the front walls of the left auricle and ventricle 

 in the same way, Have they any connection with the right 



