68 



HUMAN PHYSIOLOGY 



contracts it sends blood below into its corresponding 

 ventricle. As each ventricle contracts, the blood is 

 sent out in the one case (left) to the body, in the 

 other case (right) to the lungs. Having regard to 

 these actions there dawns upon our minds the 



5 



V- 7 



3. I 



Fig. 20. SECTION OF HUMAN HEART (right side). 



(7) wall of right ventricle ; (2) left ventricle ; (3) right 

 auricle ; (4} appendix ; (5 and 6) great veins opening 

 into auricle ; (7) aorta ; (8) pulmonary artery leading 

 to lungs showing valves (10) ; (P) cords of the tricuspid 

 valve between auricle and ventricle. 



necessity for some contrivance by way of preventing 

 any reflux or back-flow of the blood in the wrong 

 direction. When each ventricle contracts to send 

 blood to the lungs or body, so much of the blood if not 



