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HUMAN PHYSIOLOGY. 



on the right side and the aorta on the 

 left side by way of the right side of the 

 heart, the cardio-pulmonary vessels and 

 the left side of the heart. 



The venous blood flowing towards 

 the heart is emptied by the superior 

 and inferior venae cavas into the right 

 auricle from which it passes through 

 the auriculoventricular opening into the 

 right ventricle; thence into and through 

 the pulmonary artery and its branches 

 to the pulmonary capillaries where it is 

 arterialized, i.e., yields up a portion of 

 its carbon dioxid and takes on a fresh 

 supply of oxygen and is changed in 

 color from bluish- red to scarlet-red. 

 The arterialized blood flowing towards 

 the heart is emptied by the pulmonary 

 veins into the left auricle from which it 

 passes through the auriculoventricular 

 opening into the left ventricle; thence 

 into the aorta and its branches to the 

 systemic capillaries where it is dear- 

 terialized by an opposite exchange of 

 gases, i.e., yields up a portion of its 

 oxygen to, and absorbs carbon dioxid 

 from the tissues, and changes in color, 

 from scarlet-red to bluish-red. The 

 venous blood is again returned to the 

 systemic veins to the venae cavae. 



While there is but one circulation, 

 physiologists frequently divide the cir- 

 culatory apparatus into 

 i. The systemic circulation, which in- 

 cludes the movement of the blood from 

 the left side of the heart through the 

 aorta and its branches, through the 

 capillaries and veins, to the right side. 



FIG. 17. DIAGRAM OF CIRCULATION. 

 i. Heart. 2. Lungs. 3. Head and upper 

 extremities. 4. Spleen. 5. Intestine. 6. 

 Kidney. 7. Lower extremities. 8. Liver. 

 (Dalton.) 



