THE CIRCULATION OF THE BLOOD 



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203. The Aorta and its Great Branches. Branches of the 

 aorta carry blood from the heart to the tissues. They are called 

 arteries. After leaving the heart the aorta rises towards the 

 neck, but soon curves downwards to form the arch of the 

 aorta. This great 

 tube passes between 

 the lungs to the back, 

 then runs down along 

 the spine through 

 the diaphragm. 



In the abdomen it 

 divides into two 

 branches, one of 

 which goes to each 

 lower limb. 



Branches spring- 

 ing from the arch of 

 the aorta supply the 

 head and the arms. 



While the aorta 

 is passing down the 

 spine it gives off 

 branches to nourish 

 the lungs and the 



Showing the carotid artery and jugular vein on the 

 right side, with some of their main branches ; also 

 some large nerve trunks. 



FlG - 



important organs of 

 the abdomen. 



Experiment 41. To illustrate how the heart pumps blood. Sink 

 the suction end of a bulb syringe into water. Press the bulb. As 

 the bulb expands, it fills with water; as we press it again, a valve 

 prevents the water from flowing back, and it is driven out in a jet 

 along the main pipe. The suction pipe represents the veins ; the 

 bulb, the heart; and the tube end, the arteries. 



