24 



LABORATORY STUDIES IN ZOOLOGY 



The Arteries. — While the numerous blood vessels of the body 

 may be confusinji; at first, there is no need for viewing their study 

 as an impossible or even a difficult task. There are certain 

 observations which, if kept in mind, will facilitate this study: 



1. The heart is the central organ of the whole blood system. 



2. Arteries convey currents away from the heart. 



3. Veins convey currents toward the heart. 



4. The organs of every region of the body must be supplied 

 with blood from the heart. 



5. The organs of every region must be drained of blood toward 

 the heart. 



Fig. 1. 



Based upon the distribution of arteries to the various organs 

 the body may be divided into three main regions: (1) the head, 

 (2) the lungs and skin, (3) the trunk, arms, and legs. Each 

 of these regions is supplied on each side by its own main trunk 

 leaving the heart. Figure 1 is a schematic representation of the 

 three regions and the arteries which supply them and as well the 

 main vessels of the whole body. It should be kept in mind that 

 this figure is schematic and not intended to show actual details. 

 By a careful study of this schema aptitude will be acquired for 

 the dissection and study of the vessels themselves. 



