THE NERVOUS SYSTEM 



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domen. The largest of these sympathetic ganglia is the solar 

 plexus, located just below the diaphragm, another is near the heart, 

 and a third low down in the abdomen. 



The operation of the sympathetic system is not well understood 

 but it certainly controls the secretion of glands, the regulation of 

 blood supply in arteries, heart action, and probably many other 

 internal activities of which we are not conscious, but without which 

 we could not live. 



The " sympathetic system " has nothing to do with " sympathy " 



BRAIN - (MID-SECTION) 



FIG. 133. Diagram of mid-section of human brain showing position of 

 important parts. 



in its usual sense, but is so named since it seems to keep the in- 

 voluntary internal organs working in harmony, much as the cerebel- 

 lum coordinates the action of the voluntary organs. 



It appears that our nervous system is capable of controlling 

 several kinds of action, for example: 



1. Voluntary actions, originating in the cerebrum and co- 

 ordinated by cerebellum. 



