QUESTIONS 387 



several different structures by reflex actions taking 

 place between these groups of ganglia and their asso- 

 ciated neurones. The sympathetic nerves convey 

 nerve impulses which, in response to stimuli trans- 

 mitted to them through ganglia and their connections 

 with the cerebrospinal system, control the secretion 

 of the glands; others control the caliber of the blood- 

 vessels by vasoconstrictor and vasodilator nerves, 

 passing to the muscular coat -of the vessel, the former 

 regulating the contraction, the latter the dilatation 

 of the bloodvessels; others regulate the force and 

 rate of the heart muscle called cardio-accelerator, 

 which increase the action, and cardio-inhibitor, which 

 decrease it. Other nerves convey impulses to the 

 organs of special sense, as those regulating the size 

 of the pupil. Emotional states, either of an exciting 

 or depressing nature, influence the activity of the 

 sympathetic system by impulses transmitted through 

 the spinal cord and ganglia from the brain, which 

 reach the organs of digestion, etc., by reflex pathways 

 established between the ganglia and ganglionic plexuses 

 and their secreting cells and bloodvessels. 



QUESTIONS 



1. Give the divisions of the nerve system. 



2. What parts of the nerve system are included under the 

 cerebrospinal system? 



3. What is the essential cell structure of all nerve energy and 

 reflex called? 



4. Name the protoplasmic processes given off from a neurone. 



5. How large are the bodies of nerve cells? 



6. Give the classification of neurones as regards their number 

 of processes. 



7. Describe a dendrite of a neurone. Do they increase the 

 functionating surface of a neurone? 



8. What is the function of the dendrites as regards nerve impulses? 



9. Describe an axone or axis-cylinder. 



10. How long is an axone? 



11. How many axones are given off from a neurone? Name 

 them as to the numbers. 



12. What do you understand by tolendria? 



