THE HUMAN ORGANISM 295 



8. The muscular system 



Striped muscles 



Distribution over body 



Attachment to skeleton (ligaments) 



Control by cerebrospinal (voluntary) nerves 



Control (indirectly) by sympathetic nerves 

 Unstriped muscles : in blood vessels ; in digestive tract 

 Relation of muscular activity to 



Breathing 



Heart action . 



Excretion 



Digestive processes and elimination 



9. Exercise and rest 



Importance of exercise 



For the muscles 



For the viscera 



For general health 

 Desirable kinds of exercise 



Use whole body 



Arouse interest 



Increase heart action 



Increase breathing 



Increase perspiration 

 Importance of rest and sleep 



QUESTIONS 



1. What is there to show that most people have some concern with 

 health ? 



2. What methods are there for learning about the structure of the 

 human body ? 



3. What are vertebrates ? How do they differ from other animals ? 



4. What are the classes of vertebrates ? How do they differ from one 

 another ? 



5. In what ways does the general structure of a frog resemble that 

 of the human body ? In what ways do the two differ ? 



6. How do the structure and ihe appearance of the frog fit into his 

 way of life ? 



7. How does a frog get his food ? Of what does the food consist ? 

 What are some special adaptations of the frog to food-getting ? 



