CHAPTER VII 



COORDINATION AND CONTROL 

 (1) THE NERVOUS SYSTEM 



Thus far we have been concerned chiefly with the parts of the body that 

 account for most of its bulk and form and that carry on the greater part 

 of its metabolic activities. We have seen that one of these functional units, 

 the circulatory system, provides an important measure of coordination 

 by serving all parts of the body with rapid and continuous transportation 

 of supplies and products. In this and in the following chapter we now 

 turn to a consideration of two more specialized coordinating agencies — 

 the nervous system and the endocrine glands. These unite the body into 

 a single working entity, the individual; they control the pattern of its 

 development and regulate the functioning of its parts; and they enable the 

 individual to make the adjustments required by changes in its internal 

 state and external environment. 



The two coordinating systems are to a degree independent of one 

 another, and each has its own particular functions and responsibilities. 

 The nervous system is especially concerned with immediate adjustments to 

 external and internal conditions, with causing appropriate responses to 

 specific stimulations, and with the regulation of various precise vital 

 activities. It is also the seat of sensation, consciousness, memory, and 

 intelligence. The other system is made up of the interconnected and 

 interacting endocrine glands. It is more particularly concerned with 

 general body states and adjustments to internal changes and especially 

 with the maintenance of balance between various phases of metabolic 

 processes. In spite of these differences and the very unlike structure and 

 mode of functioning of the two systems, they are closely integrated, and 

 most of the activities of the body are, in consequence, subjected to a 

 dual nervous and endocrine control. 



It is common knowledge that the brain and spinal cord, encased in and 

 protected by the skull and backbone, exercise a high degree of control 

 over the various parts of the body. Together with the nerves, they con- 

 stitute the nervous system, which is probably the most complex part 

 of the entire body. Although much of the more intricate and finer detail 

 of the functioning of this system is beyond our present knowledge, the 



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