A COMPEND 



OF 



HUMAN PHYSIOLOGY. 



Introduction. An animal organism in the living condition exhibits a 

 series of phenomena which relate to growth, movement, mentality, and re- 

 production. During the period preceding birth, as well as during the period 

 included between birth and adult life, the individual grows in size and com- 

 plexity from the introduction and assimilation of material from without. 

 Throughout its life the animal exhibits a series of movements, in virtue of 

 which it not only changes the relation of one part of its body to another, but 

 also changes its position in space. If, in the execution of these movements, the 

 parts are directed to the overcoming of opposing forces, such as gravity, fric- 

 tion, cohesion, elasticity, etc., the animal may be said to be doing work. The 

 result of normal growth is the attainment of a physical development that will 

 enable the animal, and, more especially, man, to perform the work necessitated 

 by the nature of its environment and the character of its organization. In 

 man,, and probably in lower animals as well, mentality manifests itself as in- 

 tellect, feeling, and volition. At a definite period in the life of the animal it 

 reproduces itself, in consequence of which the species to which it belongs is 

 perpetuated. 



The study of the phenomena of growth, movement, mentality, and re- 

 production constitutes the science of ANIMAL PHYSIOIOGY. But as these 

 general activities are the resultant of and dependent on"the special activities 

 of the individual structures of which an animal body is composed, Physiology 

 in its more restricted and generally accepted sense is the science which in- 

 vestigates the actions or functions of the individual organs and tissues of the 

 body and the physical and chemic conditions which underlie and determine 

 them. 



