PHYSIOLOGY. 



GENERAL CONSIDERATIONS AND PROXIMATE 

 PRINCIPLES. 



Define human physiology. 



HUMAN PHYSIOLOGY is that branch of biology which refers to 

 the functions and properties of the organs in the living human 

 body. 



In entering upon the study of the functions of organs it becomes 

 desirable to understand something of the nature of the fundamental 

 elements of living tissue which we call cells. 



What are cells? 



Cells may be described as nucleated masses of protoplasm of 

 microscopic size, usually possessing limiting membranes known 

 as cell-walls, and capable of passing through the changes which 

 are characteristic of life and death. Some cells do not possess 

 a nucleus, but this is quite exceptional. More commonly each 

 cell has a nucleus or more than one, and in many instances there 

 is a nucleolus within the body of the nucleus. 



What is protoplasm ? 



Protoplasm is an unstable albuminoid substance of more or less 

 gelatinous nature. Its reactions are those of albumin (coagulation 

 by heat and mineral acids), and its chemical composition is of vary- 

 ing proportions of the elements C, H, N, 0, S. Protoplasm is living 

 albumin or proteid. 



Illustrate the life of the cells by the amoeba. 



The characteristic changes through which cells pass are well 

 illustrated by the amoeba : (a) The power of spontaneous move- 

 ment, in which a small portion of the cell is first advanced, and 

 2 Phy. 17 



