PHYSIOLOGY AND HYGIENE 



INTRODUCTORY CHAPTER 



CELL STRUCTURE 



Divisions Cells Structure of the Cell Cell Reproduction Cell 

 Nourishment Cell Motion 



1. Divisions. The study of the human body includes : 



1. Anatomy, which is the study of the structure of the 

 human body. This is again subdivided into, first, gross 

 anatomy, which is the study of the structure of the body as 

 made by careful dissection ; and, second, microscopic anatomy, 

 also called histology, which is the minute study of the various 

 tissues and organs composing the body, by the aid of the 

 microscope. 



2. Physiology, which is the study of the functions of the 

 various organs and tissues of the body. 



3. Hygiene, which is the study of the best means of pre- 

 serving the body's health. 



2. Cells. If we examine a portion of any one of the struc- 

 tures of the human body under the microscope, we find that it 

 is composed of countless small bodies, which are called cells. 

 These cells have distinctive shape, size, and form, in each of 

 the different structures. Each one of the cells aids in the 

 function which characterizes its tissue ; thus, for instance, the 

 many muscle cells composing one of the muscles of the arm 

 contract, and their united contraction causes the entire muscle 

 to contract. And, again, of the many cells composing the liver, 

 each aids in secreting its small portion of bile, and in perform- 

 ing its other functions. 



1. What is anatomy ? Physiology? Hygiene? 2. What are cells ? 

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