THE HUMAN BODY 



CHAPTER I 



THE GENERAL STRUCTURE AND COMPOSITION OF THE 



HUMAN BODY 



Definitions. The living Human Body may be considered from 

 either of two aspects. Its structure may be especially examined, 

 and the forms, connections and mode of growth of its parts be 

 studied, as also the resemblances or differences in such respects 

 which appear when it is compared with other animal bodies. Or 

 the living Body may be more especially studied as an organism 

 presenting definite properties and performing certain actions; and 

 then its parts will be investigated with a view to discovering what 

 duty, if any, each fulfils. The former group of studies constitutes 

 the science of Anatomy, and in so far as it deals with the Human 

 Body alone, of Human Anatomy; while the latter, the science con- 

 cerned with the uses or in technical language the functions of 

 each part is known as Physiology. Closely connected with physi- 

 ology is the science of Hygiene, which is concerned with the con- 

 ditions which are favorable to the healthy action of the various 

 parts of the Body; while the activities and structure of the diseased 

 body form the subject-matter of the science of Pathology. 



Tissues and Organs. Histology. Examined merely from the 

 outside our Bodies present a considerable complexity of structure. 

 We easily recognize distinct parts as head, neck, trunk and limbs; 

 and in these again smaller constituent parts, as eyes, nose, ears, 

 mouth; arm, forearm, hand; thigh, leg and foot. We can, with 

 such an external examination, go even farther and recognize dif- 

 ferent materials as entering into the formation of the larger parts. 

 Skin, hair, nails and teeth are obviously different substances; 

 simple examination by pressure proves that internally there are 

 harder and softer solid parts ; while the blood that flows from a cut 

 finger shows that liquid constituents also exist in the Body. The 



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