PATHOLOGY 



PATHOLOGY is the science which treats of disease, its 

 causes, symptoms, and results. 



Disease is a condition of a living organism character- 

 ized by abnormality in structure, in function, or in both 

 combined. 



CHAPTER XVI 

 ETIOLOGY OF DISEASE 



THE causes of disease are numerous. As we have 

 already learned, bacteria and their toxins are the cause 

 of diseases, and in our daily combat with these minute 

 agencies we are prone to lose sight of the other innumer- 

 able causes of abnormality of structure and function 

 which exist throughout nature. 



Traumatism is the name given to mechanical injury. 

 Besides the ordinary wounds, bruises, contusions of the 

 soft tissues, and fractures of bones, gradual pressure 

 may cause atrophy, and if prolonged or of increased 

 intensity may result in necrosis or gangrene. 



Heat. Local excess of heat produces various lesions, 

 depending upon its intensity and length of application, 

 from simple hyperemia, vesicle formation, to charring 



126 



