336 EESPIEATION 



Inflammatory diseases. — Sudden changes of temperature 

 affect the vaso-motor nerves, and thus the blood supply to 

 certaua parts of the body. When the skin is suddenly 

 chilled in any way the blood vessels of the mucous mem- 

 brane, which lines the air passages, become charged with 

 blood. If under such conditions these membranes become 

 infected with bacteria, inflammation results. When this 

 inflammation is limited to the nasal cavity we call the result 

 a cold in the head. When the pharynx membrane is 

 inflamed a sore throat is the result. A chest cold is due to 

 inflammation of the windpipe and bronchial linings. If 

 this inflammation spreads to the linings of the bronchial 

 tubes, we call it bronchitis, while infection of the air sacs 

 themselves produces pneumonia. The reactions involved in 

 these various types of inflammatory diseases of the mucous 

 membrane have already been discussed in the paragraphs 

 on inflammation. (See p. 206). All forms are accom- 

 panied by great secretion of mucus, which tends to clog 

 the air passages and render Ijreathing difficult. 



In certain cases the pleura which lines the thoracic cavity 

 becomes inflamed, the two surfaces rub together, produc- 

 ing severe pains, while the secretion of pleural Uquid 

 increases to an abnormal amount and produces pressure 

 upon the lungs. Such a disease is called pleurisy, and can 

 often be relieved only by tapping the pleural cavity and 

 extracting the excess of fluid collected there. 



The treatment for inflammatory diseases depends upon 

 the reducing of inflammation and the restoration of the 

 blood supply and secretion to their natural amount. In 

 severe cases .a physician should always be consulted. 



Other germ diseases.— Inhaled air often contains disease 

 germs of various kinds. If these germs lodge in the mem- 



