158 THE ABDOMEN. 



main channels, the lungs, skin, and kidneys, and the 

 materials are of four kinds, urea, carbon dioxide, salts, 

 and water. The lungs carry off carbon dioxide and 

 water chiefly, the skin these and inorganic salts, while 

 the kidneys eliminate practically all the urea as well 

 as inorganic salts and water. When the kidneys are 

 not working the skin carries off much urea. In fact, 

 a close relationship exists between the kidneys and the 

 skin in the matter of excretion. Thus, with increased 

 perspiration in warm weather comes decreased urine, 

 while in cold weather the blood is sent in and the 

 urine increased in amount. 



To incite action of the kidneys drugs known as 

 diuretics may be used. These act in two ways, by stim- 

 ulating the kidney cells directly and by acting on the 

 general circulation or nervous system. Any emo- 

 tional or nervous excitement increases the flow of 

 urine. 



There are certain abnormal constituents of urine, 

 of which the two most important are albumen and 

 sugar. The former is found only when there is some 

 disturbance of the kidneys, ureters, or bladder, and its 

 presence usually denotes some change in the cells lining 

 the urinary tract. It may occur in congestion of the 

 kidney as well as in disease. Sugar is found only in dia- 

 betes, the amount varying with the severity of the dis- 

 ease. In jaundice certain bile pigments are present in 

 the urine, giving it a dark brown color and to the foam 

 a greenish-yellow color. Even normal urine has some 

 sediment upon standing, consisting of cells from the 

 urinary tract and mucus. In very acid urine after 

 standing a heavy sediment, whitish or pinkish, i.e., brick 

 dust, in color, is thrown down. It does not necessar- 

 ily denote disease, but shows the urine is acid and con- 

 centrated. In alkaline urine there is a sediment due 

 to phosphates. 



Rupture of the kidney occurs but is not so serious as 

 rupture of the liver or spleen because the kidney is sit- 



