176 THE SKIN AND KIDNEYS 



reservoir for the urine until it is expelled from the body. When 

 the bladder is moderately distended, it holds about one pint. The 

 average quantity of urine secreted in twenty-four hours by the 

 average adult is about forty ounces, or 1.2 liters. The kidneys 

 eliminate toxic materials formed in the body during illness. In 

 ridding the body of its poisons, the kidneys are frequently dam- 

 aged. In order to keep them in as good condition as possible, 

 about seven glasses of water should be drunk daily. This will 

 dilute any toxic materials present and keep the kidneys well 

 washed. Too much animal protein food should not be eaten as 

 the kidneys may become overworked, in eliminating the urea, an 

 oxidation product of proteins. 



QUESTIONS AND SUGGESTIONS 



1. What is excretion? 



2. Name the organs of excretion and discuss how each one elimi- 

 nates waste. 



3. Name four functions of the skin and explain the ways in which 

 the skin is adapted to perform each function. 



4. Discuss the hygiene of the skin. 



5. What unhygienic habits may injure the skin ? 



6. What is the relation of the work of the skin to the work of the 

 kidneys ? 



7. Discuss the value of water to the skin and kidneys. 



SUPPLEMENTARY READING 



Kimber, D. C., and Gray, C. E., Textbook of Anatomy and Physiology (The 

 Macmillan Co.). 



