1 88 ANATOMY AND PHYSIOLOGY FOR NURSES 



lation stimulates the muscular walls to contract, the resist- 

 ance of the sphincter at the neck of the bladder is over- 

 come, and the urine is ejected through the urethra. 



Involuntary micturition may occur as a result of spinal 

 injury, involving the nerve-centers that send nerves to the 

 bladder. It may also be due to a want of tone in the mus- 

 cular walls, or it may result from abnormal irritation. 



The Urine. General Character of the Urine. 

 Normal urine may be described as a transparent, watery 

 fluid, of a pale yellow color, acid reaction, a specific gravity 

 of 1018 to 1020, and possessing an odor that can only be 

 described as characteristic or urinous. Bach one of these 

 characters is subject to some variation within the limits 

 of health as well as in disease. 



The transparency of urine may be diminished in health 

 by the presence of mucus derived from the genito-urinary 

 tract, or by the deposits of salts. In disease the urine 

 may become clouded by the presence of pus. 



The color of urine depends mainly upon the amount 

 of water it contains ; also upon a diminution or increase of 

 the coloring matter. In hysteria, in which the urine is 

 copious in amount, the color is very light, while in fevers, 

 in which it is scanty, the color is very high. It may take 

 on abnormal color as the result of the ingestion of certain 

 foods or medicine, or this may be due to a diseased condi- 

 tion. 



The reaction of urine should always be tested from a 

 collection of urine passed during twenty-four hours, for it 

 is affected by diet and exercise; the reaction of mixed urine 

 is normally acid. 



The specific gravity of urine depends upon the amount 

 of solid waste matter present in the urine. In health it 

 may vary from 1015 to 1025. When the solids are dis- 

 solved in a large amount of water, the specific gravity will 

 naturally be lower than when, from a deficiency of water, 



