THE PROPERTIES OF MUSCULAR TISSUE 



101 



times they may be more contracted, sometimes less, but in health 

 seldom if ever completely relaxed. 



There are in the body a number of sphincters, circular bands 

 of smooth muscle which guard the openings of various organs 

 such as the stomach, large intestine, and bladder. These are 

 strongly contracted the greater part of the time, relaxation being 

 for them only an occasional occurrence. They maintain their 

 condition of strong contraction without fatigue and apparently 

 without much expenditure of energy, offering in this regard a 

 sharp contrast to skeletal muscle. 



