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TEXT-BOOK OF PHYSIOLOGY. 



muscle the contraction and relaxation periods are of equal duration. 

 With the amphibian muscle they are of unequal duration, as a rule. 

 In both classes of animals the character of the record, a succession 

 of large and small contractions, would indicate that the general 

 rhythmic movement is compounded of two or three secondary 

 rhythms which differ in rate and character. A single pulsation may 

 be recorded by stimulating the bladder muscle with the induced or the 

 make and break of the constant current. A curve of such a contrac- 

 tion is shown in Fig. 41. The contraction takes place more rapidly 

 than the relaxation; the two phases occupying five and thirty- five 

 seconds respectively. The latent period covered 0.25 second. With 

 other muscles the time relations are slightly different. Tetanization 

 of the bladder muscle of the cat occurred when 

 the stimuli succeeded each other with a certain 

 rapidity; the interval between stimuli approxi- 

 mating a period somewhat less than two sec- 

 onds. This muscle responds to variations in 

 temperature, to strength of stimulus, to the 

 load, in a manner similar to, if not identical 

 tvkk, the^skele^al muscle . 

 ' ^Th6 4 oFu^pfipii of the Visceral Muscle. 

 In. a c general way it may be said that the vis- 

 ce^^i^niupcl^^eteh^Anes and regulates the pas- 

 sage through cho fiscus or organ of the material 

 contained within it. The food in the stomach 

 and~lntestines is subjected to a churning pro- 

 cess by the muscles, in consequence of which 

 the digestive fluids are more thoroughly incor- 

 porated and their characteristic action in- 

 creased. At the same time the food is carried 

 through the canal, the absorption of the nutri- 

 tive material promoted, and the indigestible 

 residue removed from the body. The blood 

 is delivered in larger or smaller volumes ac- 

 cording to the needs of the tissues through a relaxation or contrac- 

 tion of the muscle-fibers of the blood-vessels. The urine is forced 

 through the ureter and from the bladder by the contraction of their 

 respective muscles. The mode of action of the individual muscles 

 will be described in successive chapters. 



Ciliary Movement. The free surface of the epithelium cover- 

 ing the mucous membrane in certain regions of the body is charac- 

 terized by the presence of delicate filamentous processes termed 

 cjlia. (See Fig. 42.))^ Ciliated epithelium is found in man and 

 mammals generally, in the nose, Eustachian tnhp ; . larynx? W1 'th the 

 exception of the vocal membranes, trachea and bronchial tubes\Vas 



FIG 



41. THE CURVE 

 OF CONTRACTION 

 OF THE BLADDER 

 MUSCLE AT BODY- 

 TEMPERATURE IN 

 RESPONSE TO A 

 SINGLE INDUCTION 

 CURRENT. THE 

 TIME IS INDICATED 

 IN SECONDS. 

 (Stewart) 



