CHAPTER XXIII. 



THE BLADDER AND URETERS. 



BY HEINRICH OBERSTEINER, 



OP THE PHYSIOLOGICAL INSTITUTE OF THE UNIVERSITY OF VIENNA. 



THE BLADDER AND URETERS form a complex system of organs 

 that play a passive rather than an active part, their physiolo- 

 gical importance to all appearance being limited to receiving the 

 urine excreted by the kidneys, and facilitating its discharge 

 from the body. To this circumstance they owe the relative 

 simplicity of their anatomical characters, as well as the general 

 agreement they present in their structure. 



The bladder possesses at its upper part a peritoneal in- 

 vestment that covers it to a greater extent posteriorly than 

 anteriorly or laterally. The thickness of its walls alters with 

 its state of distention, varying in Man, apart from local 

 differences, between 2 and 15 millimeters. 



There is a general agreement in the structure of the urinary 

 bladder of most Mammals, and we shall therefore limit our 

 description to the characters it presents in Man. 



Amongst the Vertebrata the bladder is absent in Birds, and 

 in some Fishes, Amphibians, and Reptiles. The urine of these 

 animals is so rich in the salts of uric acid, that were it long 

 retained in the bladder, a deposit of too solid a nature would be 

 occasioned. The bladder of a few Reptiles and Amphibia (as the 

 Tortoise and Frog) opens like the ureters into the cloaca, so that 

 urine can be evacuated without having passed through the 

 bladder. A similar arrangement occurs in the Monotremata 

 amongst Mammals. 





