428 



2 HE HUMAN BODY. 



bladder can retain liquid under considerably higher pressure 

 when the spinal cord is intact than after destruction of its 



Ua 



Fio. 132. The renal organs, viewed from behind. R, right kidney; A, aorta; Ar, 

 right renal artery; Fc, inferior vena cava; Vr, right renal vein; 7, right ureter; 

 Fw, bladder; C7a, commencement of urethra. 



lumbar portion. The contraction of these urethra-con- 

 stricting muscles can be reinforced voluntarily. When some 

 amount of urine has accumulated in the bladder, it contracts 



