70 HUMAN PHYSIOLOGY. 



KIDNEYS. 



The Kidneys are the organs for the secretion of urine ; they resemble 

 a bean in shape, are from four to five inches in length, two in breadth, and 

 weigh from four to six ounces. 



FIG. 8. 



1" . 



Longitudinal section through the kidney, the pelvis of the kidney, and a number of renal 

 calyces. A, branch of the renal artery; U, ureter; C, renal calyx ; i, cortex ; i', 

 medullary rays; i", labyrinth, or cortex proper; 2, medulla; 2', papillary portion of 

 medulla, or medulla proper; 2", border layer of the medirila; 3, 3, transverse section 

 through the axes of the tubules of the border layer ; 4, fat of the renal sinus ; 5, 5, 

 arterial branches ; *, transversely coursing medulla rays. 7ysen, after Henle. 



They are situated in the lumbar region, one on each side of the vertebral 

 column, behind the peritoneum, and extend from the nth rib to the crest 



