260 



UNCONSCIOUS NERVOUS OPERATIONS 



378. The Kidneys (Fig. 118) are bean-shaped organs, 

 lying on each side of the lumbar portion of the backbone. 



They are dark red in color, 

 about four inches long, two 

 and a half broad, and about 

 one inch in thickness. At 

 the center of the concave, 

 or inner edge, of each kid- 

 ney the arteries enter and 

 the veins leave the organ. 

 The arteries are branches of 

 the aorta ; the veins empty 

 into the inferior vena cava. 

 From the same portion of 

 each kidney passes another 

 tube, the ureter, which con- 

 veys the urine secreted by 

 the kidneys to the sac called 

 the bladder, in the lower 

 part of the abdomen, for 

 storage. The ureters pass 

 obliquely through the wall 

 of the bladder, so that return 

 of the contents of the latter 

 is prevented. 



379. Structure of the Kidneys. By dividing a kidney 

 lengthwise through the middle, two distinct parts may be 

 seen : an outer, granular portion, called the cortex, lying 

 next to the inclosing capsule, and an inner medullary por- 

 tion (Figs. 118 and 120). The latter consists of a number 

 of conical parts, called pyramids, with their bases toward 

 the cortex. In the cortical portion the tiny uriniferou* 

 tubules commence around tufts of blood capillaries {glo- 



Fig 11 9. -The kidneys and bladder 

 viewed from behind. 



A aorta, from which the renal arter- 

 ies extend to the kidneys. 



V inferior vena cava, from which the 

 renal veins extend to the kidneys. 



u ureters. 



