CHAPTER XIV 

 THE URINARY SYSTEM 



This system includes the kidneys, which are two large bean-shaped 

 glands, together with their excretory passages, the ureters, which conduct 

 the urine to the urinary bladder, whence it is voided through the urethra. 



THE KIDNEY 



Each kidney is a gland of the compound tubular_tye. measuring 

 about four and one-half inches irTTength, two and one-half inches in 

 width, and one and one-half inches in thickness. Its secretion, the urine, 

 is produced by the uriniferous or renal tubules, which are long tortuous 

 canals beginning near the surface of the kidney and finally ending at 

 the hilum of the organ where they pour their secretion into the calyces 

 of the renal pelvis. The uriniferous tubules are in intimate relation 

 with the renal blood-vessels which supply rich capillary plexuses to the 

 entire extent of the tubules. Each uriniferous tubule consists of both 

 tortuous and straight portions, and these are so regularly disposed as to 

 produce macroscopical variations in the appearance of the different por- 

 tions of the renal parenchyma according as the tortuous or the straight 

 portions of the tubules predominate. These variations result in the fol- 

 lowing topographical subdivisions. 



TOPOGRAPHY OF THE KIDNEY 



If the kidney be divided parallel to its long axis by an incision extend- 

 ing from its convex surface to the hilum, the cut surface shows that the 

 parenchyma is divisible into a superficial cortex and a central medulla. 

 The slit-like Jiilum of the organ opens into a deep excavation, the rp.n(\], 

 sinus^ which is occupied by the renal pelvis and its subdivisions, the 

 infundibula and calyces, ^i^w^^i_^^ m Achilla pj^ts in the form 

 of several conical pyramids. The pelvis of the kidney, the expanded 



423 



