ELEMENTARY PHYSIOLOGY 



These vessels of the kidney are (i) the renal artery (Lat 

 renes, the kidneys), which conveys bright arterial blood direct 

 from the descending branch of the aorta ; (2) the renal vein, which 

 collects the blood that has circulated in the capillaries of the 

 kidney, and carries it direct to the ascending or inferior vena cava ; 



and (3) the ureter, which 

 carries away the fluid 

 secreted from the blood, 

 and conveys it to the 

 bladder. 



We must now study 

 a longitudinal section 

 of the kidney. A clean 

 cut should be made from 

 the outer convex surface 

 straight through to the 

 hilus. It will be noticed 

 that the ureter opens into 

 a cavity with a number of 

 short wide prolongations. 

 The cavity is called the 

 pelvis of the kidney, and 

 its branches, calices (Lat 

 cafyx, a cup). We also 

 observe that the solid por- 

 tion of the kidney consists 

 of an inner medullary 

 substance which has a 

 fibrous appearance, and 

 an outer cortical sub- 

 stance of a darker colour. 

 The medullary sub- 

 stance is not really fibrous, 

 but consists of a multitude 



R, right kidney ; U, ureter ; A, aorta ; Ar, right renal of minute tubes arranged 



v tei 3 ; ^ e> ve i n T a ""* inferior : Vr v righ l renal vein ; in separate conical masses 



Vu, bladder ; Ua. commencement of urethra. ,, *! . . , _., 



called the pyramids. The 



apex or point of each pyramid is turned toward the pelvis of the 

 kidney, into which it projects, presenting a number of minute 

 openings which are the terminations of the little tubes of the 

 pyramid. By squeezing the cut kidney, a little watery fluid may 

 be made to drain from these little tubes into the pelvis. 



From this cursory examination of the kidney it would appear 

 that the blood from the renal artery is abundantly supplied to the 

 cortical portion of the organ (hence the dark colour), where a 



L T a 



Fig. 157. The Kidneys, Bladder, and their 

 Vessels. Viewed from behind. 



