RENAL SECRETION. 



643 



so expand in the unyielding capsule of the kidney that the urinary 

 tubules are completely compressed, and nitration is, of course, at once 

 arrested. 



Various conditions may modify the blood pressure in the kidneys. 

 Thus, for example, the local blood pressure may be increased by general 



4. Spiral tube. 



13. Straight part of 

 collecting tube. 



9. Wavy part of as- 

 cending limb of 

 Henle's loop. 



Inner stratum of cor- 

 tex without Mal- 

 pighian corpuscles 



7 and 8. Ascending 

 limb of Henle's 

 loop tube. 



}] 



Sub-capsular layer 

 without Malpi- 

 ghian corpuscles. 



12. First part of col- 

 lecting tube. 



11. Distal convoluted 

 tubule. 

 A) A. Cortex. 



1U. Irregular tubule. 



3. Proximal convo- 

 luted tubule. 



9. Wavy part of as- 

 cending limb. 



2. Constriction or 

 neck. 



4. Spiral tubule. 



1. Malpighian tuft 

 surrounded by 



Bowman's capsul 



8- Spiral part of as- 

 cending limb of 

 Henle's loop. 



E. Boundary Zone. 

 5. Descending limb 

 of Henle's loop 

 tube. 



6. Henle's loop. 



C. Papillary Zone. 



Fig. 267.— Diagram of the Course of Two Uriniferous Tubules, 

 after Klein and Noble-Smith. (Landtiis.) 



increase of blood pressure or by a relaxation of the renal arteiy, accom- 

 panied by the constriction of other vascular areas, which, while dimin- 

 ishing the pressure in the renal artery itself, increases the pressure in its 

 capillaries. Of course, pressure* m&y be reduced in the kidney by the 

 reverse causes. 



