28 



Physiology of the Kidney 



By dividing the filtration rate (==inulin clearance) by 

 the renal plasma flow (=diodrast clearance) we can calcu- 

 late the fraction of the plasma which is filtered through the 

 glomeruli. This filtration fraction will depend upon systemic 

 blood pressure, the state of constriction or dilatation of the 

 glomerular arterioles, the permeability of the glomerular 

 capillaries, the intrarenal or capsular pressure, perhaps upon 

 the time of contact of the blood with the glomerular capil- 

 laries, and possibly upon other factors. By following the 

 filtration fraction under a variety of conditions we can learn 

 much about the activity of the glomerular apparatus. 



It will be convenient at this point to relate these quanti- 

 tative methods to the architecture of the kidney, as illus- 

 trated in Figure 5. It will be recalled that in each kidney 

 there are over a million nephrons, each of which is capable in 



FIGURE 5 



Figure 5. Functional types of nephrons to be exp<;ct€d 

 kidney. 



the normal and diseased 



