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HUMAN PHYSIOLOGY 



these breaks up again into a series of capillaries between 

 the convoluted tubules, and these pour their blood into the 

 interlobular veins (IL.V.). This arrangement must help 

 to maintain a high pressure in the capillary loops of the 

 glomerular tuft. 



Physiology of Secretion. 



I. Secretion in the Malpighian Bodies. A consideration 

 of the structure of the Malpighian bodies tends to the conclu- 



FlO. 156. Diagram of the Structure of the Kidney. M.P., Malpighian 

 Pyramid of the Medulla; M.R., Medullary Ray extending into 

 Cortex; L., Labyrinth of Cortex; M.B., a Malpighian Body con- 

 sisting of the Glomerular Tuft and Bowman's Capsule ; P.C.T., a. 

 Proximal Convoluted Tubule; H.L., Henle's Loop on the Tubule; 

 D.C.T,, Distal Convoluted Tubule ; C.T., Collecting Tubule ; R.A., 

 Branch of Renal Artery, giving off IL.A.. Interlobular Artery, to 

 supply the Glomeruli and the Convoluted Tubules ; IL. V, , Inter- 

 lobular Artery bringing Blood back from the Cortex. 



sion that in them the water of the blood must filter out into 

 Bowman's capsule, under the influence of the intravascular 

 pressure. That they do act in this way is demonstrated by 

 (a) the influence of the blood pressure in the kidneys on the 

 flow of urine, and (6) the effect of increasing the pressure in 

 the ureters on the flow of urine. 



