EXCRETION OF MATTER FKOM THE BODY 



423 



SECEETION OF URINE 

 Structure of the Kidney 



(This must be studied practically.) The kidney (fig. 168) is 

 a compound tubular gland, consisting of innumerable tubules, 

 each made up of 



(1) A closed extremity or Malpighian body (M.B.\ consisting 

 of an expansion at the end of the tubule Bowman's capsule 

 into which a tuft of capillary vessels the glomerulus projects. 



FIG. 168. 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. t a Malpighian body consisting of the glomerular tuft and 

 Bowman's capsule ; P.C.T., a proximal convoluted tubule ; H.L., Henlo's 

 loop on the tubule; D.C.I'., distal convoluted tubule; C.T., collecting 

 tubule ; E.A., branch of renal artery, giving off IL.A., interlobular artery, 

 to supply the glomeruli and the convoluted tubules ; IL. V., interlobular 

 artery bringing blood back from the cortex. 



(2) Extending away from this is a proximal convoluted tubule 

 (P.C.T.) lined by pyramidal and granular epithelial cells. This 

 dives into the medulla, becomes constricted and lined by a 

 transparent flattened epithelium, and is known as the descending 

 limb of the looped tubule of Henle. Turning suddenly upwards 



