Figure 20-1 Anatomic relationships of the nephron and the renal vasculature. The left side of the diagram represents the renal vasculature as distributed through the inner medulla, outer medulla, and cortex. Arteries are drawn as solid lines, veins as hollow tubes. The renal artery divides serially into interlobar arteries (1), arcuate arteries (2), and interlobular arteries (3). The afferent arterioles (5) branch off laterally and provide the capillary tufts of the renal glomeruli in the outer cortex (7a), whose efferent arterioles (6) supply the cortical capillary network (not shown). In the juxtamedullary zone (7b), the efferent arterioles become the vasa recta, which are closely applied to the long loops of Henle (8, 8a, 9). The venous drainage consists of stellate veins (4), interlobular veins (3a), arcuate veins (2a), and interlobar veins (1a). The right side of the diagram represents two nephrons. On the left is the more numerous superficial cortical nephron with a short loop of Henle. On the right is the juxtamedullary nephron with a long loop of Henle, which dives deep into the inner medulla to generate the hyperosmotic interstitium required for tubular urine concentration. ATL, ascending thin loop of Henle; CCD, cortical collecting duct; DT, distal tubule; DTL, descending thin loop of Henle; G, glomerulus; IMCD, inner medullary collecting duct; OMCD, outer medullary collecting duct; PT, proximal tubule; TAL, thick ascending loop. (Used with permission from Kriz W: A standard nomenclature for structures of the kidney. Kidney Int 33:1–7, 1988.)