Efferent Circulation
Blood is carried out of the glomerulus by an efferent arteriole instead of a venule, as is observed in most other capillary systems. This provides tighter control over the bloodflow through the glomerulus, since arterioles can be dilated and constricted more readily than venules, owing to arterioles' larger smooth muscle layer (tunica media).
Efferent arterioles of juxtamedullary nephrons (i.e., the 15% of nephrons closest to the medulla) send straight capillary branches that deliver isotonic blood to the renal medulla. Along with the loop of Henle, these vasa recta play a crucial role in the establishment of the nephron's countercurrent exchange system.
The efferent arteriole, into which the glomerulus delivers blood, empties into an interlobular vein.
Read more about this topic: Glomerulus
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