Kidneys and Urinary System - LO 3

3. Describe the basic vascular supply of the kidneys. 

Each kidney is supplied with blood from a renal artery which branches directly from the abdominal aorta, slightly inferior to the origin of the superior mesenteric artery. Renal arteries travel relatively posterior to the ipsilateral renal vein.  Renal veins drain directly into the IVC.  Because the aorta runs slightly to the left of midline, and the IVC is significantly right of midline, the arteries and veins have different lengths depending on if they are associated with the right or left kidney. Notably, the left renal v. is relatively long.

Each renal artery typically hosts five segmental arteries. Segmental arteries give rise to interlobar aa., which transition into arcuate aa. as the vessels move from the lateral surfaces of renal pyramids to the bases of renal pyramids. Both interlobar and arcuate aa. give rise to cortical radiate aa. (interlobular aa.), and cortical radiate aa. give rise to afferent arterioles, which feed glomeruli. Glomeruli are drained by efferent arterioles, which feed into peritubular capillaries and vasa recta.

The veins follow a similar pattern, with multiple tributaries coming out of the hilum of the kidney to coalesce to form the renal vein.

As the left renal v. is approximately 3x longer than the right renal v., a variety of veins draining structures on the left side of the body frequently drain into the left renal v. These include the:

• L. inferior phrenic v.

• L. suprarenal v.

• L. gonadal v.

The left renal v. occupies a narrow space, posterior to the superior mesenteric a. (SMA) and anterior to the abdominal aorta. An aneurysm in ether artery (typically in the wall of the aorta) may compress the left renal v., jeopardizing the return of blood from the left kidney, suprarenal gland, gonad, and inferior hemidiaphragm. This is known as left renal vein entrapment syndrome (aka nutcracker syndrome).