Kidney Blood Supply
The kidneys receive blood from the renal arteries, which branch perpendicularly from the descending (abdominal) aorta. These arteries provide the kidney with an ample blood supply, amounting to approximately 20% – 25% of the heart’s output, equating to about 1 liter of blood per minute.
Before entering the renal hilum, the renal artery divides into segmental arteries.
The segmental arteries divide into interlobar arteries, which pass through the renal columns to provide blood to the renal lobes.
Blood is directed towards the renal lobes because they contain the nephron tubules that form urine. A kidney usually has 7 to 9 renal lobes, each consisting of two regions. The lighter outer region is part of the renal cortex, and the darker inner region, the renal pyramidal, is part of the renal medulla.
The arcuate arteries branch from the interlobar arteries and enter the renal lobes, where they run alongside the arched intersections between the renal cortex and renal medulla.
Cortical Radiate Arteries
Cortical radiate arteries (interlobular arteries) branch at right angles and extend into the renal cortex from the arcuate arteries.
Arterioles and Glomerulus
The cortical radiate arteries give off afferent arterioles that deliver blood to the Bowman’s capsules of nephrons.
Within a Bowman’s capsule, an afferent arteriole forms a tuft of high-pressure capillaries called the glomerulus. The glomerulus and the Bowman’s capsule together form the renal corpuscle. Blood is filtered across the capillary walls of this tuft through the glomerular filtration barrier, which yields its filtrate of water and soluble substances to the interior space of the Bowman’s capsule.
The glomerular capillaries eventually merge to form an efferent arteriole, which exits the Bowman’s capsule.
Capillaries Near the Nephron Tubules
The efferent arterioles branch extensively, forming a network of capillaries that wind around the renal tubules of the nephrons. The proximity of the capillaries and renal tubules allows the exchange of substances between the neighboring structures.
The capillaries that travel alongside the proximal and distal convoluted tubules of the nephrons are called the peritubular capillaries.
Vasa recta Capillaries
Those that travel alongside the loops of Henle of the juxtamedullary nephrons are called the vasa recta capillaries.
Cortical Radiate Veins
After the blood is cleansed and rebalanced by the nephrons and nearby capillaries, it drains into the cortical radiate veins (interlobular veins).
The cortical radiate veins merge at right angles with the arcuate veins, which carry the blood away from the renal lobes.
The blood from the arcuate veins moves to the interlobar veins and flows through the renal columns along the edges of the renal lobes.
Blood is then carried away from the kidney by the renal vein and delivered to the inferior vena cava to transport it to the heart.
Kidney Blood Flow Activity
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Kidney Blood Flow Chart
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References and Attributions
Cleveland Clinic – “Renal Artery.”
ScienceDirect – “Kidney Blood Flow.”
ScienceDirect – “Kidney Circulation.”
OpenStax; Anatomy and Physiology – “Gross Anatomy of the Kidney” (Access for free at – https://openstax.org/books/anatomy-and-physiology/pages/1-introduction).
Radiopaedia – “Kidneys.”
University of Nottingham – “Anatomy of the KIdneys: Blood Flow“.