Human Kidney Structure and Function Pathway

Kidney location and gross anatomical features

In humans, the kidneys are two reddish-brown, bean-shaped organs located in the retroperitoneal space behind the abdomen, one on each side of the spine. Their vertebral level is approximately T12 to L3, and they lie at a slightly oblique angle. Because of the liver’s position, the right kidney is typically slightly lower and smaller than the left. Each kidney is associated with an adrenal gland superiorly and is attached to a ureter that carries urine to the bladder. The kidneys are enclosed by a renal capsule and surrounded by fat and fascial layers (perirenal fat, renal fascia, and pararenal fat), with the renal hilum on the concave border where the renal artery enters and the renal vein and ureter leave. Grossly, the kidney’s functional tissue (parenchyma) is divided into an outer renal cortex and an inner renal medulla. The medulla is organized into multiple cone-shaped renal pyramids (grossly described as about 8–18 lobes), separated by renal columns of cortex. Each pyramid drains urine via a renal papilla into a minor calyx; minor calyces join to form major calyces, which drain into the renal pelvis and then into the ureter. The renal sinus (a fat-filled cavity) houses the renal pelvis and calyces and separates these collecting structures from the medullary tissue. The kidney’s gross anatomical features also include the renal hilum and surrounding hilar fat and lymphatic tissue.

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Renal capsule, fascia, and perirenal fat

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