<P> Located at the rear of the abdominal cavity in the retroperitoneal space, the kidneys receive blood from the paired renal arteries, and drain into the paired renal veins . </P> <P> Renal physiology is the study of kidney function, while nephrology is the medical speciality concerned with kidney diseases . Diseases of the kidney are diverse, but individuals with kidney disease frequently display characteristic clinical features . Common clinical conditions involving the kidney include the nephritic and nephrotic syndromes, renal cysts, acute kidney injury, chronic kidney disease, urinary tract infection, kidney stones, and urinary tract obstruction . Various cancers of the kidney exist . The most common adult renal cancer is renal cell carcinoma . Cancers, cysts, and some other renal conditions can be managed with removal of the kidney . This is known as nephrectomy . When renal function, measured by the glomerular filtration rate, is persistently poor, dialysis and kidney transplantation may be treatment options . Although they are not normally harmful, kidney stones can be extremely painful . </P> <P> In humans, the kidneys are located high in the abdominal cavity, one on each side of the spine, and lie in a retroperitoneal position at a slightly oblique angle . The asymmetry within the abdominal cavity, caused by the position of the liver, typically results in the right kidney being slightly lower and smaller than the left, and being placed slightly more to the middle than the left kidney . The left kidney is approximately at the vertebral level T12 to L3, and the right is slightly lower . The right kidney sits just below the diaphragm and posterior to the liver . The left sits below the diaphragm and posterior to the spleen . On top of each kidney is an adrenal gland . The upper parts of the kidneys are partially protected by the 11th and 12th ribs . Each kidney, with its adrenal gland is surrounded by two layers of fat: the perinephric fat present between renal fascia and renal capsule and paranephric fat superior to the renal fascia . </P> <P> The kidney has a bean - shaped structure with a convex and a concave border . A recessed area on the concave border is the renal hilum, where the renal artery enters the kidney and the renal vein and ureter leave . The kidney is surrounded by tough fibrous tissue, the renal capsule, which is itself surrounded by perirenal fat (adipose capsule), renal fascia, and pararenal fat (paranephric body). The anterior (front) surface of these tissues is the peritoneum, while the posterior (rear) surface is the transversalis fascia . </P>

Where are the kidneys on a human body