The kidneys are reddish bean-shaped organs. There are usually two of them in the body on either side. They are located in the lower back near the twelfth rib. The function of the kidneys is to filter blood and remove waste materials while keeping the necessary nutrients in the blood. The kidneys are located within perirenal fat and renal fascia (connective tissue) that protect them against injury in case of blows from the outside. The outer part of the kidneys is the renal cortex and the darker part of the kidneys is called the renal medulla.
Within each kidney, the waste that will soon become urine travels through many structures before it reaches the ureter. The renal medulla contains triangular areas of tissue called the renal pyramids. Urine flows through a renal pyramid and exits at the renal papilla, which has small openings designed to allow urine to pass through to the renal pelvis, a widened area of the kidney. After the renal pelvis, the urine flows and exits through the ureter to the urinary bladder. When the bladder is full, the bladder sends signals to the brain that the body needs signaling urinary urge which is also called Micturition.
The kidneys are paired organs with several functions:
Renal Physiology - Study of Kidney Function
The kidneys receive blood from the paired renal arteries, and drain into the paired renal veins. Each kidney excretes urine into a ureter, itself a paired structure that empties into the urinary bladder.
Nephrology - the medical specialty concerned with kidney diseases.
Diseases of the kidney are diverse, but individuals with kidney disease frequently display characteristic clinical features:
When renal function is persistently poor, dialysis and kidney transplantation may be treatment options. If the kidneys are not properly treated, kidney failure complications can be deadly.