What are the kidneys and what do they do?
The kidneys are two bean-shaped organs, each about the size of a fist. They are located just below the rib cage, one on each side of the spine. Every day, the two kidneys filter about 120 to 150 quarts of blood to produce about 1 to 2 quarts of urine, composed of wastes and extra fluid. The urine flows from the kidneys to the bladder through two thin tubes of muscle called ureters, one on each side of the bladder. The bladder stores urine. The muscles of the bladder wall remain relaxed while the bladder fills with urine. As the bladder fills to capacity, signals sent to the brain tell a person to find a toilet soon. When the bladder empties, urine flows out of the body through a tube called the urethra, located at the bottom of the bladder. In men the urethra is long, while in women it is short.
Another word for kidney is renal. You may hear your doctor talk about renal function or read materials that mention renal failure. Whenever you see or hear the word renal, you will know the subject is about kidneys.
They kidneys have a couple of different functions. Their main purpose of the kidney is to separate urea, mineral salts, toxins, and other waste products from the blood, especially a nitrogen-containing compound called urea.
Pelvis of Kidney
The renal pelvis or pelvis of the kidney is the basin-like or funnel-like dilated proximal part of the ureter in the kidney. In humans, the renal pelvis is the point of convergence of two or three major calyces. Each renal papilla is surrounded by a branch of the renal pelvis called a calyx. The major function of the renal pelvis is to act as a funnel for urine flowing to the ureter. The renal pelvis is the location of several kinds of kidney cancer. Its mucous membrane is covered with transitional epithelium, and an underlying lamina propria of loose to dense connective tissue.
Renal Arteries and Veins
The renal arteries normally arise off the side of the abdominal aorta, immediately below the superior mesenteric artery, and supply the kidneys with blood. Each is directed across the crus of the diaphragm, so as to form nearly a right angle with the aorta.
The renal arteries carry a large portion of total blood flow to the kidneys. Up to a third of total cardiac output can pass through the renal arteries to be filtered by the kidneys.
The renal veins are veins that drain the kidney. They connect the kidney to the inferior vena cava. They carry the blood filtered by the kidney.
