Urinary Tract Anatomy - Children's Hospital Boston

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Urinary Tract Anatomy

Programs that treat this condition

	General Renal Consultation Program		Vesicoureteral Reflux Program
	Kidney Transplant Program		Gender Management Service (GeMS) Clinic

How does the urinary system work?

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The body takes nutrients from food and converts them to energy. After the body has taken the food that it needs, waste products are left behind in the bowel and in the blood.

The urinary system keeps chemicals, such as potassium and sodium, and water in balance by removing a type of waste called urea from the blood. Urea is produced when protein, found in meat products, is broken down in the body. Urea is carried in the bloodstream to the kidneys.

Other important functions of the kidneys include blood pressure regulation, and the production of erythropoietin, which controls red blood cell productions in the bone marrow.

Urinary system parts and their functions:

two kidneys - a pair of purplish-brown organs located below the ribs toward the middle of the back. Their function is to:

remove liquid waste from the blood in the form of urine.

keep a stable balance of salts and other substances in the blood.

produce erythropoietin, a hormone that aids the formation of red blood cells.

two ureters - narrow tubes that carry urine from the kidneys to the bladder. Muscles in the ureter walls continually tighten and relax forcing urine downward, away from the kidneys. If urine backs up, or is allowed to stand still, a kidney infection can develop. About every 10 to 15 seconds, small amounts of urine are emptied into the bladder from the ureters.
bladder - a triangle-shaped, hollow organ located in the lower abdomen. It is held in place by ligaments that are attached to other organs and the pelvic bones. The bladder's walls relax and expand to store urine, and contract and flatten to empty urine through the urethra.
two sphincter muscles - circular muscles that help keep urine from leaking by closing tightly like a rubber band around the opening of the bladder.
nerves in the bladder - alert a person when it is time to urinate, or empty the bladder.
urethra - the tube that allows urine to pass outside the body. The brain signals the bladder muscles to tighten, which squeezes urine out of the bladder. At the same time, the brain signals the sphincter muscles to relax to let urine exit the bladder through the urethra. When all the signals occur in the correct order, normal urination occurs.
Ureteropelvic junction (UPJ) - the transition point from the renal pelvis to the upper ureter. This is a common site of congenital urine flow obstruction that leads to hydronephrosis (dilation of the renal pelvis).
Ureterovesical junction (UVJ) - the transition point from the ureter to the bladder. This is another common site of congenital urine flow obstruction.



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