The urinary system is the drainage system which consists of organs involved with the removal of wastes from the body.
The kidneys are located in the back of the abdomen, one on each side of the spine and surrounded by a mass of fat and loose areolar tissue.
Each kidney is about 4-5 inches long and functions to filter the blood by removal of the wastes, control the body’s fluid balance, and regulate the balance of electrolytes.
The ureters are a pair of tubes which carry the urine from the kidneys to the urinary bladder. Each ureter proper measures about 8-10 inches long. The thick-walled narrow cylindrical tube has smooth muscles that regularly contract and relax to force urine into the bladder.
The urinary bladder is a musculoskeletal sac which acts as a reservoir for the urine. It receives urine from the kidneys through the ureters and is dispensed from the bladder through the urethra.
When the bladder is moderately full it contains about 0.5 liters and assumes an oval form. The bladder capacity decreases with old age.
As the bladder fills with urine, you may notice a feeling that you need to urinate.