As part of the human excretory system, the female urinary system consists of special structures that rid the body of waste products of metabolism and maintain proper balance of salts and water in the blood as well as other body fluids. The kidneys, the major organs of the female urinary system, dispose of toxic wastes, such as urea, ammonia, and uric acid, as well as excess water, salts, and toxic chemicals in urine. These organs also monitor the quality of blood to prevent a person from being poisoned by the end products of his or her own metabolism. Other organs of the female urinary system include two ureters, the urethra, and the bladder. The urethra of the female urinary system is shorter than that of the male, opens between the legs, and performs only excretory functions, whereas the bladder of the female urinary system is connected to the anterior vaginal wall.
Waste products are constantly produced by the body because of chemical activity in the cells. It is, therefore, necessary to dispose of these waste products to prevent them from building up and poisoning the body. Excretion is the waste disposal process that is carried out by excretory organs that include the kidneys. Blood is processed by the kidneys through the excretion of wastes and the removal of excess water. Wastes and water form urine, a usually acidic fluid that is released from the body.
The 0.32 gallons (1.2 liters) of blood received per minute through the kidneys is processed by nephrons, the urine-forming units of the kidneys. Each of the human kidneys has about one million nephrons, and each nephron consists of a glomerulus, renal tubule, and renal capsule. In the glomerulus, a liquid is filtered from the blood into the renal capsule. This liquid, called filtrate, is composed of excess water and wastes, as well as beneficial substances such as vitamins and amino acids. Filtrate passes along the renal tubule, as the beneficial substances are released back into the blood while excess water and waste, or urine, is stored in the bladder.
Reabsorption of water that occurs mainly in the renal tubule is a process that is regulated by a hormone called the antidiuretic hormone. A hormone is a product of one body organ that controls activities in other organs. About 48 gallons (180 liters) of filtrate is filtered from the blood every day, but only 0.4 gallons (1.5 liters) is released as urine. Human kidneys process the entire blood supply of the body approximately 60 times a day. The storage organ, or the bladder, is emptied several times a day through a duct called the urethra.