Urine Production
The kidneys are two bean-shaped organs located below the rib cage, one on each side of the spine. Kidneys play a major role in the body's daily urinary elimination. The body produces one to two liters of urine a day during the process of removing waste products from the blood, according to the book "Basic Nursing," by Patricia Potter and Anne Perry. The National Kidney and Urologic Diseases Information Clearinghouse says that the kidneys process nearly 200 quarts of blood in a day, sorting out around two quarts of waste and excess water from the body. The kidneys can remove waste products efficiently because they have a high amount of blood flow, nearly 25 percent of the body's cardiac output, according to Potter and Perry. The waste and excess water combination becomes urine and flows through the ureters into the bladder. The bladder is the holding area for urine until it is expelled through the urethra.
Nephrons and Glomerulus
The functional units of the kidneys are the nephons, where the waste removal and water regulation take place. Electrolyte concentration is also controlled by the nephrons. Each kidney has close to one million tiny nephrons. Water and inorganic electrolytes such as potassium, sodium, calcium, chloride, magnesium, phosphate, sulfate and hydrogen are reabsorbed in the kidneys, according to the American Heart Association.
The initial site of urine formation is in the glomerulus, a cluster of capillaries, which can be found in the nephron, says Potter and Perry. Glomerulus is responsible for filtering water, glucose, urea, amino acids, creatinine and uric acid. Protein is not filtered through the glomerulus; therefore, protein in the urine, proteinuria, is an indicator of a problem in the glomerulus. Nearly 99 percent of the filtrate from the glomerulus is reabsorbed.
Blood Pressure Regulation
Blood pressure regulation is a major part of kidney function. Kidneys regulate fluids in the body that are related to blood volume and blood pressure, according to the American Heart Association. The kidneys' ability to excrete excess sodium chloride and extracellular fluid and blood pressure depends on regulating blood pressure to a normal level. One common cause of high blood pressure, also known as hypertension, is kidney disease, according to the American Heart Association. Any outside factors that interfere with the kidneys' ability to excrete salt from the body can cause blood pressure to increase, because excess fluids in the body result.
References
- National Kidney and Urologic Diseases Information Clearinghouse: The Kidneys and How They Work
- American Heart Association: Kidneys and Kidney Function
- "Basic Nursing"; Patricia Potter and Anne Perry; 2003
