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. Everyday, the two kidney filter about 120 to 150 quarts of blood to produce about 1 to 2 quarts of urine, composed of wastes and extra fluid.
FUNCTIONS OF THE KIDNEY
1. IT REGULATES FLUID VOLUME
The kidneys maintain our body's water balance ny controlling the water concerntration of blood plasma. Water that is not put back into the blood is excreted in our urine.
2. IT REGULATES OSMOLARITY OF THE BLOOD
Anti- diuretic hormone (ADH) is a hormone in the kidney that plays a major role in lowering osmolarity (reducing sodium concerntration) by increasing water reabsorption in the kidneys, thus helping to dilute bodily fluids. To prevent osmolarity from decreasing below normal, the kidneys also have a regulated mechanism for reabsorbing sodium in the distal nephron.
3.IT REGULATES ION CONCERNTRATION IN THE BLOOD
The kidneys work to keep certain ions in the body within their normal ranges needed by the body. Example of ions include; Na+, K+, Cl-, Ca2+ .
4. IT REGULATES BLOOD PH
The kidneys have two important roles in maintaining the acid- base balance; They reabsorb carbonic acid in the tubule, increasing or reducing acid secretion. So, urine that is more acidic than normal may mean the body is ridding itself of excess dietary acid and thus making blood pH more alkaline. They also excrete hydrogen ions into urine.
5. PRODUCTION OF HORMONES
The kidneys secrete a variety of hormones; including erythropoietin, calcitriol and renin. Erythropoietin is released in response to hypoxia (low levels of oxygen at tissue level) in the renal circulation. It stimulates erythropoiesis (production of red blood cells) in the bone marrow. Calcitriol, the activated form of vitamin D, promotes intestinal reabsorption of calcium and renal reabsorption of phosphate. Renin is an enzyme which regulates angiotensin and aldosterone levels.
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