| There are two kidneys, each about the size of a fist, located on either side of the spine at the approximately waist height. |
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They perform following functions:
1. Remove waste products from the body and balance the body's fluids. |
| Each kidney contains up to a million functioning units called nephrons. A nephron is made up of a filter called glomerulus and a tubule. In the glomerulus waste products are filtered out while in the tubule, chemicals and water are either added to or removed from this filtered fluid according to the body's needs. The final product is the urine. The kidneys perform this life-sustaining job of balancing the body’s fluids and its composition so well that despite wide variation in our food and liquid intake, the body water and composition remains constant. For example, if we drink 10 liters of water a day, the kidneys will produce 10 liters of urine and if we drink only 0.5 liter of water, only that much urine will be formed. Similarly, variation in salt intake will be matched by appropriate variation in salt excretion by the kidneys to maintain a constant level of salt in blood. The urine we excrete is stored in the bladder for anywhere from 1 to 8 hours. |
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| 2. Release hormones that regulate blood pressure |
| Kidneys produce a hormone called rennin which plays an important role in controlling blood pressure. |
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| 3. Control the production of red blood cells and thus prevent anemia. |
| They produce a hormone called erythropoietin which plays an important role in the formation of red blood cells (RBC). When the production of this hormone is decreased, the RBC production is decreased leading to anemia. Thus, when the kidneys fail, no matter how much iron and vitamins one takes, the anemia will not improve. |
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| 4. Makes our bones strong and healthy. |
| The kidneys activate vitamin D. For vitamin D to regulate calcium absorption from the diet and help bone formation, it has to be activated in the liver and the kidney. Therefore, when kidneys fail, vitamin D cannot be activated and the bones become weak. In fact, weak bones may be the first sign of kidney disease in growing children.. |
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