Sunday, February 21, 2010
[one human kidney]
The kidneys are bean-shaped organs, each about the size of a fist. They are located near the middle of the back, just below the rib cage, one on each side of the spine. The kidneys are sophisticated reprocessing machines. Every day, a person’s kidneys process all of the body's blood about 20 times. About 2 quarts of waste products and extra water are sifted out of blood each day. This becomes urine, which flows to the bladder through tubes called ureters. The bladder stores urine until releasing it through urination.
Wastes in the blood come from the normal breakdown of active tissues, such as muscles, and from food. The body uses food for energy and self-repairs. After the body has taken what it needs from food, wastes are sent to the blood. If the kidneys did not remove them, these wastes would build up in the blood and damage the body.
The actual removal of wastes occurs in tiny units inside the kidneys called nephrons. Each kidney has about a million nephrons. In the nephron, a glomerulus—which is a tiny blood vessel, or capillary—intertwines with a tiny urine-collecting tube called a tubule. The glomerulus acts as a filtering unit, or sieve, and keeps normal proteins and cells in the bloodstream, allowing extra fluid and wastes to pass through. A complicated chemical exchange takes place, as waste materials and water leave the blood and enter the urinary system.
At first, the tubules receive a combination of waste materials and chemicals the body can still use. The kidneys measure out chemicals like sodium, phosphorus, and potassium and release them back to the blood to return to the body. In this way, the kidneys regulate the body’s level of these substances. The right balance is necessary for life.
Total or nearly total and permanent kidney failure is called End-stage Renal Disease. If a person’s kidneys stop working completely, the body fills with extra water and waste products. This condition is called uremia. Hands or feet may swell. A person will feel tired and weak because the body needs clean blood to function properly.
Untreated uremia may lead to seizures or coma and will ultimately result in death.
There is a machine which engineers have invented to replace, to a limited extent, the kidneys. This machine is called a dialysis machine. It's about the size of a small cabinet. The patient must be attached to it for several hour sessions several times per week. People relying on dialysis generally survive five to ten years.
The Talmud mandates the following prayer following urination or defecation:
When he comes out from an outhouse says: 'Blessed is He who has formed man in wisdom and created in him many orifices and many cavities. It is fully known before the throne of Thy glory that if one of them should be [improperly] opened or one of them closed it would be impossible for a man to stand before Thee'. How does the blessing conclude? 'Who healest all flesh and doest wonderfully'.
Let's say that this blessing with the greatest intensity and enthusiasm. We should really cry tears of joy after each urination. Without kidneys, each one weighing about one third of a pound, life would be quite bleak at best.
Posted by jewish philosopher at 5:00 PM