Kidneys are bean shaped organs which are located near the middle of human back just below the ribs-cage. Often the left kidney is positioned up to an inch higher than the right kidney. Each kidney is about 4-5 inches long and about 2 inches thick, weighing 4-6 ounces in the average adult. The kidneys are coloured dark reddish brown because of the high degree of vascularity.
The kidneys filter 150-200 quarts of blood plasma out of the blood stream each day. Approximately 99% of this blood plasma (less of wastes) is re-absorbed by the kidneys to produce urine. Kidney play the role of trash collections, which automatically flows to bladder through tube called Ureters.
Human body uses food for energy , self repair and the waste in sent to the blood. Kidney remove these wastes, if not then these wastes would build up in the blood and damage human body. Every kidney contains about a million nephrons. These nephrons are tiny -units inside the Kidneys. The kidneys have two main functions. They filter Wastes from the bloodstream and regulate certain qualities of the bloodstream. Filtering wastes from bloodplasma
- The kidneys filter bloodplasma out of the blood stream and remove the undesirable substances to produce urine.
- Undesirable substances in bloodplasma include: Toxin, Metabolism wastes, Excess ingested water, Excess mineral salts.
The actual filtering takes place in the nephrons. In Nephron, Blood vessels, called capillaries, intertwine with tiny urine carrying tubes called tubules. These tubules receive a combination of waste materials and chemicals that human body can still use as kidneys measure out chemicals like Sodium Phosphorus & Potassium and release them back to the blood to return to the body.
Thus kidneys regulate the body level of these substances. The right balance of these substances is necessary for life, but excess can be harmful.
Apart from removing wastes, human kidney releases three important harmones:
A. ERYTHROPOIETIN, which stimulates the bones to make red blood cells.
B. Renin which regulates blood pressure.
C. Vitamin D – The active form of it helps to maintain calcium for bones and for normal chemical balance in body.