NEPHRONS - The Kidneys' Filtration UnitNephrons are microscopic tube-like structures in the kidneys which filter the blood and cause wastes to be removed. They are the most basic structure of the kidney's anatomy, and are an integral part of the urinary system. Each kidney contains approximately one million of them.
While they may look like tangles of vessels and tubules, nephrons have an orderly structure, designed to perform the essential process of filtering the blood.The Glomerulus is the primary structure of the filtering process. It regulates the concentration of essential substances such as potassium, calcium, and hydrogen, and removes substances not produced by the body such as drugs and food additives. The Glomerulus is contained inside a cup-shaped structure known as the Bowman's capsule, from which extends the Renal tubule. This tubule makes a number of turns and loops and eventually leads to the Collecting tubule. The part of the renal tubule which loops around into a 'U' turn is called the Loop of Henle.
THE FILTERING PROCESS The major function of the kidney is to remove waste products from the blood and by extension, the body. Blood is supplied to the nephrons from a branch of the Renal Artery. It first goes to the Glomerulus. Water and other substances such as sugar or glucose, salt, amino acids and urea are removed from the blood (filtered). The substances extracted from the blood remain in the Bowman's Capsule... while the filtered blood moves along tiny vessels called Capillaries, and exits the kidney through the Renal Vein. The other substances which are not useful to the body, such as excess water and salt,urea, uric acid... continues to move along the renal tubule into the Collecting tubule. These waste products form what is known as urine. From the Collecting tubule the waste products go to the ureter then into the bladder... then eventually expelled from the body (as urine). In Summary, the main function of nephrons is to filter water, urea, salt, glucose, amino acids and other trace substances from the blood. Many of the filtered materials are then reabsorbed into the blood to be reused by the body, to maintain normal body functions. The waste materials remain behind to be excreted as waste products in the urine. If you understand the function of the nephrons, you will have a good understanding of the main function of the kidneys. These microscopic structures not only keep the body's chemistry clean, they also help to ensure that the correct concentration of the blood is maintained.
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