The kidneys perform several important functions that are vital to maintaining a healthy body. They produce vitamin D, which is needed for bone health. They secrete a hormone that increases the production of red blood cells. The kidneys eliminate waste products, which prevents the buildup of toxic substances in the body. The kidneys play an important role in regulating acids, bases and electrolytes within the body as well.
Vitamin D Production
Douglas Eaton, professor of physiology at Emory University School of Medicine, explains in “Vander’s Renal Physiology” that the kidneys make the active form of vitamin D, which is essential for strong and healthy bones. They perform this function when they are directed to do so by the parathyroid gland. This gland secretes a hormone that gives instructions to both the kidneys and the bones. In response, the kidneys hold onto more calcium, send more phosphate to the urine and make vitamin D.
Erythropoietin Secretion
Erythropoietin, or EPO, is a hormone secreted by the kidneys. If the oxygen levels in the bloodstream or within the kidneys decrease for any reason, the kidneys release EPO. This hormone stimulates the bone marrow to make red blood cells. The increase of red blood cells in turn increases the volume of blood and the oxygen level, because red blood cells carry oxygen.
Elimination of Waste
Another important function of the kidneys is the elimination of waste from the body. The metabolism that takes place in cells throughout the body creates waste products, according to Frederic Martini, Ph.D., in “Fundamentals of Anatomy and Physiology.” The breakdown of proteins creates urea. The daily recycling of RNA, genetic material found in cells, creates a substance called uric acid. The skeletal muscles break down creatine phosphate, a substance that the muscles use for energy. The breakdown of creatine phosphate creates creatinine. The kidneys filter these waste products from the blood and produce the urine that eliminates them from the body.
Blood pH Regulation
One of the main functions of the kidneys is to keep a balance in the blood between acids and bases. The level of acidity or basicity in the blood is its pH. If the blood becomes too acidic it can cause growth problems, bone abnormalities, kidney disease and kidney failure. Researcher Elizabeth Corwin writes in “Handbook of Pathophysiology” that each kidney has about one million structures called nephrons. A nephron is made up of long tubules and capillaries. As the blood passes through these tubules, the kidneys restore the balance between acids and bases while removing waste products.
Regulating Electrolytes
Electrolytes are minerals in the bloodstream—such as sodium, potassium, chlorine and magnesium—that have an electric charge. Electrolytes are critical for muscle and cell functioning, and electrolyte imbalances can have serious health consequences. “Vander’s Renal Physiology” explains that the kidneys help to regulate these electrolytes. Just as they keep a balance between acids and bases, they balance electrolytes as well.
