Renal Artery Stenosis
- Renal Artery Stenosis Overview
- Renal Artery Stenosis Risk Factors and Causes
- Renal Artery Stenosis Signs and Symptoms
- Exams and Tests
- Renal Artery Stenosis Treatment
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Renal Artery Stenosis Overview
Aside from filtering blood and making urine, the kidneys have other functions. One such function is monitoring blood pressure (performed by special cells called macula densa). Using a chemical messenger called angiotensin, these cells can help adjust blood flow throughout the body and maintain normal blood pressure. The angiotensin acts by increasing muscle tone in small artery walls to help boost blood pressure. Angiotensin also stimulates the release of aldosterone, which helps the body retain sodium and water, increasing the amount of fluid within the blood vessels.
Most people with high blood pressure have essential hypertension (hyper=more + tension=pressure), meaning that the cause of the high blood pressure is unknown. However, one known cause of hypertension is renal artery stenosis (renal=kidney + stenosis=narrowing).
Each kidney gets its blood flow via a renal artery that arises from the aorta, the major blood vessel from the heart. If one of the renal arteries narrows, it may cause decreased blood flow to the kidney and to the macula densa (the specialized, blood-pressure sensing cells in the kidney). These cells falsely presume that this low blood flow is being experienced by the rest of the body and that overall blood pressure is too low. They respond by increasing secretion of angiotensin, triggering the body's response to increase blood pressure.
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Renal Artery Stenosis
Chronic Kidney Disease Overview
Normal Kidneys and Their Function
The kidneys are a pair of bean-shaped organs that lie on either side of the spine in the lower middle of the back. Each kidney weighs about ΒΌ pound and contains approximately one million filtering units called nephrons. Each nephron is made of a glomerulus and a tubule. The glomerulus is a miniature filtering or sieving device while the tubule is a tiny tube like structure attached to the glomerulus.
The kidneys are connected to the urinary bladder by tubes called ureters. Urine is stored in the urinary bladder until the bladder is emptied by urinating. The bladder is connected to the outside of the body by another tube like structure called the urethra.
The main function of the kidneys is to remove waste products and excess water from the blood. The kidneys process about 200 liters of blood every day and produce about two liters of urine. The waste products ar...
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Renal Artery Stenosis »
Specialists have known for a long time that renal artery stenosis (RAS) is the major cause of renovascular hypertension and that it may account for 1-10% of the 50 million people in the United States who have hypertension.
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