c c c Ôm Two pathophysiologic mechanisms have been proposed for the development of hypertensive nephrosclerosis. One mechanism suggests that glomerular ischemia causes hypertensive nephrosclerosis. This occurs as a consequence of chronic hypertension resulting in narrowing of preglomerular arteries and arterioles, with a consequent reduction in glomerular blood flow. Alternatively, glomerulosclerosis occurs because of glomerular hypertension and glomerular hyperfiltration. According to this theory, hypertension causes some glomeruli to become sclerotic. As an attempt to compensate for the loss of renal function, the remaining nephrons undergo vasodilation of the preglomerular arterioles and experience an increase in renal blood flow and glomerular filtration. The result is glomerular hypertension, glomerular hyperfiltration, and progressive glomerular sclerosis. These mechanisms are not mutually exclusive, and they may operate simultaneously in the kidney. NEPHROSCLEROSIS Ôm Hardening of the walls of the small arteries and arterioles (smallarteries that convey blood from a rteries to the even smallercapillaries) of the kidney. This condition is caused by hypertension.Hyp ertension can be present in a person for20 to 30 years without evidence of kidney involvement; su chpersons usually die of other effects of hypertension such ascongestion of blood in the heart, har dening of the heart tissue, orcerebral (brain) hemorrhage. If these maladies do not occur first, there is usually some eventual renal (kidney) involvement.Nephrosclerosis is classified as either b enign or malignant.
RENAL ANATOMY AND PHYSIOLOGY Ôm The kidneys are bean-shaped organs that sit in the back of the lower abdominal cavity on either side of the spinal cord. The organs are cushioned by perinephric fat, fatty tissue that surrounds the kidneys and adrenal glands to prevent damage and movement in the abdominal cavity. Under normal conditions, humans are born with two kidneys, but it is possible to survive with only one as long as disease or other factors do not strain the organ. Ôm èidney Function: The main function of the kidney is to maintain the fluid, electrolyte, and pH balance of the body by filtering ions, macromolecules, water, and nitrogenous wastes from the blood based on the body¶s condition. Wastes filtered out of the blood drains from canals in the kidney into the bladder as urine. A loss of kidney function results in the need for dialysis, which is an artificial method of removing wastes from the blood by running the blood from the body, through an artificial kidney, and then back into the body. Ôm Renal Anatomy: The kidneys are situated in the perinephric fat but are also surrounded by a tough fibrous layer of connective tissue called the fibrous renal capsule. The hilus of the kidney is the central indent that gives the bean shape to the organ, and it is where the artery carrying oxygenated blood enters, and the ureter carrying urine exits, the kidney. Within the kidney, the renal artery branches into smaller blood vessels.
