117) Facultative water reabsorption depends on the presence of antidiuretic hormone. In the presence of ADH,the pores of the collecting tubule enlarge and the filtrate loses water by osmosis as it passes through the medullary regions of increasing osmolarity. Consequently, water is conserved and urine becomes concentrated. The water that passes through these regions is reabsorbed by the body in order to prevent dehydration. 118) Glomerular hydrostatic pressure is the chief force pushing water and solutes across the filtration membrane. The higher the glomerular hydrostatic pressure, the more filtrate is pushed across the membrane. Colloid osmotic pressure of plasma proteins in the glomerular blood, and capsular hydrostaticpressure exerted by fluids in the glomerular capsule, drive fluids back into the glomerular capillaries. Thenet filtration pressure equals glomerular hydrostatic pressure minus the sum of colloid osmotic pressure of glomerular blood and capsular hydrostatic pressure. 119) Renal cells also produce chemicals, some of which act locally as signaling molecules. These chemicals include prostaglandins (vasodilators and vasoconstrictors), which probably regulate GFR; nitric oxide, a potent vasodilator produced by the vascular endothelium; adenosine, which constricts renal vasculature; and endothelin, a vasoconstrictor that inhibits renin release. 120) Water-filled pores in water-permeable portions of the convoluted tubules such as the PCT. 121) Freshly voided urine is relatively sterile but if it is allowed to stand, bacteria begin to metabolize the ureasolutes to release ammonia and other smells depending on the person's diet. A fruity smell generally means there is a diabetes problem. 122) The symptoms indicate a kidney stone that has been passed into the ureter. Treatment would be IV therapy to flush the stone out, surgery, or ultrasound waves to shatter the calculi. The prognosis is for complete recovery. There is a possibility of kidney stones forming again. 123) This client would have a much higher glomerular hydrostatic pressure and would therefore lose more fluids than normal. Because of the threat of dehydration, the staff should make sure the client drinks plenty of water. 124) Harry is showing the symptoms of kidney inflammation. The smoky brown color of the urine indicates the presence of blood or bile. Kidney inflammations usually result from infections either of the lower urinary tract or, in Harry's case, from his earlier infection of a sore throat. The kidney inflammation is called either pyelitis (involves only the renal pelvis and calyces) or pyelonephritis (affects the whole kidney). 125) Proteinuria is a condition in which the permeability of the glomerular capillaries is increased to such an extent that large amounts of plasma proteins (mostly albumin) pass into the glomerular filtrate and are excreted in the urine. If the condition is severe, the loss of plasma proteins may decrease osmotic
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