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3.11 gather, process and analyse information from secondary sources to compare the process of renal dialysis with the function of the kidney

gather, process and analyse information from secondary sources to compare the process of renal dialysis with the function of the kidney

Summary: Comparison of the process of renal dialysis with the function of the kidney

Dialysis means separation in Greek, and, like the nephrons of the kidney, the dialysis machine separates molecules from the blood removing some and returning others. The patient’s blood is pumped from an artery through tubes made of selectively permeable membrane. The artificial tubing allows only water and small solute molecules to pass through it into a dialysing solution that surrounds the tube. This dialysing solution is similar to the interstitial fluid found around nephrons. As the blood circulates through the dialysis tubing, urea and excess salts diffuse out of it instead of leaving by pressure filtration, as in the nephron. Those substances needed by the body, such as bicarbonate ions (HCO3 – ) diffuse from the dialysing solution into the blood (reabsorption). The machine continually discards used dialysing solution as wastes build up in it.

Two healthy kidneys filter the blood volume about once every half-hour. Dialysis is a much slower and less efficient process than the natural processes found in a healthy kidney but it is a lifesaver for those people with damaged kidneys.