Final answer:
Peritoneal dialysis uses osmosis to filter toxins from the blood, where an osmotic gradient across a semipermeable membrane allows small solute molecules like urea to pass through, while larger molecules are retained.
Step-by-step explanation:
The process by which peritoneal dialysis filters toxins from the blood is primarily osmosis. Peritoneal dialysis involves a dialysate solution that is used to absorb waste products from the blood by creating an osmotic gradient across a semipermeable membrane. Unlike hemodialysis, which also utilizes diffusion but typically occurs in a medical facility, peritoneal dialysis can be performed at home. The semipermeable membrane of the peritoneal cavity allows small solute molecules like urea to pass through while preventing larger molecules like red blood cells from passing. The dialysate solution in peritoneal dialysis has a lower concentration of solutes compared to the blood, causing water and wastes like urea to move from the blood to the dialysate, cleansing the blood.