In hemodialysis, which processes remove waste products and fluids?

In hemodialysis, which processes remove waste products and fluids?

• A. Osmosis; Diffusion
• B. Diffusion; Ultrafiltration
• C. Filtration; Adsorption
• D. Endocytosis; Active transport

Answer: (B)

Hemodialysis relies on two processes to remove wastes and fluids: diffusion and ultrafiltration. Diffusion moves dissolved solutes, like urea and creatinine, from the blood, where their concentration is higher, across the semipermeable membrane into the dialysate, where their concentration is lower. Ultrafiltration uses a hydrostatic pressure gradient to push water out of the blood across the membrane into the dialysate, removing excess fluid. Osmosis follows water movement along a gradient as well, but the amount of fluid removed in dialysis is controlled mainly by ultrafiltration, not osmotic flow. Adsorption to the membrane can remove some substances, but it’s not the primary mechanism for clearing wastes and fluids. Endocytosis and active transport are cellular processes not involved in the dialysis process.

Hemodialysis relies on two processes to remove wastes and fluids: diffusion and ultrafiltration. Diffusion moves dissolved solutes, like urea and creatinine, from the blood, where their concentration is higher, across the semipermeable membrane into the dialysate, where their concentration is lower. Ultrafiltration uses a hydrostatic pressure gradient to push water out of the blood across the membrane into the dialysate, removing excess fluid. Osmosis follows water movement along a gradient as well, but the amount of fluid removed in dialysis is controlled mainly by ultrafiltration, not osmotic flow. Adsorption to the membrane can remove some substances, but it’s not the primary mechanism for clearing wastes and fluids. Endocytosis and active transport are cellular processes not involved in the dialysis process.