What is the primary mechanism through which haemodialysis removes waste?

The primary mechanism through which haemodialysis removes waste is diffusion. In the process of haemodialysis, blood is circulated through a dialysis machine where it flows through a semipermeable membrane. This membrane allows small waste molecules and excess solutes, such as urea and creatinine, to move from the blood into the dialysis solution (dialysate) by the principle of diffusion.

Diffusion occurs as a result of a concentration gradient; waste products in the blood are at a higher concentration compared to the dialysate. As a result, these substances move from an area of higher concentration (the blood) to an area of lower concentration (the dialysate) until equilibrium is reached. This mechanism is crucial for the effective removal of toxins and excess ions, helping to maintain the body’s chemical balance in patients with kidney failure.

In contrast, filtration refers to the process by which larger particles or fluids are separated from smaller ones, which is not the primary mechanism in haemodialysis. Absorption involves the uptake of substances, which also does not accurately describe the functions of dialysis. Evaporation, while it is a physical process, does not pertain to the methods used in haemodialysis for waste removal. Thus