Ultrafiltration is influenced by

Ultrafiltration is influenced by

• A. Hydrostatic pressure
• B. Transmembrane pressure
• C. Osmotic gradient
• D. Membrane pore size

Answer: (B)

Ultrafiltration is driven by the pressure difference across the dialysis membrane, and the key driving force is the transmembrane pressure. This transmembrane pressure represents the net push of water from the blood side to the dialysate side; it combines the pressures on the blood and dialysate sides and the also opposing influence of the blood’s protein (oncotic) pressure. When TMP is higher, more water is pushed out of the blood across the membrane, increasing ultrafiltration; when TMP is lower, the rate decreases. Hydrostatic pressure on the blood side contributes to TMP, but it’s the overall transmembrane pressure that truly governs the water-removal rate. The osmotic gradient, created by plasma proteins, can oppose filtration, reducing ultrafiltration, but it’s not the primary driving force. Membrane pore size matters for what can pass and how easily, yet the immediate rate of ultrafiltration is controlled by the pressure difference across the membrane, i.e., the transmembrane pressure.

Ultrafiltration is driven by the pressure difference across the dialysis membrane, and the key driving force is the transmembrane pressure. This transmembrane pressure represents the net push of water from the blood side to the dialysate side; it combines the pressures on the blood and dialysate sides and the also opposing influence of the blood’s protein (oncotic) pressure. When TMP is higher, more water is pushed out of the blood across the membrane, increasing ultrafiltration; when TMP is lower, the rate decreases.

Hydrostatic pressure on the blood side contributes to TMP, but it’s the overall transmembrane pressure that truly governs the water-removal rate. The osmotic gradient, created by plasma proteins, can oppose filtration, reducing ultrafiltration, but it’s not the primary driving force. Membrane pore size matters for what can pass and how easily, yet the immediate rate of ultrafiltration is controlled by the pressure difference across the membrane, i.e., the transmembrane pressure.