Understanding Net Filtration Pressure
Net filtration pressure shows the final push that moves fluid across a membrane. In physics and physiology, it combines hydrostatic pressure with osmotic pressure. Hydrostatic pressure pushes fluid outward. Osmotic pressure pulls fluid toward dissolved particles. The balance decides whether fluid leaves a capillary, enters a capillary, or stays near equilibrium.
Why the Forces Matter
A positive result means filtration. Fluid is moving outward through the membrane. A negative result means absorption. Fluid is being pulled inward. A value close to zero means the opposing forces nearly cancel. This calculator lets you test each force separately. You can change capillary pressure, interstitial pressure, oncotic pressure, reflection coefficient, and filtration coefficient. That makes it useful for classroom work, renal examples, and membrane transport studies.
Using Results in Physics
The main pressure result is a driving pressure. It is measured in millimeters of mercury. The flow result multiplies this pressure by the filtration coefficient. A higher coefficient means the membrane allows more movement. A lower coefficient means the same pressure produces less flow. The reflection coefficient adjusts the osmotic effect. When it is one, solutes are fully reflected. When it is zero, osmotic pressure has little effect.
Interpreting Flow
Results should be read as model estimates. Real systems also depend on pore size, surface area, temperature, proteins, vessel shape, and measurement error. The range tool helps show uncertainty. Enter a possible pressure error to see high and low estimates. The chart separates outward forces and inward forces. This makes the result easier to explain. Use the example table to compare common cases. Then adjust the form values for your own problem. The CSV and PDF buttons help save the answer for reports, assignments, or lab notes.
A careful comparison is often more valuable than one final number. Small pressure changes can reverse the direction of flow. For that reason, the calculator labels the state and shows margins. It also keeps the equation visible. Students can connect each input with a physical role. This supports clear checking, better discussion, and faster revision before solving longer transport problems. You can also compare repeated trials without rewriting the full calculation again.