These forces play different roles depending on the structure being crossed. Both influence passage across capillary walls however only osmotic pressure influences that movement across cell membranes. The reason hydrostatic pressure has little influence over the transport across cell membranes is that the hydrostatic pressure of the intracellular and interstitial fluid is relatively constant. | These forces play different roles depending on the structure being crossed. Both influence passage across capillary walls however only osmotic pressure influences that movement across cell membranes. The reason hydrostatic pressure has little influence over the transport across cell membranes is that the hydrostatic pressure of the intracellular and interstitial fluid is relatively constant. |