Biology Forums - Study Force

GFR is influenced by multiple factors, like those seen at tissue capillary beds. Recall that filtration occurs as pressure forces fluid and solutes through a semipermeable barrier with the solute movement constrained by particle size. Hydrostatic pressure is the pressure produced by a fluid against a surface. The blood inside the glomerulus creates glomerular hydrostatic pressure which forces fluid out of the glomerulus into the glomerular capsule. The fluid in the glomerular capsule creates pressure pushing fluid out of the glomerular capsule back into the glomerulus, opposing the glomerular hydrostatic pressure. This is the capsular hydrostatic pressure. These fluids exert pressures in opposing directions. Net fluid movement will be in the direction of the lower pressure. However, the concentration of the solutes in the fluids affects net movement of fluid as well.