Cells and transport proteins are physically prevented from passing through the filtration membrane. This has the following effect on filtration: Cells and transport proteins are physically prevented from passing through the filtration membrane. This has the following effect on filtration: increased osmotic pressure in the filtrate that draws plasma through the membrane decreased osmotic pressure in the filtrate that increases the amount of filtration increasing osmotic pressure in the glomerular capillaries that reduces the amount of filtration neutral change in osmotic pressure with no effect on filtration