There is a filtration membrane in the glomerulus, on one side are capillaries, which contain blood, and on the other side is the lumen of the renal capsule, in which urine is formed. The water in the blood passes through the filtration membrane and penetrates to the other side to form urine, while the blood will be pressurized in the process of penetrating to the other side, which is called the effective filtration pressure of the glomerulus. There are many factors affecting the effective glomerular filtration pressure, such as the pressure within the glomerular capillaries, the concentration of protein in the plasma, and the pressure within the lumen of the renal capsule. The higher the pressure in the glomerular capillaries, the higher the filtration pressure; the protein in the blood is like a sponge that absorbs water, if the concentration is low, the water can not be absorbed in the blood vessels, which will cause an increase in the effective filtration pressure; and the higher the pressure in the lumen of the renal capsule, the stronger the blockage of water, which will lead to a smaller filtration pressure.