Pressure in blood capillaries must be greater than the pressure in arteries or veins. We know that the cross-section area of a pipe is inversely proportional to the pressure of the fluid flowing through it. Fluid flowing through a broad pipe will be at lower pressure and the fluid passing through a narrow pipe would be at a very high pressure. If we apply the same principle to the blood vessels of the circulatory system, then the pressure of blood inside the capillaries should be greater than the blood pressure inside the arteries. But, it is not so. This is because the number of capillaries is very high as compared to the arteries and thus the total area of capillaries is way more than the area of an artery. So, the pressure of blood in capillaries gets distributed and is thus very less as compared.