Now, if we sum all those individual forces in this particular region of the blood vessel and we divide it by the area of the walls of the blood vessel, within that particular section, we get our measurement called the blood pressure. Now, in our cardiovascular system we have different types of blood vessels. We have large and small arteries. We have large and small veins. We also have capillaries. Now the question is why is there a pressure variation between one location and a different location inside our blood vessel system?