In order to understand blood pressure, you must first be familiar with the term blood flow. Blood flow is the volume of blood that flows past a certain point in the cardiovascular system during a specified amount of time. An example of this can be demonstrated at a gas station. Imagine you’re using the gas hose to fill up a car. The car has a 20 gallon gas tank. Let’s say that you fill it up in five minutes. You have measured the amount of gas that moved through the gas hose during a period of time (5 minutes). This means that the gas pump has a gasoline flow of 20 gallons per 5 minutes (or 4 gallons / 1 minute). This also means that any point in the hose is going to have the same gasoline flow as the nozzle, 4 gallons / 1 minute.

The cardiovascular system works in much the same way. If we measured the blood flow from the heart into the aorta, we can assume that it is the same amount as what we would find if we measured the total blood flow through the lungs, left heart, right heart, and the systemic circulation.

The driving force behind blood flow is blood pressure. Blood pressure is a measurement of the horsepower that drives the blood throughout our bodies. In order to explain this more clearly, I will use a car’s tire as an example. When you puncture a tire, the air rushes outward because the pressure is greater inside the tire. The same goes for the differences in blood pressure within our circulatory system. The blood will flow out of the higher pressure zone. It doesn’t flow due to a given pressure, but instead due to the pressure gradient, or pressure difference between two points. Less