I know, I know this is probably a question too simple to be asked on a forum like biology stack exchange. Problem is, I looked many places and can't seem to find a more mathematical approach to explain why the contraction of a BV leads to increased blood pressure (BP). The main formula i'm looking at is Flow = Pressure/Resistance. In addition, Flow = Area x velocity so Area x velocity = Pressure/Resistance. As the BV constricts, the radius, ie. area, decreases, and so the pressure decreases. But clearly, that is not the case.
What am I missing here?