What determines your blood pressure?

Contract between blood and the walls of the blood vessels causes friction, and this impedes the flow of blood. This is called peripheral resistance. The arterioles and capillaries offer a greater total surface area, resisting flow more, slowing the blood down and causing the blood pressure to fall. The greatest drop in pressure occurs in the arterioles. The fluctuations in pressure in the arteries are caused by contraction and relaxation of the heart. As blood is expelled from the heart, pressure is higher. During diatole, elastic recoil of the blood vessels maintains the pressure and keeps blood flowing.

If the smooth muscles in the walls of an artery or arteriole contract, the vessels constrict, increasing resistance. In turn,…