The answer is that the strength of heart contraction and
blood volume. It is affected by blood volume, stroke volumes, total peripheral
resistance, and HR. It has Increase in any of these will increase blood
pressure. Vasoconstriction of arterioles raises blood pressure upstream in the
arteries
I believe blood pressure is determined by the strength of heart contraction and the blood volume. Blood flow and blood pressure are greatly influenced by the cardiac output, compliance, volume of the blood, viscosity of the blood, blood vessel length and diameter. Blood moves from higher pressure to low pressure. It is pumped from the heart into the arteries at high pressure. If you increase pressure in the arteries and cardiac function does not compensate, blood flow will actually decrease.
