What plays a determining role in systolic blood pressure?

Systolic blood pressure is primarily influenced by cardiac output, which is the volume of blood the heart pumps per minute. When cardiac output increases, it usually leads to an increase in systolic blood pressure. This relationship occurs because as more blood is ejected from the heart with each beat, there is a greater force exerted on the walls of the arteries, resulting in higher pressure.

In contrast, while heart rate does contribute to cardiac output (as cardiac output is the product of stroke volume and heart rate), it is the volume of blood being pushed through the arteries that directly impacts systolic pressure. Peripheral resistance relates to the resistance against which the heart must pump, affecting diastolic pressure more prominently, whereas venous return pertains to blood returning to the heart rather than the blood being pumped out. Therefore, the most direct and significant factor determining systolic blood pressure is indeed cardiac output.