Which factor is most accurate regarding the variables that the cardiovascular system can alter to maintain blood pressure?

Which factor is most accurate regarding the variables that the cardiovascular system can alter to maintain blood pressure?

• A. Blood viscosity
• B. Heart rate only
• C. Stroke volume only
• D. Heart rate, stroke volume and resistance

Answer: (D)

Blood pressure is set by how much blood the heart pumps and how much resistance the arteries offer. To keep BP steady, the body can adjust three main components: heart rate, stroke volume, and vascular resistance. Cardiac output, which drives pressure, equals heart rate times stroke volume, so increasing either heart rate or stroke volume raises BP, while lowering them lowers BP. At the same time, changing the tone of the arteries alters systemic vascular resistance: vasoconstriction raises resistance and pressure, vasodilation lowers it. The body uses sensors like baroreceptors to make these quick adjustments and maintain blood pressure within a target range. Blood viscosity can influence overall resistance, but it is not rapidly adjustable in the moment-to-moment regulation of BP, so it isn’t a primary acute control variable.

Blood pressure is set by how much blood the heart pumps and how much resistance the arteries offer. To keep BP steady, the body can adjust three main components: heart rate, stroke volume, and vascular resistance. Cardiac output, which drives pressure, equals heart rate times stroke volume, so increasing either heart rate or stroke volume raises BP, while lowering them lowers BP. At the same time, changing the tone of the arteries alters systemic vascular resistance: vasoconstriction raises resistance and pressure, vasodilation lowers it. The body uses sensors like baroreceptors to make these quick adjustments and maintain blood pressure within a target range. Blood viscosity can influence overall resistance, but it is not rapidly adjustable in the moment-to-moment regulation of BP, so it isn’t a primary acute control variable.