What is the correct expression for mean arterial pressure in terms of cardiac output and systemic vascular resistance?

• A. MAP = HR × SV
• B. MAP = CO ÷ TPR
• C. MAP = SBP - DBP
• D. MAP = CO × TPR

Answer: (D)

The main idea is that mean arterial pressure reflects the driving pressure for blood flow through the systemic circulation, determined by how much blood the heart pumps and how much resistance the vessels offer. Cardiac output is the volume the heart ejects each minute (heart rate times stroke volume), and systemic vascular resistance is the overall resistance in the systemic arteries. Applying the flow–pressure relationship here, MAP equals CO multiplied by TPR. This means when the heart pumps more blood or the vessels constrict (increasing resistance), MAP rises to push blood through the body. The other options mix up these relationships: HR × SV is CO, not MAP; CO ÷ TPR would imply the opposite effect of resistance on pressure; SBP minus DBP is the pulse pressure, not mean arterial pressure. So the correct expression is MAP = CO × TPR.