Calculate cardiac output

Question (3 marks): A patient has a stroke volume of 75 cm³ and a resting heart rate of 68 bpm. Calculate her cardiac output in cm³/min, then state what happens to cardiac output during exercise and why.

Mark scheme (3 marks):

• Cardiac output = stroke volume × heart rate = 75 × 68 ✓
• = 5100 cm³/min ✓ (accept 5.1 dm³/min or 5.1 L/min)
• During exercise cardiac output increases because heart rate rises (and stroke volume rises slightly) to deliver more oxygen and glucose to respiring muscles / remove CO₂ faster ✓

Max 3 marks.