Question

If the stroke volume of the heart is \(70\ \text{mL/beat}\) and the cardiac output is \(5250\ \text{mL/min}\), what is the heart rate?

• A. \(60\) beats/min
• B. \(70\) beats/min
• C. \(75\) beats/min
• D. \(80\) beats/min

Hint:

Cardiac Output = Stroke Volume × Heart Rate. A normal resting heart rate in adults is typically around \(70-75\) beats per minute.

Answer 1

The Correct Option is C

Concept: Cardiac Output (CO) is the volume of blood pumped by each ventricle per minute. It is given by the formula: \[ CO = SV \times HR \] where \(CO\) = Cardiac Output, \(SV\) = Stroke Volume (blood pumped per beat), \(HR\) = Heart Rate (beats per minute).

Step 1: Write the given values. \[ SV = 70\ \text{mL/beat} \] \[ CO = 5250\ \text{mL/min} \]

Step 2: Use the cardiac output formula. \[ CO = SV \times HR \] Substitute the values: \[ 5250 = 70 \times HR \]

Step 3: Solve for heart rate. \[ HR = \frac{5250}{70} \] \[ HR = 75\ \text{beats/min} \]