Heart rate, stroke volume and cardiac output at rest

Overview

Resting heart rate, stroke volume and cardiac output, the equation that links them, the thicker left ventricle, worked pulse and cardiac output calculations, and why trained and untrained performers share a resting cardiac output.

What you need to know

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Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Define heart rate and give a typical resting value.

   Model answer

   Heart rate is the number of times the heart beats per minute. A typical resting value for an untrained adult is about 70–72 bpm.

2. 2

   Define stroke volume and give a typical resting value.

   Model answer

   Stroke volume is the volume of blood pumped out of the left ventricle in each contraction. A typical resting value is about 70 ml.

3. 3

   Define cardiac output and give a typical resting value.

   Model answer

   Cardiac output is the volume of blood pumped out of the left ventricle each minute. The typical resting value is about 5 L/min.

4. 4

   State the equation linking cardiac output, stroke volume and heart rate.

   Model answer

   Cardiac output equals stroke volume multiplied by heart rate. The equation is Q = SV × HR.

5. 5

   Why does the left ventricle have a thicker wall than the right ventricle?

   Model answer

   The left ventricle pumps oxygenated blood through the aorta to the whole body. The thicker muscular wall generates the higher pressure this needs.

6. 6

   A performer's pulse is counted as 18 beats in 15 seconds. What is the resting heart rate?

   Model answer

   The resting heart rate is 72 bpm. The count × 4 gives 18 × 4 = 72 beats per minute.

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