Question

The stroke volume of a normal human heart is approximately:

• A. \(30\) mL
• B. \(50\) mL
• C. \(70\) mL
• D. \(100\) mL

Hint:

Cardiac Output (\(CO\)) is Stroke Volume (\(70\) mL) multiplied by Heart Rate (\(72\) bpm), which equals roughly \(5040\) mL/min or \(5\) liters per minute.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Stroke volume is the volume of blood ejected by each ventricle during a single heart beat. It is a critical measure of the heart's pumping efficiency.
Key Formula or Approach:
Stroke Volume (\(SV\)) is calculated as the difference between the End-Diastolic Volume (\(EDV\)) and the End-Systolic Volume (\(ESV\)):
\[ SV = EDV - ESV \]

Step 2: Detailed Explanation:
In a healthy resting adult:
1. The End-Diastolic Volume (volume of blood in the ventricle just before contraction) is about \(120\) mL.
2. The End-Systolic Volume (volume of blood remaining after contraction) is about \(50\) mL.
3. Therefore: \( SV = 120\text{ mL} - 50\text{ mL} = 70\text{ mL} \).
This means that in every beat, each ventricle pumps out about \(70\) mL of blood.

Step 3: Final Answer:
The approximate stroke volume is \(70\) mL.