Amount of blood in hea
**Core Concept**
The amount of blood in the heart is an essential parameter in cardiology, which is typically measured in terms of stroke volume (SV) or cardiac output (CO). The stroke volume is the amount of blood pumped by the left ventricle of the heart in one contraction, while cardiac output is the total amount of blood pumped by the heart in one minute.
**Why the Correct Answer is Right**
The correct answer to this question is an estimate of the stroke volume, which is roughly 70 mL. This is because the human heart pumps approximately 70 mL of blood with each beat. The cardiac output, which is the total amount of blood pumped by the heart in one minute, is calculated by multiplying the stroke volume by the heart rate (in beats per minute). The average cardiac output in a resting adult is around 5 liters per minute.
**Why Each Wrong Option is Incorrect**
**Option A:** This value is too low, as it would indicate a severely compromised cardiac function.
**Option B:** This value is too high, as it would indicate an excessively high cardiac output, which could lead to cardiac failure.
**Option C:** This value is not a typical measurement for blood in the heart, as it refers to a different physiological parameter.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that cardiac output is the product of stroke volume and heart rate, and any increase in heart rate without a corresponding increase in stroke volume can lead to decreased cardiac efficiency and potentially to cardiac failure.
**Correct Answer:** D. 70 mL.