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Questions and Answers
What is the end-diastolic volume of the left ventricle?
What is the end-diastolic volume of the left ventricle?
How is stroke volume calculated?
How is stroke volume calculated?
What is the normal range for ejection fraction in a healthy individual?
What is the normal range for ejection fraction in a healthy individual?
What is the cardiac output of an individual with a stroke volume of 70 ml/beat and a heart rate of 70 beats/minute?
What is the cardiac output of an individual with a stroke volume of 70 ml/beat and a heart rate of 70 beats/minute?
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Which organ receives the largest amount of blood flow?
Which organ receives the largest amount of blood flow?
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What is the formula to calculate cardiac output?
What is the formula to calculate cardiac output?
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What does an ejection fraction measure?
What does an ejection fraction measure?
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Which organ receives the largest amount of blood flow?
Which organ receives the largest amount of blood flow?
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What is stroke volume?
What is stroke volume?
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How does cardiac output change during exercise?
How does cardiac output change during exercise?
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Study Notes
The Heart's Function
- Main role is to pump oxygenated blood with nutrients through arteries to tissues and return deoxygenated blood through veins.
Left Ventricle Characteristics
- End-diastolic Volume (EDV): At relaxation, approximately 120 milliliters of blood is present in the left ventricle.
- End-systolic Volume (ESV): After contraction, approximately 50 milliliters remain in the left ventricle.
- Stroke Volume (SV): Calculated as EDV minus ESV, resulting in a stroke volume of 70 milliliters per heartbeat.
Stroke Volume Variability
- Stroke volume can differ based on body size; 50 milliliters may be adequate for a small person but low for a larger individual.
Ejection Fraction
- Ejection Fraction (EF): Represents the percentage of blood pumped from the left ventricle per heartbeat, calculated as stroke volume (70 ml) divided by end-diastolic volume (120 ml), resulting in about 58%.
- Normal ejection fraction ranges between 50% and 65%. Below 50% indicates low contractility.
Cardiac Output
- Cardiac Output (CO): Total blood volume ejected by the left ventricle per minute, calculated by multiplying stroke volume by heart rate.
- Example: With a stroke volume of 70 ml/beat and heart rate of 70 beats/min, CO equals 4900 ml/min (4.9 liters/min).
- An adult body contains approximately 5 liters of blood, implying complete circulation through the left ventricle every minute.
- The heart can adapt both heart rate and stroke volume based on activity levels, with trained athletes achieving up to 35 liters/min.
Blood Distribution
- Cardiac output is distributed to organs based on their oxygen and nutrient needs.
- Liver: Receives the largest blood flow.
- Kidneys: Receive significant flow but less than the liver, yet display high tissue perfusion based on mass—more blood per gram than other organs.
- Distinction between flow (total blood volume over time to an organ) and perfusion (blood volume per gram of tissue over time).
Summary of Key Metrics
- Stroke Volume: Volume of blood pumped with each heartbeat (EDV - ESV).
- Ejection Fraction: Percentage of blood pumped out with each heartbeat; measure of contractility.
- Cardiac Output: Volume of blood pumped in one minute, calculated as stroke volume multiplied by heart rate.
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Description
This quiz covers the anatomy and function of the heart, specifically focusing on the left ventricle. Learn about the processes of blood circulation and the significance of the end-diastolic volume. Test your knowledge on cardiovascular physiology.
