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Assertion : Atria act as primer pumps th...

Assertion : Atria act as primer pumps that increase the ventricular pumping
Reason : About 80 precent of the blood flows directly through the atria into ventricles.

A

If both assertion and reason are true and reason is the correct explanation of assertion

B

If both assertion and reason are true but reason is not the correct explanation of assertion

C

If assertion is true but reason is false

D

If both assertion and reason are false

Text Solution

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The correct Answer is:
### Step-by-Step Solution: 1. **Understanding the Assertion**: The assertion states that the atria act as primer pumps that increase the ventricular pumping. This means that the atria play a crucial role in preparing the ventricles for effective pumping of blood. 2. **Understanding the Reason**: The reason provided is that about 80% of the blood flows directly through the atria into the ventricles. This indicates that the majority of blood entering the ventricles does so passively from the atria. 3. **Role of Atria in Heart Function**: The atria are the upper chambers of the heart. The right atrium receives deoxygenated blood from the body via the vena cava, while the left atrium receives oxygenated blood from the lungs via the pulmonary veins. 4. **Mechanism of Blood Flow**: During the cardiac cycle, when the ventricles are in systole (contracting), the atria are filling with blood. This allows for a continuous flow of blood into the ventricles. The atria prevent the interruption of venous return to the heart, ensuring that blood can flow smoothly into the ventricles. 5. **Importance of Atria**: If the atria were not functioning properly, the venous blood flow would become pulsatile rather than continuous. This would significantly reduce the efficiency of blood circulation and the overall output of the heart. 6. **Conclusion**: Both the assertion and the reason are correct. The atria do act as primer pumps, and the reason that about 80% of blood flows directly through them into the ventricles is a valid explanation for this assertion. ### Final Answer: Both the assertion and the reason are correct, and the reason is the correct explanation for the assertion. ---
### Step-by-Step Solution: 1. **Understanding the Assertion**: The assertion states that the atria act as primer pumps that increase the ventricular pumping. This means that the atria play a crucial role in preparing the ventricles for effective pumping of blood. 2. **Understanding the Reason**: The reason provided is that about 80% of the blood flows directly through the atria into the ventricles. This indicates that the majority of blood entering the ventricles does so passively from the atria. 3. **Role of Atria in Heart Function**: The atria are the upper chambers of the heart. The right atrium receives deoxygenated blood from the body via the vena cava, while the left atrium receives oxygenated blood from the lungs via the pulmonary veins. ...
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