Venae cavae open into

Options

A. Right auricle
B. Left auricle
C. Sinus venosus
D. Truncus arteriosus

Answer

**Step-by-Step Solution:**

1. **Understanding the Vena Cavae**: The vena cavae consist of two major veins: the superior vena cava and the inferior vena cava.

2. **Function of the Vena Cavae**: The superior vena cava collects deoxygenated blood from the upper parts of the body (head, neck, arms), while the inferior vena cava collects deoxygenated blood from the lower parts of the body (legs, abdomen).

3. **Opening into the Heart**: Both the superior and inferior vena cavae open into the right auricle (right atrium) of the heart.

4. **Atrial Diastole**: This process occurs during atrial diastole, which is the relaxation phase of the heart when the right auricle is filling with blood. The pressure in the right auricle is low, allowing blood to flow in from the vena cavae.

5. **Blood Flow After the Right Auricle**: Once the right auricle is filled with deoxygenated blood, it contracts and sends this blood into the right ventricle. From the right ventricle, the blood is then pumped into the pulmonary artery to be sent to the lungs for oxygenation.

6. **Conclusion**: Therefore, the correct answer to the question "Venae cavae open into" is the right auricle.

**Final Answer**: The venae cavae open into the right auricle.

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