Right atrium of heart of mammal receives blood from

Options

A. Sinus venosus
B. Pulmonary veins
C. Pulmonary aorta
D. Precaval vein and postcaval vein

Answer

To answer the question about where the right atrium of a mammal's heart receives blood from, we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding the Structure of the Heart**:
- The heart consists of four chambers: the right atrium, left atrium, right ventricle, and left ventricle. The right atrium is the chamber that receives deoxygenated blood.

2. **Identifying Blood Vessels**:
- The right atrium receives blood from two main veins: the superior vena cava and the inferior vena cava.
- The **superior vena cava** brings blood from the upper parts of the body (head, neck, arms).
- The **inferior vena cava** brings blood from the lower parts of the body (legs, abdomen).

3. **Flow of Blood**:
- Blood enters the right atrium from these two veins and then flows into the right ventricle through the tricuspid valve.

4. **Conclusion**:
- Therefore, we can conclude that the right atrium of a mammal's heart receives blood from the superior vena cava and the inferior vena cava.

### Final Answer:
The right atrium of the heart of mammals receives blood from the superior vena cava and inferior vena cava.

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