The Right Atrium Receives Blood from the Superior and Inferior Vena Cava

The correct answer is option 'D' which states that the right atrium receives blood from both the superior and inferior vena cava. Let's understand this in detail.

Anatomy of the Right Atrium
The right atrium is one of the four chambers of the heart and is located in the upper right portion of the heart. It receives deoxygenated blood from various parts of the body and pumps it to the right ventricle. The right atrium has several openings through which blood enters.

The Superior Vena Cava
The superior vena cava is a large vein that carries deoxygenated blood from the upper body to the heart. It receives blood from the upper extremities, including the arms, head, and neck. The superior vena cava enters the right atrium from the top, delivering deoxygenated blood to the heart.

The Inferior Vena Cava
The inferior vena cava is another large vein that carries deoxygenated blood from the lower body to the heart. It receives blood from the lower extremities, including the legs, and also from the abdominal organs. The inferior vena cava enters the right atrium from the bottom, delivering deoxygenated blood to the heart.

Function of the Right Atrium
The right atrium acts as a receiving chamber for deoxygenated blood. When the heart muscle relaxes, blood flows passively from the superior and inferior vena cava into the right atrium. During atrial contraction, the blood is then pushed into the right ventricle, which pumps it to the lungs for oxygenation.

Summary
In summary, the right atrium receives deoxygenated blood from both the superior and inferior vena cava. The superior vena cava carries blood from the upper body, while the inferior vena cava carries blood from the lower body. This blood is then pumped to the right ventricle, which sends it to the lungs for oxygenation.