What does the right atrium NOT receive blood from?

The right atrium is a crucial component of the heart that collects deoxygenated blood from the body before it is sent to the lungs for oxygenation. Specifically, the right atrium receives blood through two primary vessels: the superior vena cava and the inferior vena cava. The superior vena cava brings blood from the upper part of the body, while the inferior vena cava carries blood from the lower body.

The pulmonary veins, on the other hand, carry oxygenated blood from the lungs to the left atrium, not the right atrium. Therefore, while the superior and inferior vena cavae are responsible for supplying blood to the right atrium, the pulmonary trunk, which branches out to the pulmonary arteries, is involved in transporting deoxygenated blood away from the right ventricle to the lungs. This distinction confirms that the right atrium does not receive blood from the pulmonary trunk.

Understanding this flow of blood is essential for grasping how the heart functions and how it separates oxygenated from deoxygenated blood within its chambers.