An atrium is a chamber in the heart that receives blood.
The human heart has two atria: the right atrium and the left atrium. The right atrium receives deoxygenated blood from the body via the superior and inferior vena cava. This blood then travels to the right ventricle to be pumped to the lungs for oxygenation.
The left atrium receives oxygenated blood from the lungs via the pulmonary veins. This oxygen-rich blood then flows into the left ventricle, ready for circulation throughout the body.
Think of the atria as entry points for blood returning to the heart, preparing it for its next journey through the circulatory system. Their thin walls allow for easy blood flow into the ventricles. They contract briefly, assisting in filling the ventricles, ensuring sufficient blood volume before the powerful ventricular contractions begin.
