Blood that comes in to the right atrium comes from the pulmonary vein.
blood first enters the heart through the right atrium.
Veins, specifically the vena cava, enters the right atrium of the heart.
Veins return blood to the heart. Four veins enter the heart. The superior vena cava (SVC) returns blood from the head, neck and arms and enters the right atrium of the heart. The inferior vena cava (IVC) returns blood from the rest of the body and also enters the right atrium of the heart. The left and right pulmonary veins return blood from the lungs and enter the left atrium.
Oxygen-poor blood enters the heart through the right atrium
Inferior vena cava
The right atrium is where deoxygenated blood enters the heart.
Right atrium
When blood leaves the lungs through the pulmonary veins, it returns to the heart and enters the left ventricle.
Blood returning from systemic circulation enters the heart at the right atrium. Blood from the pulmonary circulation enters the left atrium.
The blood enters through the superior and inferior vena cava.
The blood re-enters the heart through the superior vena cava and into the right atrium.
blood returning to the heart from the upper portion of the body enters the right atrium through the superior vena cava.