Right Atrium - Location, Anatomy & Function - Human Anatomy | Kenhub
Left Atrium Heart Chamber Anatomy - Human Anatomy | Kenhub
Right atrium and ventricle overview (preview) - Human Anatomy | Kenhub
Left atrium and ventricle (preview) - Human Anatomy | Kenhub
The atrium is the upper chamber in which blood enters the heart. There are two atria in the human heart, which receive blood – the left atrium from the lungs, and the right atrium from the venous circulation. The atria receive blood, and when the heart muscle contracts, pump blood to the ventricles. All animals with a closed circulatory system include at least one atrium / auricle.