atrium

(noun)

An upper chamber of the heart that receives blood from the veins and forces it into a ventricle. In higher vertebrates, the right atrium receives blood from the superior vena cava and inferior vena cava, and the left atrium receives blood from the left and right pulmonary veins.

Related Terms

Examples of atrium in the following topics:

  • Electric Activity in the Heart

    • The heart is divided into four main chambers: the two upper chambers are called the left and right atria (singular atrium) and two lower chambers are called the right and left ventricles.
    • Physicians commonly refer to the right atrium and right ventricle together as the right heart and to the left atrium and left ventricle as the left heart.
    • The sinoatrial node (also commonly spelled sinuatrial node) is the impulse-generating (pacemaker) tissue located in the right atrium of the heart: i.e., generator of normal sinus rhythm.
    • It is a group of cells positioned on the wall of the right atrium.
    • It is a group of cells positioned on the wall of the right atrium.

  • Pumps and the Heart

    • The septum divides the left and right side of the heart, while the valves of the heart ensure that blood only flows in one direction.They include the tricuspid valve-found between the right atrium and the right ventricle-and the mitral valve-found between the left atrium and the left ventricle.