Atrium

Definition

A chamber of the heart that receives blood returning to the heart from the body or lungs. Vertebrates have two atria, one receiving oxygenated blood and the other deoxygenated blood.

5 Must Know Facts For Your Next Test

1. The right atrium receives deoxygenated blood from the body via the vena cava.
2. The left atrium receives oxygenated blood from the lungs via the pulmonary veins.
3. Atria are separated from the ventricles by valves that prevent backflow of blood.
4. During a heartbeat, atria contract first to push blood into ventricles before ventricular contraction.
5. In fish, there is only one atrium, while other vertebrates have two.

Review Questions

• What is the primary function of the right atrium?
• How does blood flow between the atria and ventricles?
• How do fish hearts differ from mammalian hearts in terms of atria?

Related terms

Ventricle: one of two large chambers in the heart that pump blood out to the lungs or body

Pulmonary Vein: a vessel that carries oxygenated blood from the lungs to the left atrium

Vena Cava: a large vein carrying deoxygenated blood into the right atrium