The Atria Are the Heart's Entryways for Blood The left atrium and right atrium are the two upper chambers of the heart. The left atrium receives oxygenated blood from the lungs. The right atrium receives deoxygenated blood returning from other parts of the body.
Two examples of how the biosphere supports life is by reducing the amount of harmful radiation to reach the surface of the earth. It also gives oxygen for animals to breathe
