There are four chambers inside our heart. The Right and left Atria (atrium for singular) The Right Atrium collects blue venous deoxygenated blood from our body, then the right ventricle pumps deoxygenated blood out from our heart to the lungs for oxygenation. The left atrium receives red oxygenated blood from our lungs, and the left ventricle pumps oxygenated blood out of our heart to all parts of the body. Hope it helps!
The heart is divided into four chambers. the two upper chambers are called the atria(sing.atrium)the two lower chambers are called the ventricles. the left and right chambers separated by a wall called septum,which prevents the mixing of oxygen-poor  and oxygen-rich blood.