Right ventricle: The lower right chamber of the heart that receives deoxygenated blood from the right atrium and pumps it under low pressure into the lungs via the pulmonary artery.

The tricuspid valve is located between the right atrium and right ventricle and ensures the flow of blood from the right atrium into the right ventricle and prevents the reverse.

The pulmonary valve is situated between the right ventricle and the pulmonary artery and performs similarly as a one-way valve.

Right atrium: The right upper chamber of the heart. The right atrium receives deoxygenated blood from the body through the vena cava and pumps it into the right ventricle which then sends it to the lungs to be oxygenated.

Pulmonary artery: One of the two vessels which are formed as terminal branches of the pulmonary trunk and convey unaerated blood to the lungs. The two pulmonary arteries differ in length and anatomy.

The right pulmonary artery is the longer of the two. It passes transversely across the midline in the upper chest and passes below the aortic arch to enter the hilum of the right lung as part of its root.

The left pulmonary artery is the shorter of the two terminal branches of the pulmonary trunk. It pierces the pericardium (the sac around the heart) and enters the hilum of the left lung.

Left ventricle: The left lower chamber of the heart that receives blood from the left atrium and pumps it out under high pressure through the aorta to the body.

Left atrium: The upper right chamber of the heart. The left atrium receives oxygenated blood from the lungs and pumps it down into the left ventricle which delivers it to the body.