The right ventricle pumps blood to the lungs where gas exchange takes place.

The idea

Deoxygenated blood returns from the body through the vena cava into the right atrium. The right atrium contracts, pushing blood through the tricuspid valve into the right ventricle. When the right ventricle contracts, blood leaves through the pulmonary artery to the lungs. In the lungs, oxygen diffuses from the alveoli into the blood, and carbon dioxide diffuses from the blood into the alveoli to be exhaled. The right ventricle has a thinner muscular wall than the left because the lungs are close and the required pressure is lower.

What earns the marks

• States that the right ventricle receives deoxygenated blood from the right atrium.
• Describes the right ventricle contracting to pump blood through the pulmonary artery to the lungs.
• Identifies the lungs as the site of gas exchange where oxygen enters and carbon dioxide leaves the blood.
• Links the thinner wall of the right ventricle to the lower pressure needed to reach the lungs.
• Explains that oxygen and carbon dioxide diffuse between alveoli and blood down concentration gradients.

Common mistakes and how to put them right

• Saying the right ventricle pumps oxygenated blood.

  Put it right by stating it pumps deoxygenated blood to the lungs.

• Confusing the pulmonary artery with the aorta.

  Put it right by stating the pulmonary artery carries blood to the lungs.

• Stating that gas exchange occurs in the bronchi.

  Put it right by identifying the alveoli as the exchange surface.

Exam tips

• Use the terms deoxygenated and oxygenated accurately when describing blood flow.
• Link the thickness of the ventricle wall to the distance and pressure required.
• Practise tracing blood from the vena cava to the lungs and back to the heart.