The semilunar valves (the aortic valve and the pulmonary valve) then open and blood is forced out of the ventricles.

Deoxygenated blood in the right ventricle is carried to the lungs through the pulmonary artery. Oxygenated blood in the left ventricle is pumped into the aorta and distributed to the rest of the body.

Once the ventricles have emptied the myocardium relaxes. The semilunar valves then close to prevent blood flowing back into the heart from the arteries.