Identify the structure of the human heart which is a valve that closes during each heartbeat to prevent blood from flowing back into the right ventricle from the pulmonary trunk.

The answer is pulmonary

valve. The pulmonary valve is found between the right ventricle and the pulmonary artery. The valve is a semi-lunar valve that opens when the pressure in the right ventricle is higher than that in the pulmonary artery (because the ventricle is filled with blood). When the ventricle pumps blood into the pulmonary artery, the pressure in the artery rises while that in the ventricle lowers. This closes the pulmonary valve preventing the backflow of blood into the right ventricle. Pulmonary artery takes blood to the lungs for oxygenation.