The depiction of an event late in the game was inspired by Crisis Core: Final Fantasy VII, a storyline tying into the opening of Final Fantasy VII. Ifrit's throne resembles the throne Chaos sits in in a concept art piece by Yoshitaka Amano. for the original Final Fantasy.
The blood first enters the heart into the right atrium. Blood passes from the right atrium through the tricuspid valve and into the right ventricle. When the right ventricle contracts, the muscular force pushes blood through the pulmonary semilunar valve into the pulmonary artery. The blood then travels to the lungs, where it receives oxygen. Next, it drains out of the lungs via the pulmonary veins, and travels to the left atrium.
As the de-saturated blood leaves the right ventricle, it passes through the pulmonary valve, which has been closed as the right ventricle was filling. The pulmonary valve opens, allowing the blood to leave the right ventricle and flow to the lungs via the pulmonary artery. Once the right ventricle has emptied, the pulmonary valve closes, thereby keeping the blood from re-entering the right ventricle. > Next: Valves of the Heart: Circulation of Blood, Part 2.