The action of the Heart is that of a double action pump that pumps simultaneously. Blood enters the heart through the superior and inferior vena cava where it then enters the right atrium . Blood then passes through the tricuspid valve into the right ventricle. Finally it enters into the pulmonary arteries for distribution to the lungs.
Now that the blood is in the lungs the CO2 is removed and O2 is replenished into the blood. The blood will now re-enter the heart via the left atrium, then pass through the bicuspid (mitral) valve before going into the left ventricle and being forced into the aorta and out of the heart.
The Heart’s wall is made up of three layers, the outer lay is the Pericardium. The Pericardium is a double-layered membrane that encases the heart like a sac. The outer layer of the Pericardium surrounds the roots of the heart’s major blood vessels and attaches to the Spinal Column, Diaphragm and other parts of the body using ligaments. The inner layer of the Pericardium is attached to the Heart, the main role of the Pericardium is to hold the Heart in position.
The middle layer is the Myocardium, this makes up most of the bulk of the Heart tissue and is responsible for the pumping action.
The final layer is the Endocardium, this is a smooth layer of connective tissue that forms a smooth lining for all four chambers of the heart.