The heart is a syncytium. This means that it can conduct an electrical signal throughout its structure using gap junctions, ensuring that the cardiac muscle cells in each chamber wall contract together.

There is a variety of blood vessels associated with the chambers of the heart. These are best understood by studying the route of blood through the cardiovascular system (see also the accompanying diagram).

• Deoxygenated blood enters the right atrium through the inferior vena cava.
• Right atrium to right ventricle.
• lood pumped from the right ventricle into the pulmonary trunk (then x2 pulmonary arteries), then arrives in the lungs. Blood is oxygenated here.
• Pulmonary veins drain blood from the lungs to the left atrium.
• Left atrium to left ventricle.
• Blood pumped from the left ventricle into the aorta, travels around the body and becomes deoxygenated.
• Back to the start.