Anatomy of the Heart

Summary

The video explains the heart’s structure and how it moves blood through the lungs and the rest of the body.

Chambers, walls, and valves

The heart has four chambers: the right and left atria are the upper chambers, and the right and left ventricles are the lower chambers. They contract in a coordinated rhythm to create the heartbeat.

The interatrial and interventricular septa separate the heart’s left and right sides. The tricuspid valve leads into the right ventricle, and the bicuspid (mitral) valve leads into the left ventricle. Chordae tendineae hold these valves in place as the ventricles contract. The pulmonary and aortic valves control blood leaving the ventricles and help prevent it from flowing backward.

Heart muscle and contraction

The myocardium, or heart muscle, has three layers arranged around the lower part of the heart. Their different directions of movement help squeeze blood through the heart. Pacemaker cells produce electrical signals that cause heart muscle cells, or myocytes, to contract together.

Blood flow

Deoxygenated blood from the body enters the right atrium through the superior and inferior vena cava. It moves into the right ventricle, which pumps it to the lungs to take up oxygen and release carbon dioxide.

Oxygen-rich blood returns from the lungs through the pulmonary veins to the left atrium, then moves into the left ventricle. The left ventricle pumps it through the aorta to the body.

Blood supply and typical activity

The first branches of the aorta are the coronary arteries, which supply the heart muscle with oxygen and nutrients. Other branches carry blood to the head, arms, and the rest of the body.

The heart typically beats about 60–100 times per minute and pumps roughly five quarts of blood through the arteries in one minute.

Speakers and sources

• Narrator: An unnamed voice-over narrator; no individual speaker is identified in the subtitles.
• Video source: Nucleus Medical Media, as identified in the video metadata.