|Original (French) Title||Le Cœur|
|The Tiny Platelets||Breathing|
The episode begins as the narrator tells a short history documentary of how it was difficult to exclaim the opinions and properties of circulatory system in modern history. Due to this in 1543, Andreas Vesalius, was condemned to be burnt at the stake, but was saved by Philip II of Spain. Michael Servetus, a Spanish doctor who dared to speak of the circulatory system, got executed at the stake ten years later. In 1628, William Harvey, held a presentation regarding cardiovascular system but was ridiculed. Fifty years later, the Dean of the Paris School of Medicine states that there can be no circulation of the blood.
And yet... there is a circulatory system! Driven by the heart.
The scene switches to Red Corpuscles carrying carbon dioxide. Globus tells his fellow blood cells what is about to come as they make their way through vena cava. As usual, Hemo complains about carbon dioxide. Red Corpuscles reach the end of vena cava and shut their gas pouches, which goes more or less good for the exhausted cells.
Red Corpuscles slide down and Globus tells them they have reached the right atrium of the heart where they meet with blood coming from the other parts of the body. As they walk through, they hear a loud bursting noise, which is revealed to be the tricuspid valve while it was in process of closing. The group stays together on a cardiac tissue cliff as the valve opens and the blood residents are swept away. In a huge wind, they pass through the valve and enter the right ventricle.
The Red Corpuscles, startled by strong contractions, prepare to pass through the semilunar valve leading to pulmonary artery. Another group of blood cells arrives to the right ventricle as Globus and the others are strongly ejected into the pulmonary artery. Once there, Globus introduces the concept of pulmonary circulation to Globin and Hemo. On their way, after two Red Corpuscles see Globin putting one of her carbon dioxide molecules on Hemo, they decide to do the same, but he interprets them. On their way to capillaries, Red Corpuscles witness as two Bacterium cells that were feeding on nutrients of the blood are neutralized by the Antibodies.
As they head further, hey found a little hill of cholesterol that is slowly clogging the artery. Globus, Hemo, Globin and a few Red Corpuscles and nutrients climb onto the hill and the former tells them a story of how the similar thing happened in one of his former lives in an unhealthy body. He and his fellow Corpuscles had to squeeze through the blood vessel that was almost fully clogged. The scene zooms out to show Doctor Maestro examining Stroppy with a stetoscope. He describes that he feels pain in chest and left arm, which implies to a slowly developing coronary thrombosis. Stroppy thinks the situation is far less serious, but doctor recommends him to instantly decrease the amount of fatty foods and tobacco.
Stroppy, doing quite the opposite of what the doctor told him, ends up having a heart attack that he survives. Globus, in present, explains that, when the blood vessels get completely blocked, the blood is unable to make its way and deliver the oxygen. After the story, the blood continues to the alveoli, where they finally get relieved for dropping carbon dioxide and loading with oxygen. They slowly make their way into the pulmonary vein.
Suddenly, all Red Corpuscles begin running, speeding up the circulation. This is because Peter, in whose body was the whole episode happening, is running with Jumbo. The two boys stop and rest, exhausted, with same happening to Globus and Hemo. As the circulation goes back to normal, Red Corpuscles reach the end of the pulmonary vein and into the left atrium. The mitral valve opens and they enter the left ventricle. Soon, with startling contractions, Red Corpuscles are swept away through the semilunar valve into the aorta.
Globus reveals that the frightening experience in left ventricle comes from the fact that it's seven times more powerful than the right ventricle, which astonishes the Red Corpuscles. They reach the aorta arch, from where they head into the subclavian artery to arms. Globin asks if the heart rests at all, but Globus denies it and says that heart is simply a fascinating organ.
The episode ends as the narrator lists some heart stats and gives it the title of a fascinating organ.
- The first episode to feature details from history.
- The second episode not to feature Maestro inside of nucleus.
- Heart is a hollow, muscular organ in body of animals, with basic role of circulating blood through the body. It's located in chest area and is protected by the ribcage, which gives it good protection and secures a lot of nutrients and oxygen.
- Human heart weighs roughly between 200 g and 425 g.
- Human heart is divided in two sides: left and right (separated by the muscular wall called septum), which are unevenly divided in atriums (smaller) and ventricles (larger) (separated by heart valves).
- Function of heart valves is to secure that blood can only flow from atrium to ventricle, meaning that their basic role is to prevent blood from going backwards.
- The human heart, in total, has four cavities: right and left atrium, and right and left ventricle. Right side of the heart contains blood full of carbon dioxide and sends it to the lungs in pulmonary cycle. Left side of the heart contains blood full of oxygen and spreads it over body.
- Heart has an electrical conduction system which causes contraction of the cardiac muscle through electric shocks regulated in medulla oblongata. It has two nodes: sinoatrial node and atrioventricular node.
- At the very beginning of aorta, arteries branch in small vessels with the goal to nourish the cardiac tissue; this unique circulatory complex presents coronary circulation.