|Original (French) Title||Le Cerveau|
The episode begins with a historical documentary that shows the development of human brain, after the narrator presenting it as the most fascinating organ in the universe. It slowly shows the montage from archicortex (first developed in reptiles), over paleocortex (in mammals), and finally to neocortex (developed in Homo sapiens). Then, the montage shows how the humans used their advanced intelligence to think, construct, attract and take actions. At the end of the documentary, the narrator shows how sometimes, when reacting to provocations, we are shown to expose some of the primitive sides of our brain (the scene showed Stroppy and Nabot in the traffic as the former gets enraged by the sudden stop of a man in front of him, but calms down when he sees the policeman).
Red Corpuscles, carrying oxygen, set off on their way through one of carotids. Globus tells them that their current goal is to reach the brain; the excited cells prepare for the thrilling experience. During the walk, one of Red Corpuscles tries to flirt with Globin, but is scared away by Hemo. All of a sudden, the system sends the following message:
"Calling all organs of blood population! Accelerate the blood circulation immediately! I repeat: accelerate the blood circulation immediately! Please respond to an urgent request from the heart!"Most of the corpuscles begin to run, but Globus still walks normally, which confuses Hemo and Globin. He explains to them that they are independent and that they don't have anything to do what concerns with the body except the brain, that has the absolute priority. They watch as a policeman dismisses a mineral, a Salt Molecule and a Fat Molecule, who are shocked to this demand. Globus explains that they have to go the other way around because, out of all nutrients and molecules, brain needs oxygen and sugar the most. After walking further into the cortex, Globin wonders if they'll get to reach the neurons to exchange the gases. However, Globus renders this impossible; neurons are far too sensitive to ever come into contact with a blood vessel. A bit later on, the corpuscles watch in amazement as the oxygen bubbles ascend from their baskets and get replaced with carbon dioxide. The scene zooms out from the artery, out of the brain and then finally to reveal that the several next scenes will take place in Jumbo's body as he is running with friends.
Peter, Claire and Peter's Sister are several steps ahead of Jumbo, who is becoming exhausted. He decides to stop, sweating and breathing heavily, while the scene zooms in a nerve cell in tissue of his mouth. There, in the beginning of a dendrite, a Neurotransmitter begins carrying a message and reaches the nucleus. The Chief rearranges the message and sends it further down the axon with several messengers exchanging it along the way. The last messenger arrives to the end of the axon, splitting in nerve endings and handing its message to one among many messengers who cross the synapsis and sprint to the brain.
The chemical messengers pass the messages to be processed. The nuclear enzymes register that Jumbo is thirsty and that it's really hot outside. Them three gleefully give their recommendations: either to ask heart to beat faster, raise the temperature, or inform respiratory and cardiovascular system. The Chief, however, silences them when he asks them to stop showing off, as their job is to pass the messages to medulla oblongata. They do as he requests and signals reach the destination.
In medulla oblongata, a worker asks one of the chiefs what should he do after he receives the information. He recommends contacting the hypothalamus in order to drink something, but another chief dismisses this idea. Another two chiefs inform them that they requested for a rise in the temperature and the acceleration of respiration and heartbeat. They begin to argue about the decisions, but then one recommends that they should transmit the recommendations to the cerebrum so it can decide what option is the best.
Deep in the brain, the astonished Red Corpuscles behold the extremely fast Neurotransmitters. Globus tells them that each order is based on previous knowledge, knowing etc. Globin asks him to explain more and he agrees:
"Well, the brain receives information from all the senses, all the organs as well. It then distributes the information along its neurons, or nerve cells, if you prefer. It's thought of to happen more or less as follow..."In the outside world, Peter slowly leaves the group to buy a rose. He gives the rose to Claire, who takes it. However, due to holding it incorrectly, she pricks her finger; this causes a reaction in which a messenger, transmitting pain, rushes from the nerve ending to the central nervous system. The messengers reach the nucleus and give the different information: regarding that a thorn pricks, that it hurts and that it draws blood. The Chief orders the protein synthesis to store the information. The proteins receive different posters based on the information. The police guides them to where the information is stored (different places for pain, sharp things, warmth, color etc.).
Globin thinks that this whole process sounds simple, but Globus denies it; when an impulse begins, it's lots of messengers, each one carrying a different message regarding the information from the outside world. As Claire stops bleeding, she caresses the rose and another reaction begins in the nasal cavity as the messengers transmit new information; the good smell of the rose, softness of the rose, beauty of the rose, its small weight, its fragility, and its many colors. One of the corpuscles is confused to how can brain store so many information. Globus then explains that, for example, when our eye perceives danger or receives information, the impulses reach the brain that relies on the stored knowledge. In this process, Claire is able not to get pricked again.
As the teens run, Jumbo gets distracted by Stroppy and Nabot smoking. Due to this, he fails to notice the root of a tree he starts tripping on. The nervous system has to work fast to avoid falling. Chief's assistant thinks it's enough to rely on reflex from the spinal cord, but sends the information to cerebellum. The plan on keeping the balance begins:
"This is the cerebellum control room. There's a risk of loss of balance! Automatic regulation through reflex action. Activate automatic regulation. Inform the cortex to take emergency measures."
"This is the cortex control room. Order left leg to move forward quickly to help regain balance. Instruct the hypothalamus to order the adrenal glands to pump adrenaline. As a precaution, bring the arms forward in order to absorb the shock if he should fall."The reflex is carried out and Jumbo regains balance. Globus says that the brain normally stores only what we are consciously aware of due to receiving a lot of information at the same time. When he is asked if the brain has the total control, he replies that the communications between the parts of the brain are unstable as the primitive parts try to dominate; this is shown when Jumbo gets enraged a bit how Stroppy and Nabot puffed smoke at him, but calms down and keeps on running.
- This episode showed the largest scene referring to the human evolution.
- While this episode dealt with the processes going on in the brain itself, the next episode, The Neurones, rather dealt with the processes in nervous system where brain holds no significant role.
- This is the first and only episode to feature different Neurotransmitters from their usual appearance.
- Similarly to the way the vital process was carried out in The Heart, the information transmission was shown slower than the actual properties of nerve impulse.
- The brain is the main part of central nervous system in the humans. Compared to other mammals, humans have much more advanced brains with superior abilities to think, communicate, process and much more.
- Brain is located in head and is protected by cranium, under which there are three protective layers, called meninges that protect both the brain and spinal cord:
- Dura mater — the most solid layer.
- Arachnoid mater — the second most solid layer, similar to spider's web in appearance, hence earning its name.
- Pia mater — the softest layer. The brain and the spinal cord are located directly underneath.
- Between meninges circulates the cerebrospinal fluid.
- The brain consists of following components:
- Brain stem — continuation of the spinal cord that is divided in following parts:
- Medulla oblongata — part of the brain that controls many vital and reflex actions, such as heartbeat, respiration, coughing, swallowing, vomiting etc.
- Pons (latin for bridge) — connects the medulla to midbrain.
- Midbrain or mesencephalon — part of the brain just above the pons. Controls muscle tone and holds the primary centers of sight and hearing.
- Diencephalon — part of the brain located above the brain stem. Its most important parts are:
- Pituitary gland — the main endocrine gland that controls the balance of endocrine system.
- Hypothalamus — located below the diencephalon's core, the thalamus. Regulates body's temperature, hunger, thirst, sleep and emotions.
- Forebrain or cerebrum — the largest part of the brain, divided in two hemispheres. Its properties and advantages are:
- Location of all important actions and senses.
- The left hemisphere controls the right side of the body and is the most active when it comes to physical work, serious business, science and similar topics.
- The right hemisphere controls the left side of the body and is the most active when it comes to creativity, art, music, abstract business and other similar topics.
- Cerebellum — located under the occipitial lobe of cerebrum and is divided in two hemispheres as well. Important for keeping physical balance and motoric functions.
- Brain stem — continuation of the spinal cord that is divided in following parts:
- It's speculated that there are nearly 100 billion neurons in the brain.
- Brain of an adult weighs about 1.3 kg. The size and mass don't have anything to do with intellectual ability, however.