The Ear
Episode 12
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Czech Title Ucho
Original (French) Title L'Oreille
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The Eye The Skin
The Ear is the twelfth episode of Once Upon a Time... Life. Its plot focuses on how we hear and how our ears help us keep our balance.

Plot Edit

The episode begins as a young Claire plays the piano. Peter, sitting on stairs in front of the door, hears the music and then narrator explains how are the sound waves registered to nerve impulses. The scene zooms in Peter's ear canal, reaching the vibrating eardrum and auditory ossicles. The vibrations are passed onto the cochlea and to organ of Corti. In the mentioned area, Sodium Ions swim freely in cochlea and in between the cells of Corti organ.

In one of the cells, the chiefs register medium vibrations coming from Claire's piano. The main chief requests for Sodium Ions to enter the cell and transmit the signals. One of the workers asks his colleague why can't he hear anything when their job is to transmit the vibrations; not convert them into sound. Once inside the nerve fiber, the Ions, in union, transmit the Neurotransmitters that take appearance on musical notes. Inside of the nucleus of a nearby neuron, a common Neurotransmitter receives the message regarding vibration and, with others, transmits it down the axon. The impulse reaches the nucleus and give the messages to sound chiefs. This process repeats until the impulse reaches the temporal lobe where the vibrations become sound.

Claire begins to play another music piece on her piano and Peter snaps his fingers to gain the rhythm. Inside the nucleus, Maestro, his assistants and some Neurotransmitters gain rhythm as well. In the bloodstream, the Red Corpuscles feel the eardrum vibrations and they, along with other blood components, begin dancing. After a while, Claire goes back to playing the song she was at the beginning of episode. In one of the blood vessels in the tissue of eardrum, the blood residents feel strong shakes. Lieutenant Claire feels that there's something wrong in the area and guides Peter out of the blood vessel. Globus explains to Globin and Hemo where do these vibrations come from. The scene switches to the air space in middle ear.

In the middle ear, a group of Bacteria with flashlights climbs up the Eustachian tube, planning on causing otitis. However, they notice Peter and Claire in Lymphocyte vehicles and duck. They're caught and the Antibodies arrive to neutralize the germs identified as Staphylococci. In the outside world, Peter blows his nose and then goes cycling with Claire.

The traffic is dense and there is a lot of noise registered by Peter's cochlea. The chiefs recognize it as 140 dB, which is becoming rather painful and pain messengers are sent. Peter and Claire cover their ears. In the nucleus, the young chief is overwhelmed with messages he has to proceed and realizes it's pain messages. Then, a short montage of how humans were able to hear much more accurately is shown, cutting to a scene with very loud vibrations, causing Corti organs' cilia to shatter. Doctor Maestro, diagnosing a boy, tells his mother that he should be careful in the future as loud noise causes stress and unrepairable damage.

The rest of the episode focuses on how we maintain our balance through ears. Peter and Claire go slowly and try to keep their balance, but find it difficult. The scene zooms in on the blood vessels around semicircular canals. Globus explains how, when head moves, the liquid inside the vestibular system shakes, sending signals regarding how our balance is affected. The Sodium Ions transmit messages that head is tilted forward. The signals reach the cerebellum where balance is maintained. The chiefs discuss with the main Chief what should be done. As they go back to their seats, the narrator ends the episode:

"The ear is the organ of hearing, but as we've just seen, that's not all. With the vestibular apparatus and the semicircular canals, the ear is also the organ of balance. Without our ears we could never stand up, let alone ride a bike!"

Trivia Edit

  • This episode features two new types of Neurotransmitters:
    • Sound Neurotransmitters, which take appearance on blue and red musical notes.
    • Balance Signals, which take appearance on babushka dolls.
  • The second episode to revolve around senses.
  • This episode features Sodium Ion characters that are very similar to Electrons.

Biology Edit

Sense of hearing and balance Edit


Structure of the human ear.

  • Located in the ear, with a purpose to receive the sound vibrations from the outside world, and transmit them further into the central nervous system where they'll be converted into the sound.
  • The ear consists of three regions:

Outer ear — the outermost region that has the direct contact to the outside world. Consists of following parts: Edit

  • Pinna — a cartilaginous formation shaped oval and the visible part of the outer ear. Its purpose is to catch the vibrations to be transmitted further down.
  • Ear canal — a tube that spreads the vibrations from pinna to the eardrum.
  • Eardrum — a sensitive, drum-like skin membrane that sends the vibrations to the ossicles.

Middle ear — the middle region that is full of air and connected to pharynx. Consists of three sound bones, called ossicles, and a canal: Edit

  • Hammer (malleus) — the first bone.
  • Anvil (incus) — the second bone.
  • Stirrup (stapes) — the third bone and the smallest bone in the human body. Passes the vibrations to the inner ear.
  • Eustachian tube — a tube that links the middle ear to pharynx.

Inner ear — it's filled with lymph with following organs: Edit

  • Cochlea — a spiral-shaped cavity that contains Corti organs which register the sound waves.
  • Semicircular canals — three canals that contain balance receptors.
  • Auditory nerve — a sensitive nerve that transmits the sound waves to the temporal lobe of the brain.

Taking care of our ears Edit

  • Decibel levels

    Sound limits.

    Our hearing ability concerns three elements to be healthy:
    1. The ear
    2. The auditory nerve
    3. The auditory center
  • Our balance ability concerns three elements to be healthy:
    1. The ear
    2. The sensitive nerves
    3. The cerebellum
  • In a sound wave, we differ its strength (calculated in decibels (dB)) and its frequency (calculated in Hertz (Hz)).