“Chunking” takes on a whole new meaning…or…What REALLY causes motion sickness?

On September 13th I will board the Oceanus, the research vessel of Oregon State University. I feel honored to join this cruise, along with two other teachers and four high school seniors from up and down the Oregon Coast. (One of the students is the son of our own Mr. Wood – how cool!) While on the 3-day cruise, I will try to write daily blogs about the research we are conducting; then on Friday and Saturday of that week we will be helping OSU in Portland with tours of the ship and other educational ventures.

I’ve never spent this long on a ship (well, except for that time on the Alaska ferry a couple years ago) and I’m a little afraid I might get seasick. OK, I’ll be honest – I’m a lot afraid.  Once I did a day trip to see pelagic birds (they live mostly out on or above the open ocean) and I felt horrible the whole time.  Rumor has it (Kraft, 2015) that ⅓ of people on a boat or ship get sick with even just a little motion, but ⅔ of us get sick with heavy motion (whatever THAT means – isn’t it a matter of perspective?). Anyway, just in case I *do* get seasick, I decided to write a blog post about the science of motion sickness. I’m sure I won’t want to write about being seasick while I’m actually seasick (UGH! Imagine describing how you feel when you’re hugging the toilet!), so I’m doing this ahead of time. Even as I write I feel a little nauseous. Hmm.

To start off, I decided to look up slang phrases that describe how I might feel or what I might do if I get seasick. I found these colorful terms or phrases on Urban Dictionary.

The obvious synonyms:

  • Puke
  • Hurl
  • Barf
  • Upchuck

More colorful phrases:

  • Pray to the porcelain god
  • Toss a sidewalk pizza
  • Tango with the toilet
  • Make modern art in the toilet
  • Have a technicolor yawn
  • Revisit your breakfast
  • Vomit your victuals
  • Perform peristaltic pyrotechnics
  • Paint the town red… and green and orange and pink

These are my two favorites (today):

  1. Become a multicolored organic fountain
  2. Drive the porcelain bus

I tried to find a good picture of a real multicolored fountain, but I came across this picture of the fountain at the Seattle Center, and I used to LOVE going to this fountain when I was a kid, so I’m showing it instead of a multicolored fountain. This is because it’s my blog, and even though I’m trying to make it seriously about science, I keep getting distracted by fun stuff.

OK, but let’s get serious.  What actually causes this horrible affliction of Motion Sickness? This need to drive the porcelain bus? I’ve always heard that motion sickness is caused by your inner ears, but since I do teach Anatomy & Physiology, I really should try to understand exactly WHY this happens and WHAT it means.

 ear_anatomy_4*Photo from http://www.carolinaear.com/patient_resources/patient_education.shtml.

The ear is an amazing organ of the Nervous System. It’s pretty complex, so I can see why it would be nervous. Notice the nerves attached to the inner ear: the Vestibular nerve, Facial nerve, and Cochlear nerve (also called the Auditory nerve). The inner ear itself lies within the temporal bone (looks like spongy bone, for any of my A & P students reading this) and consists of the Cochlea and the Semicircular canals.

The brain senses motion from three sources in our bodies: the nerves of the ears, of the eyes, and proprioceptors, which are receptors found in muscles, joints, and their surrounding tissues (Medical Dictionary, 2016). The sensing of motion relies on all three inputs, but to different degrees. For example, if there is no input from the ears, motion sickness will not develop; likewise, visual input appears to be less important for the brain to sense motion than do the other two sources (Kraft, 2015). To send impulses to the brain, neurotransmitters (chemical messengers) are released by neurons (nerve cells); these neurotransmitters move either to an adjacent neuron or muscle cell, depending on the type of neuron and neurotransmitter that are involved in the message.

According to Kraft (2015), three neurotransmitters are involved in the sensing of motion by the brain: histamine, acetylcholine, and norepinephrine. Note that these neurotransmitters have other functions, as well, but that’s a whole ‘nother blog post. I always wondered why people take antihistamines for motion sickness — these drugs prevent the release of the neurotransmitter histamine, so your body does not attack allergens, which is the cause of allergies (yep, another blog post subject). I’d always thought antihistamines were just to treat allergy symptoms, so the practice of taking them for motion sickness didn’t make  sense to me, but now I know why! Pretty cool!

But I digress. The reason I brought up the neurotransmitters was to explain the sensations of motion sickness. These neurotransmitters are released from different types of neurons to tell your brain you are moving. Your brain takes complex information from three different sources and puts it all together to let you know you are, in fact, in motion. When the motion is caused by YOU – you’re swimming, riding your bicycle, or hiking to find a geocache, the brain handles the three conflicting inputs well. The problem arises when your body is not causing the motion: being in a vehicle, for example. When you are in a car, airplane, or on a ship, your brain is not coordinating the movements of your body. This messes with the balance of the neurotransmitters involved in motion. Thus medicines to treat motion sickness usually target the control and balance of the three neurotransmitters.

I think I’ll end this post here, as I really don’t want to discuss the symptoms of motion sickness. Thanks for reading and until next time!


References Cited

Kraft, Sy, 8 September, 2015. “Motion Sickness (Travel Sickness): Causes, Symptoms and Treatments”, Medical News Today. http://www.medicalnewstoday.com/articles/176198.php. Retrieved 27 August, 2016.

Medical Dictionary, 2016. “Proprioceptors Definition”, Medical Dictionary. http://medical-dictionary.thefreedictionary.com/proprioceptors . Retrieved 28 August, 2016.

Urban Dictionary, http://www.urbandictionary.com/define.php?term=vomit. Retrieved 27 August, 2016.

10 thoughts on ““Chunking” takes on a whole new meaning…or…What REALLY causes motion sickness?

  1. Great info! I never understood the science behind motion sickness. Here’s a question for consideration: Is it possible to condition yourself to maximize motion tolerance? We used to live in an area only accessible by miles of windy roads. No one who lived there ever got sick but it was very common for visitors to pull over and hurl. Thoughts?

  2. Great question, Katrina. I’ll have to look into it, but I would guess that you can. I’ve heard stories about sailors getting sick for a day or two, then they’re fine.

  3. Your piece on sea sickness was actually quite interesting! I never thought of vomiting in the way that you stated it. The piece on the brain functions was especially good.

  4. I love hearing about your knowledge of the ear, i did not know that you could get seasick from your ears. I like how you went into detail about the ear, and all the other parts of the ear, such like facial nerve. I also like the the picture/ diagram of the ear because it gives you a good picture of the inside of the ear. I also learned that the ear is a very complex part of the human body, because I did not really know about the ear at all, but now i know much more then i did before.

  5. Dear Mrs. Almasi,
    I found you blog very fantastic and I loved reading and visioning of what you went through. I loved reading about the brain seances motion from three sources from our body.

  6. Wow this was a very interesting blog Ms Almasi.
    The one part i found really cool was how our brain and ears and all of the senses around there can trigger motion, but when your on a boat or what i thought of was a plane, we do not sense any type of motion and it is hard for our brain to accept these changes. One question i have is can our senses ever be disrupted? And what i mean is, can any of our sense like reading a book be interrupted and lost and lead to a loss of memory? Because i had motion sickness and as i look over the water it seems to disappear. Thankyou Ms Almasi for this interesting and fun blog.

    • Hi AJ,
      What an interesting question! Yes – we can disrupt what we are sensing. This could happen in a negative way from a disease or injury, but I think what you are describing is a little different. We can reduce motion sickness in a variety of ways – with medications, herbs, fresh air, and by focusing your vision far away, as you describe. Your eyes are seeing something distant that does not appear to move back and forth, so this is a great way to change the perception that you are moving. I hope that answers your question!

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