A.1.1 – Balance

Defined Words: semicircular canals, nausea


Your ears are not just for hearing. Deep within each of your ears lie three looping tubes partly filled with fluid. Those tubes are called semicircular canals and they are the sensory organ involved with balance. Your sense of balance adapted as a way to detect the direction of gravity, a clear advantage to quickly understanding your surroundings. Organisms that could detect light could determine up and down using the sun but only during the daytime, gravity never turns off.

The semicircular canal is a hollow chamber with three loops in each of the three dimensions. Within each loop of the chamber is a wiggling lump of tissue that moves with the fluid. Within that lump, small hair-like cells project inward to detect movement of the fluid when the whole cavity moves. The hair cells are connected to a sensory neuron which then transmits signals to the brain to understand the movement.

We detect gravity because of touch neurons that detect the presence of little solid pieces in the canals. The solid pieces will be pulled by gravity to rest at the bottom of the chamber, whichever way that is. Gravity is always pulling in one direction meaning we can always detect which way is down by which touch neurons are being activated.

Gravity isn’t the only force that acts upon an organism, especially since you have muscles to move you around. Contracting muscles cause forces that move the Organism and leaves the fluid behind briefly. Think about quickly moving a cup of water, the cup moves while the water sloshes backward, then forward when the cup stops. The same thing occurs in your semicircular canals every time you move your head. The reason you have three canals in each ear is because we live in a three dimensional universe. More than three canals wouldn’t have given a great advantage to the organism but less than three would be clearly disadvantageous.

An organ adapted to detect a Fundamental Force isn’t uncommon in nature, though the adaptation cannot occur without a mutation first. Migrating birds have the ability to detect electromagnetic waves and can sense the magnetic field produced by the Earth. We do not have this ability because our senses were good enough to keep us alive without it. Birds with this trait were much better suited to make long journeys across hundreds or thousands of miles.

Your balance is a sense that you don’t have the ability to turn off. While you can choose to close your eyes or cover your ears, your brain maintains a constant connection with your sense of balance. You are constantly receiving signals from your semicircular canals and therefore develop an expectation to continue receiving signals. When the fluid in your ears sloshes around a lot, like on a rollercoaster, the very important expectation is not being fulfilled. When your sense of balance is uncertain, you feel nausea. Standing still or lying down helps when you’re feeling nauseous because it allows your sense of balance to recalibrate.

If your sense of balance stays uncertain, the Organism releases stress which can cause vomiting or fainting. Both of these are helpful for the Organism when it receives stress but doesn’t know how to fix the problem.

Vomiting removes the contents of your stomach in an attempt to remove any food that may be causing you issues. Eating is very important, and eating the wrong thing can be very dangerous. When you are not receiving consistent signals from your balance, your body assumes something is wrong and expels possibly harmful food.

Fainting is helpful because gravity will take over and bring your head even with the rest of your body, as you fall to the ground. In a flat position, the blood can reallocate to wherever it’s needed without having to fight gravity.

Your sense of balance is aided by your sense of sight. Seeing the world around you and understanding the direction of gravity on your environment means you can expect gravity to act on you in the same way. Without your sight, you can still maintain balance but it works in a tug-of-war fashion. When you are standing on two feet with eyes closed, your right foot will push off the ground and send you to the left. Your sense of balance will detect a slight leftward movement and signal the motor center to push with the left, sending you back to the right.

You can experiment with a friend to see this tug-of-war first hand. You will need to stand in a doorframe, or some other stationary reference, with your eyes closed. Your friend will then notice you slightly swaying back and forth but you won’t be able to consciously feel those subtle movements!

The doorframe experiment also shows another important feature of your sense of balance: the automated connection to your motor center. The fact that you don’t know you’re moving at all shows that your consciousness is not present in the neural path between your semicircular canals and your muscles. There is a reason athletes often have very good balance: they have a strong understanding of their own body movements combined with an automated link to their semicircular canals.

The more time you spend solidifying your proprioceptors, the better balance you will have. While your balance receptors are located in your head, it’s important to remember that your center of gravity is much lower. Sitting in a chair without using y our core means we compensate with other muscles just to keep our heads up. This causes sedentary posture which causes loads of other health risks!

Take some time to find your body and lower your center of mass to its proper anatomical position. It will take some time, but eventually your sense of balance will expand to more of your body than just the parts you need to work at a desk and walk between different seats.

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