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10 Facts About the Human Body You Probably Never Knew

6. When you shout, your brain kind of turns down your hearing so you don’t deafen yourself.

Image credits: Pixabay

Whether it is to cheer up for your favorite team or to assert your point during a fight, we have screamed or shouted at least once in our life. But have you ever thought why that doesn’t it make you deaf? Scientists have found out that during such situations there are special brain cells that kick in and save you from going deaf. The moment you start screaming or shouting, these cells dampen the auditory neurons’ ability to detect incoming sounds. The inhibition signal sent by these cells is called “corollary discharge.” The moment you stop shouting, the corollary discharge stops and your normal hearing ability resumes.

In the human body, there exists a second mechanism that protects our hearing. The bones in the middle part of our ears have two tiny muscles attached to them. When exposed to loud noises, these muscles contract making our auditory system less responsive to incoming sounds. This is called the “middle ear reflex.” (source)

7. There exist neurons deep within the human brains that monitor our behavior, catch errors, and correct them quickly. They are known as “error neurons.”

Error neuron
Image credits: Digitalbob8/Flickr

Committing errors is an integral part of our daily life. While some of us keep them in mind and refrain from making the same mistake again, others keep on repeating them. Usually, it is attributed to one’s nature or behavior or the way they were brought up. But recently, scientists have detected some cells deeply embedded in our brain that constantly monitor our behavior. These cells also catch errors and correct them.

A Caltech-led team of researchers has found and identified individual neurons that are the main reason behind our error detection and correction ability. Sometimes we realize we are making mistakes even though we might not be able to see it up front. For example, while typing one can understand that they have typed a wrong key without looking at the screen. This shows that we self-monitor our own mistake. The study by Caltech scientists has proved the presence of neurons dedicated to this specific work. These neurons are called the self-monitoring “error neurons.” Scientists believe that this discovery may have implications for the treatment of psychiatric conditions like obsessive-compulsive disorder and schizophrenia. (1, 2)

8. If you move your eyes too quickly, your brain will freeze details that should be blurred and process that image, preventing you from actually seeing motion blur.

Have you ever checked your eyes while standing in front of a mirror? If not, then try it. You will observe that in reality, you might be moving your eyes, but you can never observe it in a mirror. This is due to the fact that our brain purposefully blocks our vision when our eyes move. This process is known as “saccadic masking.”

Saccadic masking was discovered in 1898 by Erdmann and Dodge. Our brain performs saccadic masking to suppress motion blur. During eye movements, the brain selectively blocks visual processing making us effectively blind for some microseconds. In the absence of saccadic masking, our vision would be blurred frequently and might result in distraction and nausea. (1, 2)

9. The human body becomes approximately one centimeter taller in the morning than later in the day.

Measuring height
Image credits: Woodleywonderworks/Flickr

Believe it or not, you are actually taller in the morning than in the evening. Try measuring yourself in morning and evening, and you will find that you are one cm taller in the morning. The reason behind this change is the gravity compressing cartilage in our spine and in other parts of our bodies.


When we sleep at night, we are lying down in a resting position. During this time, our spine decompresses or “spreads out.” So, when we wake up, we are taller than the time when we went to sleep. As our day progresses, we engage in various activities. While performing these activities, the cartilage of our knees and spine gradually compress. Also, gravity flattens the cartilages between the vertebrae. It also pushes out the water between our spinal discs while we are standing. So, as the day progresses, we gradually become a tiny bit shorter again. (1, 2)

10. There exists a “second brain” in humans located in the gastrointestinal tract and called the “enteric nervous system.” More than 90% of the body’s serotonin lies in the gut as well as about 50% of the body’s dopamine.

Before starting some daring work such as an adventure sport or even an interview, most of us have experienced the feeling of “butterflies” in the stomach. Usually, we dismiss it as a case of nerves. But guess what? Scientists have found that it is indeed a case of nerves, but these nerves are not the ones residing in your brain. Your gut feeling of butterflies actually comes from the nerve endings residing in your stomach. Our gut is lined with a network of neurons that is so extensive that it is often referred to as a “second brain.” Technically known as the “enteric nervous system, ” it is formed of sheaths of neurons. These neurons are embedded in the walls of our alimentary canal which measures about nine meters from esophagus to anus.

Our second brain is a huge network of neurons. It contains about 100 million neurons which are more than in either the spinal cord or the peripheral nervous system. The enteric nervous system controls the gastrointestinal system and monitors the entire digestive tract from the esophagus to the anus. It acts independently but is constantly in touch with our brain and central nervous system. Also, 90% of the serotonin in our body is produced there, and even half of the dopamine produced in our body is located there. (1, 2, 3)


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