by Nicole Gadda
When’s the last time you ate a burger and fries? Picture the way your burger looked–maybe it had a brioche bun, or it was covered with tomato, onion, and lettuce. Can you remember the conversations of the other people at the restaurant around you, or hear the server take another table’s order? Think of the taste and the smell–cheesy, warm, and juicy. Your body’s senses are to thank for the wonderful experience of biting into a perfectly grilled burger!
Eyesight, hearing, taste, touch, and smell are the five basic senses of the body. Throughout our daily lives, our experiences are converted into chemical signals that send information to our brain to help us understand our environment. This occurs through thousands of receptors, which are structures inside or on the surface of cells that can respond to stimuli. For example, we have photoreceptors in our eyes that allow us to see light so we can watch our favorite movies and TV shows. In addition, adults have 2,000 to 4,000 taste buds on the tongue that allow us to taste things that are salty, sweet, sour, bitter, and savory. Mechanoreceptors are responsible for the sensation we feel when we share a hug with a friend, whereas hair cells in the ear are the sensory receptors that allow us to hear our favorite songs! Finally, the olfactory bulb of the nose has receptors that allow us to smell things like freshly bloomed flowers in the spring.
These five basic senses are great for experiencing the world around us, but did you know that humans actually have more than five senses? It’s true–the human sensory system is complicated! Most scientists agree that there are about 10 different senses, although some argue that there are up to 33 senses in total! For example, thermoception helps us sense heat, while nociception helps us sense pain. We also have receptors that can sense itch, pressure, and vibration. Next time you go to a yoga class, you can tell the instructor that the stretch you feel while touching your toes is due to kinaesthetic receptors in our muscles and tendons that help us detect stretching.
We also have a sense called proprioception–which is the sense of where your body is in space. Receptors that sense these feelings are located in the muscles, tendons, joints, and the inner ear, where hair cells can pick up the direction your body is moving in based on fluid that moves around while you’re in motion. You can thank proprioception for being able to walk forward with your eyes closed! On the other hand, this sense is to blame for motion sickness. Nausea or an upset stomach can occur in vehicles because your proprioception receptors sense forward movement as you drive, but your other senses send signals to your brain saying you’re comfortably seated in the passenger seat. These conflicting messages to your brain can result in motion sickness!
Understanding how our senses work can help scientists discover ways to artificially replicate them in people who have lost specific senses. For example, our ears respond to sound waves in the environment, convert them into signals our brain can understand, and send them to the brain to interpret as music or conversation. Researchers who study this process can replicate it through hearing aids that artificially convert sounds into signals for the brain to understand. Technology like this helps people with lost or worsening hearing regain the ability to hear sounds again.
Next time you’re on a walk, going to a concert, or eating at a new restaurant– try seeing how many senses you can identify working at once. Can you think of an activity that will use all 10 senses at the same time?
