Common senses - there are many more than five
WE’RE all aware of the ‘five senses’, touch, smell, sight, hearing, and taste.
But, a bit like certain rock bands who have a bass guitarist that everyone forgets about, the human body possesses a great many more senses that most people have never heard of.
This week, I thought I shed some light on on senses that don’t ever get in the headlines.
Thermoception: The ability to sense heat and cold.
This also is thought of as more than one sense, not just because of the two hot/cold receptors, but also because there is a completely different type of thermoceptor - in terms of the mechanism for detection - in the brain.
These thermoceptors in the brain are used for monitoring internal body temperature.
Proprioception: This sense gives you the ability to tell where your body parts are, relative to other body parts.
This sense is one of the things police officers in the United States test when they pull over someone who they think is driving drunk (you’ll likely have seen a demonstration of this in the show ‘Cops’.
The “close your eyes and touch your nose” test is testing this sense.
This sense is used all the time in little ways, such as when you scratch an itch on your foot, but never once look at your foot to see where your hand is relative to your foot.
It’s also one of the main senses that gets thrown off by experiences like VR games, where your sense of your body doesn’t match your sight. Nociception: In a word - pain. This was once thought to simply be the result of overloading other senses, such as “touch”, but this has been found not to be the case and instead, it is its own unique sensory system.
There are three distinct types of pain receptors: cutaneous (skin), somatic (bones and joints), and visceral (body organs).
Equilibrioception: The sense that allows you to keep your balance and sense body movement in terms of acceleration and directional changes.
This sense also allows for perceiving gravity.
The sensory system for this is found in your inner ears and is called the vestibular labyrinthine system.
Anyone who’s ever had this sense warped due to dizziness or an ear infection knows how important this is.
When it’s not working or malfunctioning, you literally can’t tell up from down and moving from one location to another without aid is nearly impossible.
Stretch Receptors: These are found in such places as the lungs, bladder, stomach, and the gastrointestinal tract.
A type of stretch receptor, that senses dilation of blood vessels, is also often involved in headaches.
Chemoreceptors: These trigger an area of the medulla in the brain that is involved in detecting blood-borne hormones and drugs.
It also is involved in the vomiting reflex and plays an important role in chemotherapy.
Thirst: This system more or less allows your body to monitor its hydration level and so your body knows when it should tell you to drink.
Hunger: This system allows your body to detect when you need to eat something.
Magnetoception: This is the ability to detect magnetic fields, which is principally useful in providing a sense of direction when detecting the Earth’s magnetic field.
Unlike most birds, humans do not have a strong magentoception, however, experiments have demonstrated that we do tend to have some sense of magnetic fields.
The mechanism for this is not completely understood; it is theorized that this has something to do with deposits of ferric iron in our noses.
This would make sense if that is correct as humans who are given magnetic implants have been shown to have a much stronger magnetoception than humans without such implants.
Time: This one is debated as no singular mechanism has been found that allows people to perceive time.
However, experimental data has conclusively shown humans have a startling accurate sense of time, particularly when younger.
The mechanism we use for this seems to be a distributed system involving the cerebral cortex, cerebellum, and basal ganglia.
Long term time keeping seems to be monitored by the suprachiasmatic nuclei ( responsible for the circadian rhythm).
Short term time keeping is handled by other cell systems.