jBrAD’s Things You (maybe) Didn’t Know: Making Senses

We're all familiar with the traditional "five senses" (sight, hearing, touch, smell, and taste) celebrated in song and story.

The notion of five senses is credited to Aristotle, who also believed that everything in the universe was made out of earth, air, fire, water, and aether. So that tells you how seriously you have to take HIM. It turns out, in fact, that there are at least nine senses, and most researchers think there are up to twenty-one.

Ready for a tour through the New Sensory Carnival? Keep reading.


Sight.  This is, technically, two senses: one for colour (cones) and one for brightness (rods). (The ability of some women to see shoe stores at 1000m or men to see sales on pressure washers on sale from kilometers away is thought to be an autonomic function).

Taste. And this one, too, is more complicated than you'd think. Taste is actually FIVE senses by itself due to the differing types of taste receptors: sweet, salty, sour, bitter, and umami (detects the amino acid glutamate - mostly found in meats and MSG). The taste sense, unlike sight, is based on a chemical reaction. (Remember, the little black dress is always tasteful and never goes out of style).

Touch: Yeah, we know it's already an Aristotelian "sense": but "touch" has been found to be distinct from pressure, temperature, pain, and even itch sensors - and entirely different from the "punch in the shoulder joint" sensor (as administered by my brother). Touch, broken down, includes complete separate "senses" like:

• Pressure (in the tactile sense)
• Itching:  Surprisingly, a distinct sensor system from other touch-related senses (my cup runneth over).
• Thermoception: 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 of a completely different type of thermoceptor in the brain, used for monitoring internal body temperature (observe the senior citizen who can NEVER get a cup of coffee that is hot enough to suit them!)

Sound: detecting vibrations along some medium (air or water, etc) that is in contact with our ear drums.

Smell: another that is a product of a chemical reaction. This sense combines with taste to produce flavours (except the smell of Thurso, Quebec, which produces Pulp and Paper).

Proprioception: this sense gives you the ability to tell where your body parts are, relative to other body parts. The famous drunk driving test "close your eyes and touch your nose" is testing this sense. It is used all the time in little ways, such as scratching an itch on your foot without looking at it. (Good thing, too. I'd hate to think of where my body parts would end up if I didn't have a system to keep track of them).

Tension Sensors: These are found in such places as your muscles and allow the brain the ability to monitor muscle tension.

Nociception: in a word, pain, once thought to be the result of overloading other senses, such as "touch", but has been found not to be the case. 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). Aren't you glad that you can hurt in more ways than you can smell? You're not? Ok, moving right along...

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. This one lives in your inner ears,  and, when described by guys in white lab coats, is called the vestibular labyrinth system. Anyone who's ever had this sense go out on them on occasion knows how important this is. When it's not working, you can't tell up from down and moving from one location to another is extremely difficult. Terry reports that a sudden loss of up/down-ness is common among divers because of sudden flooding in the ear.

Stretch Receptors: These are found in places such 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. You know that feeling when you wake up in the night and you have to...well, anyway, that's the stretch receptors at work. 

Chemoreceptors: These trigger an area of the medulla in the brain that is involved in detecting blood born hormones and drugs. It is also involved in the vomiting reflex. Have you noticed that the new senses get progressively less fun?

Thirst: You know this one. It's the sense that allows your body to monitor its hydration level and tells you to drink.

Hunger: this system allows your body to detect when you need to eat something. (I've got an extra one if anybody's running short, anyone? anyone?)

 Time: Okay, this one is highly debatable, since no singular mechanism has found that allows people to perceive time (I have cats, works fine). However, experimental data has conclusively shown that humans have a startlingly accurate sense of time, particularly when young. 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. Why some people lack this completely remains a mystery.  

Magnetoception: This refers to either a gathering held to honour the Protector of Mutants, OR the ability to detect magnetic fields, which is principally useful in providing a sense of direction when detecting the Earth's --- ummm.....magnetic field. Unlike most birds, humans do not have strong magnetoception. However, we do have some;  the theory is that this has something to do with deposits of iron in our noses. This would make sense, in that humans who are given magnetic implants have been shown to have a much stronger magnetoception than humans without. (Magnetic Implants? Cool, you could stick a few fridge magnets to yourself and be your own bulletin board).


And there you go. That's our five sense worth. 








Source: http://www.misconceptionjunction.com/