Hundreds and Thousands – The World of Human Senses

The human body and, in fact, all living creatures are amazing.  The intricacies and details that go into putting a person together just make your head hurt.  Take our senses, for example.  Some protect us like some secret alarm system.  Others allow us to feel sensations – touch, smell, sight, sound, taste. 

Here are three groups of senses that just blow my mind when you think about them.

#1 You Have Over Four Million Touch Receptors

You probably do not realise it, because we all take it for granted, but your skin is covered in tiny receptors. These sensors have unique names. Their main job is to detect pressure, motion, and vibrations. Each sends messages to the brain that then cause a reaction.

Humans have billions of individual sensory receptors distributed throughout the body. They can be grouped into about 18 to 20 types of receptor cells. This is based on how they react to different stimuli.

The seven main types of sensory receptors are:

• Mechanoreceptors

• Thermoreceptors

• Nociceptors

• Chemoreceptors

• Photoreceptors

• Osmoreceptors

• Proprioceptors

Touch receptors begin developing in the first 7 to 8 weeks of pregnancy. They keep growing until week 32, making the entire body responsive to touch. As we develop, we learn to react to tactile senses.

Emotional senses such as the comfort a baby gets from a mother’s touch or the joy we get from a loved one’s kiss. Your defensive senses kick in if you touch something hot. Your sense of touch helps you feel whether something is soft, hard, smooth, or sharp.

We take touch for granted until something goes wrong with it. Imagine if your ability to detect when something is hot did not work. Or if something was sharp and you did not realise it. We would spend our lives with our hands in bandages!

Touch involves so many different sensations, such as pressure, pain, itchiness, warmth, and cold. It also connects to emotions. So, it’s no wonder we don’t fully understand how it all works. It is a complex process. Scientists say humans can live without sight or hearing, but not without touch.

#2 Human Eyes Can Process 36,000 Bits of Information

The human body is a true marvel. If you stop and think about all the things the body does without being told, day in and day out, it makes your head hurt.

Did you know the human eye processes a huge amount of information each hour? It’s one of the most complex and powerful organs in our body.

Thirty-six thousand pieces of information every hour. It can transmit 10 million bits of information per second to the brain. The eye-brain system processes visual data in as little as 13 milliseconds per image. This allows for quick perception. Thirteen milliseconds translates into about 75 frames per second.

To do these amazing feats, your eye has over 2 million working parts. The brain is the only organ more complex than the eye.

You may have heard people claim that animals see better than humans. Actually, that’s not true. Human visual acuity is better than that of many animals, especially small ones.

You assume that your cat can see more frames per second than you can. The reality is that you can probably see details much better than your cat, your dog, or your goldfish, in fact.

However, there are a few animal species with visual acuity that is even better than ours. This includes some birds of prey, which can see up to 140 frames per second.

Not surprisingly, all that processing takes a lot of energy. Your eyes use about 65% of your brainpower — more than any other part of your body. Over 80% of the brain’s processing is related to vision and our eyes.

No wonder we sometimes get headaches behind our eyes!

#3 The Human Nose Can Smell 1 trillion Smells

I know what you are thinking: that is impossible, and how do we know that anyway?

Think about how many different smells you analyse in a day. A cup of coffee, a rose flower, cooking smells, cheese, and wine. They soon add up.

We think of things in such a simplistic fashion. Humans detect smells by inhaling air that contains odours. These bind to receptors inside the nose, relaying messages to the brain. Most scents have many odorants. A whiff of chocolate, for instance, contains hundreds of different odour molecules.

Researchers took 128 odour molecules representing a wide range of smells. They combined them into unique mixtures containing 10, 20, or 30 different components. Next, they got volunteers from the community, aged 20 to 48, for a sniff test of the mixtures.

They crunched the numbers. By looking at how many combinations of the 128 odorants a person can distinguish, they found that the average person can distinguish about 1 trillion smells.

A human nose has around 400 types of scent receptors. The smell of coffee or a woman’s perfume fills the room and triggers specific receptors in the nose. They respond through a neural pathway triggered by the smells.

But don’t get too excited. Although science reports we may be able to detect that many, the brain can only remember and identify maybe 50,000.

This is the basis of wine tastings, an art I have never perfected. I couldn’t tell a berry tone from a liquorice tone or weigh it; it has dark chocolate or white chocolate notes. I would much rather just drink the wine!

I guess you have to train your brain to get in sync with those receptors in your nose. On that note, don’t get too excited. Although science reports we may be able to detect that many, the brain can only remember and identify maybe 50,000.

Whatever we smell, think about a dog. Dogs’ sense of smell is far superior to ours. It’s estimated to be 1,000 to 10,000 times more sensitive. By comparison, there isn’t much a dog can’t smell then. But that is another story.

Hundreds and thousands, millions of tiny cells that interact to give us the joy of living.

Till next time,

Calvin