Be Extra Sensitive to Your Senses

AN OVERVIEW OF YOUR FIVE BASIC SENSES

The moment you wake up and get out of bed, your five basic senses start their hard day’s work. That ray of sunshine peeping through the window, the pleasant sound of your alarm clock, the smell of coffee, and the gentle nudge of your partner telling you to get up. All these stimuli are products of interaction between your surroundings, sensory organs, and brain. Your body's ability to see, hear, smell, taste, and touch are innate. These five abilities permit you to perceive, process, learn, and make decisions about your environment. In addition, they solidify your connection with the outside world.

Each of your five primary senses is a part of a sensory nervous system. Visual, hearing, touch, smell, and taste are examples of sensory nervous systems. All of them are integral parts of your peripheral nervous system.

Let’s have an overview of each of these five basic senses:

YOUR SENSE OF SIGHT

We see you

Stand in front of a mirror and look at your eyes. The coloured part of the eye is called the iris. It’s a muscle studded with pigments that modulates the size of the pupil (the hole in the centre). The pupil dilates (increases in diameter) to allow greater light to pass through or contracts (decreases in diameter) to permit less light into your eye. The pupil and iris are covered by a thin layer of transparent tissue called the cornea. The pupil is shadowed behind by an anterior chamber, and at the back of the chamber is the lens. A small and essential muscle attaches to the lens and the iris. This muscle is called the ciliary muscle.

To visualise near and far objects, the lens in both of your eyes becomes rounded and flattened, respectively. This is accomplished through the relaxation and contraction of the ciliary muscles. The process of altering the shape of the lens is termed accommodation. Unfortunately, your ability to accommodate becomes less and less, as you grow older. Enter eyeglasses.

Let’s move a little farther back into your eye. Behind the lens of the eye is filled with a gelatinous substance called the vitreous humour. It gives your eyeball its shape and transmits light to the back of your eye, where the retina is located. This is where the beauty of an object is captured. The retina contains two types of photoreceptors (sensors that detect light):

1. Cones give us colour vision by detecting colour and fine detail. There are three types of cones: red, blue, and green. When one type of cone is missing, colour blindness happens. Cones accomplish their function best in bright light.
2. Rods help provide us with good vision in low light (night vision). They also detect motion and peripheral vision.

Light travels through the pupil, anterior chamber, lens, and into the retina, which contains the rods and cones. Electrical impulses are then generated and conducted through two types of neurons or nerve cells called bipolar and ganglionic cells. The ganglionic cells have nerve fibres that form the optic nerve. The optic nerve then relays the impulse directly to the brain.

That’s interesting. Ommetaphobia (or ommatophobia) is the fear of the eyes. People with this type of phobia don’t make eye contact and don’t touch their eyes. If they see eyes, they feel anxiety, dizziness, sweating, nausea, palpitations, and shortness of breath. Usual triggers for this fear include seeing eye diagrams and having dirt in the eye. Cognitive behaviour therapy is a popular treatment for this type of phobia.

YOUR SENSE OF HEARING

Hear ye, Hear ye

Your ears serve two vital purposes: hearing and maintaining balance (equilibrium). To receive sound, it has to react to mechanical stimulation generated by sound waves. And for it to maintain balance, it has to perceive movement first. Your ear is divided into three anatomical parts: the outer, middle, and inner ear. You perceive sound and balance through the following process:

The outer ear or pinna is the external opening to the ear canal. Sound waves are channelled and amplified in the pinna into the middle ear, where your eardrum is located. When a sound wave strikes your eardrum, the tiny bones attached to it vibrate. The vibration is received by receptors (mechanoreceptors) found on hair-like extensions (cilia) in the inner ear. The cilia move and create an electrical impulse that travels through the fluid-filled cochlea (spiral-shaped small bone) to the auditory nerve. The auditory nerve conducts the impulse to your brain for interpretation.

Let’s not forget about maintaining balance. The movement of fluid in the semi-circular canals is detected by cilia and relays messages to your brain to help your body sustain balance. If the fluid doesn’t stop moving, your brain will have difficulty keeping balance, and you may experience motion sickness

That’s interesting. Does your voice sound different on a recording? When you listen to yourself speaking, your voice travels from your voice box (larynx) up and goes through your skull to reach the eardrums. When you hear it from a recording, the sound of your voice travels through the parts of your ear, making it lower in pitch and slightly different to what you hear by yourself and others.

YOUR SENSE OF SMELL

Your sense of smell or olfaction consists of olfactory cells that are located at the top of your nasal cavity. These cells have two opposite ends. One end has hair-like attachments (called cilia) that protrude into the nasal cavity. At the opposite end are nerve fibres that go into the olfactory bulb structure. You have a pair of olfactory bulbs, and both bulbs are directly connected to your brain.

The olfactory cells are chemoreceptors, which means that they can detect or sense minute differences in the chemical composition of the air you breathe. So, you don’t really smell pollen, dust, or air. What you actually smell is the chemical composition of the air that you breathe, like oxygen, hydrogen, nitrogen, pollen, dust, and other chemicals.

The chemical particles attach to the cilia, which produce an electrical impulse that travels through the olfactory cell, nerve fibre, bulb and ultimately into your brain for processing. Your marvellous brain decides what you’re smelling. If you’re smelling something new, you will need assistance from other senses, such as your sense of sight and taste, to make a lasting mark in your memory.

That’s interesting. We all know how good dogs are at smelling things. But it has been argued that humans are just quite as good as dogs at smelling things. According to research published in the journal Science, humans can differentiate among one trillion distinct odours. Because of our complicated brains, it becomes difficult for us to individually focus on these odours compared to dogs.

YOUR SENSE OF TASTE

Mmm, mmm, that’s terrific

There are chemoreceptors located in the taste buds on your tongue. They’re similar to the chemoreceptors found in your sense of smell. However, the chemoreceptors on your tongue are a bit smarter in that they can determine (and you can consciously perceive these) four different types of tastes: salty, sweet, bitter, and sour.

Look at the mirror and stick out that tongue. No, we’re not amazed that you can reach your chin with it. Just look at the surface. You can see that there are little bumps on the surface. Nope, the taste buds aren’t located on those bumps. They’re actually found in the tiny grooves in between those little bumps. Each taste bud can sense chemicals in the food you eat. A taste bud is equipped with a pore (an opening) and numerous villi (projections) on one end and nerve fibres at the opposite end. The chemicals from the food you eat attach themselves to the villi and create an electrical impulse. The impulse is relayed directly to your brain through nerve fibres.

That’s interesting. Traditionally, we have come to recognise four different tastes: sweet, sour, bitter, and salty. There’s actually a fifth taste, termed savoury, or umami. It’s similar to the taste of meat broth. This is because of aspartic acid or glutamic acid. Aspartic acid is found in meat, cheese, and ripe tomatoes. Glutamate is the salt form of glutamic acid. It’s used extensively in Chinese dishes as a flavour enhancer.

YOUR SENSE OF TOUCH

Because life is touch and go

The body’s largest organ, the skin, contains a lot of receptors. It has receptors for pressure, temperature, pain, and touch. All of them are scattered and working together on your skin. These receptors produce an electrical impulse when stimulated. The impulse travels through your peripheral nervous system and into your spinal cord and brain.

That’s interesting. Based on a research study published by the University of California in Berkeley, your sense of touch isn’t just used to perceive and interact with the world around you. It also has been found to convey compassion from one person to another. When was the last time you consoled someone? You may have subconsciously placed a caring hand on their shoulder or gently squeezed their elbow. That’s the magic of touch.

HOW DO OUR SENSES WORK TOGETHER?

Our five senses seem to work independently as five separate tools for perceiving the world around us. In reality, however, they frequently hold meet and greet short meetings in our brains to better understand our environment. The best way to illustrate this collaboration is to provide some examples.

Imagine a typical barbecue of fresh seafood, sausages, burgers, and steak. In your conscious mind, the delicious taste of these foods immediately comes into the picture. But taste in this context is basically a combination of the food’s smell, taste, and even touch into one major sensation. This mixture of qualities happens because it’s during the biting and chewing that all relevant sensory information originates from one common source. You need the sense of smell to absorb and enrich the food’s flavour and the sense of touch (using your tongue) to appreciate the food’s texture. Without touching the food, you will not be able to taste it. Your sense of taste is the predominant sensation tasked to decipher the chemicals in the food. Don’t forget to open your eyes wide to see the food, and now your sense of vision is added.

Let’s hear some tag-team action between two senses (vision and hearing). Some blind people have acquired the ability to utilise their sense of hearing to construct and map out a picture of their surroundings. This is similar to how bats see in the dark. Bats emit a series of high-pitched sounds that bounce off the walls of the cave. When these sounds return to the bat’s ears, they can determine the location of these walls in relation to the bat’s location in pitch-black darkness. The bat, in a way, can see what it hears.

Do you get startled when you cross the street, and a car honks at you? But why is it that you don’t get startled when you hear a car honking while you’re inside your home? Neuroscientists think that this is because most people interpret sound depending on the immediate visual cues. What you see, your location (home or on the street), determines your response to what you hear. Again, this speaks volumes with regards to how our senses work together.

DISEASES THAT AFFECT OUR SENSES

Several diseases can affect our senses. Below are some examples of common and not so common ones we may encounter or experience.

1. As we grow older, the way our senses provide information about our surroundings changes. Our senses become less sensitive or sharp, which can make it difficult for us to go about our daily lives. Vision and hearing are the hardest hit senses as we age. Luckily, we have hearing aids and eyeglasses to improve our hearing and vision. Unfortunately, our other basic senses aren’t so fortunate (smell, taste, touch).
2. Presbycusis (age-related hearing loss) and tinnitus (ringing in the ears) are common hearing problems among older adults. Click herefor more information regarding other common ear problems. Age-related eye problems include decreased peripheral vision (side vision), dry eyes (not enough tear production), the presence of floaters in your field of vision, and of course, reduction in visual acuity called presbyopia. If you want to know more about other common eye conditions, click here.
3. Squamous cell carcinoma is the most common tongue cancer and usually grows on the sides of the tongue. Smoking tobacco and drinking alcohol are major contributors (risk factors) to the development of this type of cancer. Tongue-tie or ankyloglossia is a congenital condition caused by a shorter than average structure beneath the tongue (called frenulum). The short structure prevents tongue protrusion and makes it difficult for infants to breastfeed. By the way, on the subject of medical conditions of the tongue, gossiping is not a tongue disorder. To know more about your tongue, click here.
4. What do anosmia and hyposmia mean? Anosmia (inability to smell) and hyposmia (decreased ability to smell) describe the range of smell disorders. Causes of these smell disorders include old age, infections like viral illnesses, allergic rhinitis, nasal polyps, head trauma, and even schizophrenia and depression. Your sense of taste may diminish if you don’t have an intact sense of smell.
5. As mentioned above, your skin is home to receptors for pain, temperature, pressure, and touch. Congenital insensitivity to pain with anhidrosis, or CIPA for short, is a rare genetic condition wherein a person is unable to feel pain and temperature in different parts of the body, especially the skin. This is dangerous because it makes the person more prone to accidents because of the inability to feel pain (touch perception is present, but not pain perception). Click here for other examples of diseases that affect your sense of touch.

The senses discussed in this article are the five basic ones. There are other senses in our bodies that interact with each other to provide more sensory input for our brain and body. All of these senses work instantaneously and involve complex processes. There’s no single, absolute, and logical way to define each sense. In essence, you don’t really need to define them strictly, but you need to remember the fantastic work they do for you in your life, making it more vivid and alive.