Feed Your Senses!!!

Updated: Mar 10, 2021

Sarthak Jain, Hrishik Mukherjee, and Devesh Kumar Yadav,

St. Xavier's College (Autonomous),

Mumbai, Maharashtra, India

 
Humans have evolved with time, be it in terms of body structure or be its senses.


We, humans, have five basic senses viz: sight, sound, smell, taste, and touch. Over the years' humans have evolved with powers to distinguish and determine the two extremes of all of them. Some of the senses have a broad spectrum of a range such as eyesight which can detect in the range of 400 -700 nm or sound with an audible frequency range of 20Hz- 20KHz, on the other hand, we have senses which can detect and distinguish only a certain type of sensors such as our “sense of taste" which is capable of detecting maximum five different tastes. Still, one of the most undervalued senses we humans have has always been the "sense of smell". This sense is often being regarded as one of the most unrefined and unevolved senses though many theories have certainly defined the ability of the human nose to detect one trillion different odors.

All of the human senses work in more of a similar mechanism such as our 'sense of taste' or 'tongue' is divided into five different sections with the ability to determine sweet, bitter, sour, salty, and savory. Each of the taste buds has consisted of 50-100 taste receptors (or a.k.a. taste cells) due to which ability to determine and differentiate can be defined. Similarly, for the 'sense of sight', as soon as the light of high intensity falls on the eye it sends electrical impulses to the brain and the brain in return sends the command which is sometimes also seen as the retina undergoing a reflex action.

Let's talk in a bit detail about each sense we are gifted with:


Ear:


The human ear is a very remarkable device with the ability to sense frequency range from 20 Hz to 20 kHz and higher-pressure fluctuations (a million times!). It is divided into three main parts viz, the Outer ear, middle ear, and inner ear. The inner ear contains the cochlea in which the organ of Corti resides. The liquid in the organ of Corti, situated at the top of the basilar membrane has a high potassium ion concentration whereas the one situated at the bottom of the membrane has low potassium ion concentration causing a potential difference. When any sound of a particular frequency hits the ear, it leads to the bending of the hair cells present over there which then sends electrical impulses to the thalamus of the brain.



Eye: It all starts with the retina of the eye which undergoes excitation and a series of chemical reactions after absorbing light waves from the visible spectrum range (400 nm - 700 nm) which send stimulus to neurons and nerve fibers of the brain thus creating the perceived image. It seems simple but in reality, it is the involvement of cascades of chemical reaction that help in it. Basically, the retina possesses Vitamin A (Retinol) which gets transformed into Retinal (from alcohol to aldehyde). When light wave irradiates the cis-retinal, it gets isomerized to trans-retinal which then further changes to a protein complex. These geometrical changes in the structure of the molecule lead to the formation of the potential difference which then generates electrical impulses which are sent to the "Thalamus" of the brain and thus image is perceived.

Taste: Sense of taste is controlled by a cluster of taste receptor cells, which are collectively called, taste buds. Various chemicals are used as references to distinguish the taste between two substances. The saliva consists of some part of sodium and the food substances having larger concentration led to the diffusion of sodium thus depolarizing the taste cells giving the sensation ‘salty’ (as in NaCl – salt). If the substance contains acids whose concentration is greater than the H+ ion content in the saliva, a similar procedure takes place and gives the sensation of ‘sour’. Now, bitter, sweet, and umami tastes follow a slightly different mechanism. Instead of the diffusion process, they undergo binding with the G-protein cells. ‘Sweet’- more affinity to bind with the G-protein cells than glucose in the saliva. ‘Bitter’- having the presence of alkaloids that do not bind to the G-protein cells as much. Too much alkaloid presence leads to gag-reflex, a protective mechanism (as alkaloids are very toxic). Umami- amino acids bind to the G- protein complex.

Touch: A recent study has suggested that perception of position and movement of the body or the sensation of touch is mainly mediated by some protein families present in skin cells. Two such members are Peizo1 and Peizo2 ion channel proteins which show response when mechanically stimulated. In fact, it is the Piezo2 channel that influences the sensation of touch. These proteins are typically different in their structure and amino acid sequence which confers them a unique ability for detecting mechanical touch which is then taken care of by the "Thalamus'' of the brain.


Smell: While the "Thalamus" of the brain takes care of the four senses viz, sight, sound, taste, and touch, "Limbic" forms the Central Processing unit for the last sense 'smell'. This part of the brain takes care of emotions, feelings, moods, sexual behavior, and memory. The process of smelling and detecting an odor takes through a combined system called an olfactory system which then has an olfactory bulb. Each bulb has small hair-like things called "primary neurons" which are then connected to the Limbic of the brain using the olfactory nerve.


Imagine, what if we don't have such a complex mechanism taking place in our body!?! Will it affect our routine life?? Umm… Can't say much, right? Well…We can help you...

Imagine one day, if you lose the sense of sight. What you would be imagining now would be- ‘complete darkness and a discolored world’, you won't be able to see your loved ones and not your favorite and pictured memories. Now, you must be wondering, how specially-abled people feel in their environment in case of vision loss? Wait till you get an answer.

And what if…

You wake up one day and find out that you can't hold things or walk due to a foot drop or some altered sensation in the legs. It's like living in your worst nightmare. It may feel like, you have gained some super ability at first to not be able to feel any pain, but the relative nerve pain and inability to feel temperature and pain in case of injuries will deteriorate the injuries and which will, later on, reduce your work efficiency and strip you of some of the best enjoyments in your life and you would wish that this never happened. But what about people who face this…? Wait till you get an answer.

Also….

Have you ever wondered what would happen if you were to lose your hearing ability? Various effects arise from this. Studies have shown that people without hearing capability are more prone to depression than ones with hearing capability. Due to loss of hearing, making conversations also become difficult instilling a sense of isolation which catalyzes the effects of depression by a huge amount. Hence, hearing loss most often is associated with the declination of efficiency along with cognitive impairment. But what about people who face this…? Wait till you get an answer.

Well, losing your sense of feeling, hearing, and seeing can be scary but losing your sense of taste, strips off all your pleasure to enjoy a good meal. It will also hamper your ability to detect spoiled foods and detect the amounts of alkaloids present in your food (bitter, remember?) preventing your body to undergo the gag reflex and your body will be completely vulnerable to unregulated amounts of toxic chemicals entering it. In fact, in today's scenario, it will also probably mean that you may have contracted COVID. Unfortunately, it cannot be prevented by any means available and you have to see a doctor if this happens. It is easily detectable and assessing it at the earliest will be a very wise thing to do.


Wait till you get an answer, well, here is the answer:

For the fact being, in the case of people with visual and hearing impairment, other senses usually compensate for the sense which is lost. For example, in the case of vision impairment, other sensory organs come up together to compensate for it and our tactile (touch), smell, and hearing ability increases in such cases for better navigation, but again all these processes take time and considerate practice.


Seems Fair, Right!?!


Don’t you hurry…

We have senses which can't be compensated for, such as our sense of touch or sense of taste. For example, a green-colored fruit can be seen, touched, or smelled but we still can't define its taste until and unless we put it in our mouth, and losing the sense of taste can defy us from this ability.


Though sounds complex, senses are the building blocks of our life, and life would have been very different without any one of them, be it any. Thus, our life revolves around the functioning of these senses and can't be replaced. So, make sure to:

Feed your senses with utmost care instead of exploiting them.

References: -

1.https://chem.libretexts.org/Bookshelves/Biological_Chemistry/Supplemental_Modules_(Biological_Chemistry)/Photoreceptors/Chemistry_of_Vision

2. https://www.chemistryworld.com/features/the-proteins-of-touch/3007645.article

3.http://www.vivo.colostate.edu/hbooks/pathphys/digestion/pregastric/taste.html#:~:text=The%20sense%20of%20taste%20is,to%20centers%20in%20the%20brainstem.&text=The%20microvilli%20of%20the%20taste%20cells%20bear%20taste%20receptors.


4.https://courses.lumenlearning.com/austincc-ap1/chapter/special-senses-taste-gustation/

5. https://www.nytimes.com/2020/04/17/parenting/sensory-processing-disorder-kids.html

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