Tongue & Taste – Taste – Delight of food
Food is very essential for energy for our existence. Tasty food tempts us to eat. Taste is one of the special senses / feelings just like vision , hearing, smell, touch or pain . Each and every one has their own favourite taste. Parrots like chillies, rabbits like carrots, dogs like bones, children like ice creams / chocolates / sweets, etc.
Taste will help us choose the right quality food. Of course, it can also become a culprit in making one obese
with high cholesterol with good eating. Taste differs from person to person and also time to time even in the same individual. Usually, some food tastes good and some others might be tasteless. Without taste, no one will have interest in food and it may lead to disgust for it. Taste improves the appetite and also protects us from most bitter / corrosive substances by creating aversions.
Normally, desires and aversions are developed with habit, i.e., what some find delicious might be not be so for others. Nowadays, evolution of cooking and revolution of catering technology has been creating / introducing many varieties of food items claiming to be mouthwatering, delicious. Everyone likes to have sweets (mostly), as sugar and carbohydrates are most essential foods. But we can see personalities who crave for salty / sour foods / bitter things too. These cravings sometimes make the persons aggressive too, for example – children become aggressive and stubborn in getting chocolates, likewise, a dog might become aggressive for getting meat even if it has got milk.
One will not feel any taste beyond the pharynx, even then those tempting temporary moments make everyone to have good intake. Even though appetite is entirely different from taste, for good intake, it seems to be essential.
Taste buds and receptors – Feeling of taste is sensed by taste buds / receptors present all over the mouth in a scattered manner (i.e., in tongue, walls of cheek, gums, back part of pharynx and soft palate). Taste buds are actually a cluster of epithelial cells present around a central pore in the papillae. In the tip of the each taste bud, there will be hair / receptors to sense the taste of the substance which comes in contact with it. But, they get destroyed often since they are exposed to different types of food substances which includes concentrated acids (juices), alkali (salts), corrosives (preservatives), etc., and their life is short i.e., maximum 2 weeks. Anyhow, they are constantly renewed.
The tongue has 4 types of papillae. They are scattered in different areas and engaged in identifying specific tastes. They are:
- Fungiform papillae – concentrated more in anterior one third of the tongue (identify sweet taste more quickly than others)
- Circumvallate papillae – concentrated more in posterior two third of the tongue (identify bitter taste more quickly than others)
- Foliate papillae – concentrated more in lateral borders of the tongue (identify sour / salt taste more quickly than others)
- Filiform papillae – have no taste buds.
Parts of the tongue which are sensitive to specific taste are:
- Sweet – tip of the tongue
- Sour – sides of the tongue
- Bitter – back part of the tongue
Chemically sensitive taste buds identify the particular taste of the food substance and trigger the particular area in brain (cerebral cortex) to have a pleasant or irritable feeling. These types of special sensations are carried to the brain by VII cranial nerve – facial nerve – chorda tympani branch (from cheek and anterior 2/3 of tongue) and IX cranial nerve – glossopharngeal nerve (from posterior 1/3 of tongue, gums and pharynx).
Variation in taste – Taste is a feeling (pleasant taste / unpleasant taste). It often varies with many factors. Taste is usually coordinated with olfaction / odours. So any dysfunction of it can also reflect in taste. While masticating, different food substances come in contact with taste receptors and can cause variation or confusion in taste discrimination. Also, due to overlapped fields in cerebral cortex (of brain), taste cannot be fixed as certain by individual, so perception and adaptation commonly varies from person to person and sometimes in the same individual. Taste may be enhanced by tongue movements, which increase the distribution of the substance over a greater number of taste buds. Taste may differ (lowered or altered) with
- Strong tooth paste, mouth fresheners, betel leaves, tobacco, cigarettes, etc.
- Poor oral hygience, tongue coating and lack of proper brushing
- Physiological changes (pregnancy – craves sour / salt – since body needs more salts)
- Pathological changes – Diseases (especially upper respiratory tract infection, viral flu, stomatitis, nerve leisons, hormonal / endocrine disorders, etc.)
- Treatments like chemotherpy, radiation therapy, etc.
- Olfaction disorders – nose polyp / block, sinusitis, post nasal drip, allergy , etc.
Brain dysfunctions (in taste areas)
In addition environment, colour / attraction / proper serving of food can also add flavours Taste will also differ from previous substance tasted, for example
- After taking goose berry, water will taste sweet
- After taking gymnema (sakkarakolli) leaves, you cannot realise the sweetness of any sweet
- Water may taste bitter or sour after getting accustomed to extreme salty foods.These may be due to a suppressing or an opposite effect.
Taste reflexes and taste provoking smells
(increased drooling, salivation) can be seen with delicious food intake (even with smell or sight too). As a reflex, concentrated sour taste will induce increased salivation instantly (to enhance fast intake of it as salts are vital for the body). Also most bitter taste too will induce increased salivation (to reduce the concentration of bitter substance / bitterness to comfort the tongue).
All the taste buds will usually respond to more than one taste. As food substances have different taste substances, every taste bud will initiate taste stimuli to the brain. But, when they get contact with specific taste buds, they will initiate enhanced (pleasant or unpleasant) stimuli to the brain. Also many of the flavours are recognised more with the sense of smell, i.e., if one holds his nose while eating / drinking, he could not be certain in telling the exact taste of it. Likewise, even the smell of coffee can induce the taste of coffee in brain, since flavour of the coffee (or food) will also be exhaled through the nose with our natural respiration.
Taste disorders – Even though taste is not only confined to the tongue, the tongue is always blamed for any taste difference or variations. Taste buds / receptors in the tongue are very much sensitive to temperature or disease, so any change in body with oral temperature or disease will have taste variations too. Taste disorders are named as:
- Ageusia – Absence of taste (complete loss of taste buds / nerve functions)
- Dysgeusia – Inappropriate / inaccurate taste – (malfunctions of nerves)
- Hypogeusia – diminished taste sense (partial loss of taste buds / nerve functions)
- Parageusia – irritating or unpleasant sense of taste
These terms can be used only with complaints or feelings of the sufferer. Even though taste function test – spatial test – can analyse the taste variation, it cannot be tested easily as done for other special senses (vision or hearing). Also there is no scale for intenstiy or concentration of taste. In addition, complicated design of taste testing will not provide accurate results.
Dr. S. Chidambaranathan, BHMS, MD (Homeo)
24 E. New Mahalipatti Road
Tel: +91-452-233-8833 | +91-984-319-1011 (Mob)
(Disclaimer - The contents of this column are for informational purpose only. The content is not intended to be a substitute for professional healthcare advice, diagnosis, or treatment. Always seek the advice of healthcare professional for any health problem or medical condition.)