Special Sense Organs: Tongue.
Introduction:
Sense of “Taste” is called “Gustation”.
The tongue is a muscular organ in the mouth that manipulates food for mastication and is used in the act of swallowing.
It has importance in the digestive system and is the primary organ of taste in the gustatory system.
Tongue consists of about 10000 taste buds.
The taste buds are present in elevations on the tongue called papillae.
There are three types of papillae.
1) Vallate papillae
2) Fungiform papillae
3) Filiform papillae
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1) Vallate papillae
About 12 large, circular papillae form an inverted V-shaped row at the back side of the tongue.
Each of these papillae consist of 100-300 taste buds.
2) Fungiform papillae
It is mushroom shaped elevations scattered over the entire surface of the tongue.
Each papilla consists of 5 taste buds.
3) Filiform papillae
These are thread-like structures which increases friction between the tongue and food.
It also facilitates movement of food in the oral cavity.
Tastes:
Five primary tastes can be distinguished as sour (आंबट) , sweet (गोड), bitter (कडू), salty (खारट) and umami (तुरट) (meaty/savory).
All other tastes are a combination of the two or more of the five primary tastes or are associated with olfactory sensation (smell).
Certain chemicals stimulate gustation receptors.
Nerve impulses are generated and conducted towards the taste area in the parietal lobe of the cerebral cortex where the taste is perceived.
The stimulation of different tastes takes place at different parts of the tongue.
1) Sweet and salty taste mainly at the tip of the tongue.
2) Sour taste at the sides of the tongue.
3) Bitter taste at the back of the tongue.
4) Umami tastes in several regions of the tongue.
Physiology of taste:
Taste buds contain sensory receptors (chemoreceptors) that are found in the papillae of the tongue and widely distributed in the epithelia of the tongue, soft palate, pharynx and epiglottis.
They consist of small sensory nerve endings of the glossopharyngeal, facial and vagus nerves.
Some of the cells have hair-like microvilli on their free border, projecting towards tiny pores in the epithelium.
The sensory receptors are stimulated by chemicals that enter the pores dissolved in saliva.
Nerve impulses are generated and conducted along the cranial nerves to cerebrum where interpretation of taste takes place.
Commonly Asked Question.
Write a short note on Sense of Taste.