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Renin Angiotensin Mechanism.

Special Sense Organs: Tongue

 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

  • 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.

  1. Write a short note on Sense of Taste.
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