TASTE BUDS OF THE TONGUE ::
The receptors for the sensation of taste are the taste buds located on the sides papillae of the tongue (Refer for details the digestive system )
A fewr taste buds are located on the soft palate epiglottis and pharynx Taste buds are classified according to the stimulus that causes the maximum response There are four basic types of buds classified according to the taste sensation bitter sour salt and sweet The taste buds serving the four sensations do not respond equally to the same degree of stimuli Listing taste sensitivity from the greatest to the least bitter is followed by sour salt and sweet
The taste buds are oval clusters of cells oriented vertically in the epithelial layer with a small pore on the surface They are 60-80 u in length and 40 u in diameter The cells within taste buds are of two types gustatory or taste cells or hair cells and supporting cells The nerve fibres arise from the hair cells and from a nerve plexus near the basement membrane and finally join with IX (glossopharyngeal ) or facial nerve Taste buds are surrounded by stratified squamous epithelium of the tongue
Different areas of the tongue are more sensitive to some tastes than to others The tip of the tongue is more sensitive to sweet the back to bitter the sides to sour and both the tip and sides to salt The anterior two -thirds of the tongue is innervated by a branch of the facial nerve and the posterior third by the glossopharyngeal The vagus nerve receives impulses from the throat and pharynx
Nerve impulses are conducted over these pathways to the taste center in the medulla from the taste center connections are made with the thalamus and cerebral cortex In the cortex impulses are interpreted as the sensation of taste The taste sensation stimulates reflexly the secretion of saliva and digestive juices
To create the sensation of taste a substance must be in the solution form so that it can have contact with the receptors between the papillae on the tongue one of the functions of saliva is to dissolve substances so that they may enter the taste pores and stimulate the receptor The sensation of taste may be diminished if the flow of saliva is limited impairment of the sensation of taste can also be the result of poor oral hygiene if the papillae are covered over with a coating called sordes
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