*Taste:-
-taste receptor are chemorecepter-the chemical substance in food ,dissolves in saliva and comes in contact with hair cell cilia of the recepter.
-fast adapting recepter-stimulus is continuesly given to the subject the sensitivity of that substance is reduced .
-recepter prevent in the taste bud -taste bud which is distributed in pappillae ,which is present in tongue ,oral cavity ,pharynx.
-primary taste sensation >:-sweet ,salt,sour,bitter.
+sweet-appreciated more at the tip of the tongue.
+salt-appreciated at the dorsum of tongue.
+bitter-appreciated at the base of tongue.
sour-appreciated more at the edges of the tongue.
-recepter cells-
-it has a microcillia at the apex which projects taste pore.
chemical substance dissolves in the saliva,when it come near the taste pore,the receptor cells get depolorised recepter potential is developed .
-the nerve fibers at the base carry the sensation and which form the gastationary nerve.
-supprting cells/basal cells-they helps in form of new recepter cells when old recepter cells perishes.
abnormal condition of taste:-
1)hypogensia-decreases taste sensation
2)agensia-absence of taste sensation.
3)dysgensia-disturbed taste sensation.
eg:-antibiotic treatment,bitterness.
Taste pathway:-
-anterior 2/3of tongue -sensation is carried by chorda tympani branch of vii cranial nerve.
-posterior 1/3 of tongue -taste sensation is carried by ix cranial nerve.
-and from the pharynx taste sensation is carried by x cranial nerve.
-the gustatory nerve I st order synapse at nucleas of tractum solitarius at the medulla oblangatta .
-The II nd order neuron arise from nucleus of tractum solitarius ascends up and relays in thalamus.
-the III order neuron arise from the thalamus ,terminates at the area no.43 at the base of temporal nerve.
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