Digestive ppt. III

A deep groove encircles the body of the circumvallatepapilla.
•Serous (von Ebner’s) glands (serous) drain into the base of this groove.
•The flow of fluid from these glands serves to wash surface of the papilla and clean materials from taste buds so they are ready for new gustatory stimuli.
•Other serous and mucous glands in other parts of oral region serve the same sort of purpose for cleansing other types of papillae
Taste buds
a. Oval multicellularstructures
b. Cells surround a cavity that communicates with the oral cavity via a small pore between the apexes of the cells.
c. Dissolved substances enter the cavity through this pore and come into contact with the microvilliof gustatory cells(neuroepithelialsensory cells) of the taste bud.
d. These chemical stimuli are transducedto an electrical impulse that is transmitted through afferent axons of cranial nerves 7, 9, and 10 that synapse on the basal portions of the neuro-epithelial cells.
e. Action potentials travel along these axons to the portions of the brain responsible for our sense of taste.
f. Taste buds are composed of 3 cell types
* Gustatory (taste) cells
* Sustentacular(support) cells
* Basal cells -stem cellsfor replacement of gustatory cells
** gustatory cells live for about 7-10 days
g. Both gustatory and sustentacularcells have similar structure, long microvillithat extend into the lumen of the taste bud.