Anatomy and Physiology of Children and Adolescents - M. R. Sapin 2007

Sense Organs. Analyzers
Organs of Taste and Olfaction
Organ of Taste. Gustatory Analyzer

The perception of taste and smell plays a vital role in human life. Taste and odors provide valuable information about food quality and the environment, while significantly influencing a person's emotional state and behavior.

Sensations of taste and smell are triggered by the action of chemical compounds on specialized sensory Cells within the Organs of taste and Olfaction.

The human ORGAN OF TASTE is represented by numerous (approximately 2,000) taste buds located in the Stratified Epithelium of the mucous membrane of the Tongue, soft palate, Pharynx, and epiglottis. Taste buds are particularly abundant in the epithelium of the filiform, fungiform, foliate, and vallate papillae. Ellipsoid in shape, taste buds consist of tightly packed receptor (gustatory) and supporting cells. At the apex of each taste bud lies a taste pore that opens into a small taste pit bounded by the tips of the gustatory cells. The surface of each taste Cell facing the taste pit features microvilli. Sensory taste cells perceive sweet, sour, bitter, salty, or combinations of these four primary taste stimuli. To stimulate taste cells, these substances must be dissolved in a liquid; saliva serves as this solvent in the Oral Cavity. The dissolved substance enters the taste buds through the taste pores at their apices and excites the gustatory cells. This excitation is transmitted to adjacent nerve endings, generating a Nerve Impulse. The nerve impulses travel via nerve fibers entering the taste bud up to the Brain. Impulses from the anterior ²/₃ of the tongue are transmitted along the nerve fibers of the lingual nerve, and subsequently via the fibers of the chorda tympani of the Facial Nerve. Impulses from the vallate papillae, soft palate, and palatine arches pass along the fibers of the Glossopharyngeal nerve, while those from the epiglottis travel via the Vagus nerve fibers.

The Cell bodies of the first-order Neurons of the gustatory pathway reside in the sensory ganglia of the VIIth, IXth, and Xth cranial nerve pairs. The axons of these cells travel within the aforementioned nerves to the Nucleus of the solitary tract located in the Medulla Oblongata, where the nerve fibers terminate in synapses on the cell bodies of its neurons. The central processes of these Nerve Cells then project to the thalamus. Axons of thalamic neurons extend to the cortical center of the gustatory analyzer, located in the cortex of the parahippocampal gyrus, uncus, and hippocampus (Ammon's horn).

Connections with the cortical structures of the limbic system drive the motivation behind feeding behavior.