Smell and Taste

Anatomy of the olfactory receptors Olfactory epithelium Olfactory receptors are localized on the roof of the nasal cavity. Covered by mucus. Bipolar neurons with cilia Supporting cells Basal cells – stem cells Olfactory glands Responsible for mucus production

Anatomy of the olfactory receptors Olfactory nerves Penetrates the ethmoid bone Olfactory bulb Olfactory tracts Cerebral cortex – uncus Olfactory adaptation Partial adaptation: 3-5 seconds Complete adaptation: 1-5 minutes

Olfactory organs

Anatomy of Taste Buds

Taste receptors – gustatory cells Clustered in taste buds Associated with lingual papillae Types of lingual papillae Filiform- The more numerous one. No taste buds Fungiform – mushroom-like. Contain taste buds Circumvallate- on a V formation on the back of the tongue. Contain taste buds

Taste buds Basal cells Supporting cells Gustatory hair Taste pores Stem cells Supporting cells Insulate the gustatory cells Gustatory hair Seems to be the sensitive portion of the taste cells They are microvilli Taste pores Opening for the gustatory hair

Gustatory reception

Gustatory pathways Taste buds are monitored by cranial nerves Facial – anterior 2/3 of the tongue Glossopharyngeal- posterior 1/3 of the tongue Vagus –taste buds on the pharynx Synapse within the solitary nucleus of the medulla oblongata Thalamus Trigeminal – will carry all the other information such as texture, and temperature

Taste buds distribution Sweet receptors Sugar and some aminoacids Salt Metallic ions Sour Acid solutions Bitter alkaloids Umami Cheese, meat taste

Gustatory discrimination Combine effects of smell, texture and temperature on taste