1. Taste and Smell

2. Chemical Senses – Taste and Smell
Use chemoreceptors
Complement each other
Respond to many of the same stimuli

3. Olfaction – Sense of Smell
Olfactory receptors in roof of nasal cavity
Sniffing intensifies the scent and sense of smell by causing more air to flow across the receptors
Chemicals must be dissolved in mucus for detection

4. Olfaction – Sense of Smell
Olfactory receptor cells are neurons
Have olfactory hairs that are bathed in mucus
When receptors are stimulated by chemicals dissolved in mucus, they transmit impulses along the olfactory filaments

5. Olfaction – Sense of Smell
olfactory filaments make up the olfactory nerve (cranial nerve 1) and then goes to the olfactory cortex of the brain
Brain “memorizes” scent
Olfactory system is closely tied into our emotional system (limbic) so different smells remind us of different situations…good/bad
Olfactory neurons adapt quickly when exposed to unchanging stimuli and we can’t smell it anymore (Ex: restaurant, perfume, household smell, etc)

6. The Sense of Taste Taste buds house receptor organs…about 10,000
Location
Tongue **
Soft palate
Cheeks
Figure 8.18a–b

7. Taste Buds Papillae (aka: projections) Filiform Fungiform**
Circumvallate **

8. Structure of Taste Buds
Gustatory cells are the receptors that respond to chemicals
Gustatory hairs (long microvilli) go through taste pore
Hairs stimulated by chemicals dissolved in saliva
When taste pore is stimulated, they depolarize and impulses are transmitted to the brain through cranial nerves VII (Facial), IX (glossopharyngeal), and X (vagus)

9. Anatomy of Taste Buds
Figure 8.18

10. Taste Sensations
Sweet
Sour
Bitter
Salty