1. The Special Senses: Taste and Smell

2. Taste

3. Taste
taste buds contain chemoreceptors that respond to chemicals in a aqueous solution
most taste buds are on the tongue, a few are on the palate, cheeks, pharynx

4. taste buds are located on the sides and tops of papillae
3 types of papillae and only 2 have taste buds
fungiform (tops)
circumvalate (sides)

6. taste cells have hairs protruding that are stimulated
each bud is globular with supporting cells and taste cells (gustatory cells)
taste cells have hairs protruding that are stimulated
the other end of the taste cell stimulates a nerve ending that will carry taste information to the brain

7. 4 Sensations sensitivity varies according to region of tongue
sweet - carbohydrates and amino acids, tip
sour - acids, sides
bitter - alkaloids, back
salty - metal ions, more even

8. 4 Sensations sensitivity varies according to region of tongue
sweet - carbohydrates and amino acids, tip
sour - acids, sides
bitter - alkaloids, back
salty - metal ions, more even

9. Most buds respond to several tastes. Taste is 80% smell.
Subtle flavors are the result of aromas passing through the nose

10. The mouth also contains thermoreceptors and mechanoreceptors that detect temperature and texture
ex: “gritty pear”
“pasty avocado”

11. Hot foods trigger pain receptors - chili peppers.

12. Smell
Olfaction

13. Smell
located in olfactory epithelial lining the roof of the nasal cavity

15. Olfactory hairs on the ends of receptor cells are covered with mucous which serves as a solvent for odor molecules.

16. we have 15 - 30 kinds of receptors and can distinguish 10’s of 1000’s of smells
chemicals must be volatile (gas) and water soluble in order for us to smell them

18. sense of smell fades quickly due to inhibitory influences in central olfactory pathways to the brain - not receptor response.

19. Smell triggers emotions and memories because olfactory nerves go directly to limbic system.