The Special Senses Taste and Smell Taste taste

The Special Senses: Taste and Smell

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 Taste

• 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)

• 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

4 Sensations • sensitivity varies according to region of tongue 1. sweet - carbohydrates and amino acids, tip 2. sour - acids, sides 3. bitter - alkaloids, back 4. salty - metal ions, more even

4 Sensations • sensitivity varies according to region of tongue 1. sweet - carbohydrates and amino acids, tip 2. sour - acids, sides 3. bitter - alkaloids, back 4. salty - metal ions, more even

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

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

Hot foods trigger pain receptors - chili peppers.

Smell Olfaction

Smell • located in olfactory epithelial lining the roof of the nasal cavity

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

• 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

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

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