1. Taste, Smell & Touch Lecture
Chapter 8

2. Sense of Smell
Air enters nasal cavities where olfactory receptors in roof of nasal cavity are stimulated and pass message to olfactory nerve

3. Olfactory pathways are closely linked to limbic system
Odors recall memories and arouse emotional responses

4. Sense of Taste Taste buds (Gulfactory cells)
Receptors for taste located on the tongue
Located around tongue papillae
circumvallate (back of the tongue)
fungiform (primarily on sides and front of tongue))

5. Five Basic Taste Sensations
Sweet receptors
Sour receptors
Bitter receptors
Salty receptors
Umami receptors
Meaty/savory/texture
Did you know…
“Hot” spicy foods actually activate the pain receptors in your tongue and give you the sensation of heat in your mouth

6. Food must be dissolved in water to be “tasted”
Purpose of saliva
There are 2 nerves that relay the signal of taste to the brain
Facial nerve: anterior 2/3 of tongue
Glossopharyngeal nerve: posterior 1/3 of tongue

7. Touch
Only sense that is not localized to one region of the body

8. Bottom layer of skin (dermis) contains nerve endings that sense touch and send signal to spinal cord and then to the brain
Most common nerve endings are for:
Heat
Cold
Pain
Pressure

9. Some areas of the body contain more nerve endings and therefore are more sensitive to touch
Examples: face, hands, feet, tongue

10. Touch receptors Most common:
Thermoreceptors (heat & cold)
Pain receptors
Mechanoreceptors (pressure & texture)
Receptors are not evenly spaced throughout body (some areas have more or less of each of the different types of receptors)