1. CHAPTER 14 SECTION 14.1 SENSORY INFORMATION

2. Sensory receptors
Sensory receptors –are highly modified dendrites of a sensory neuron that are activated by an environmental (internal or external) stimulus.
A stimulus is a form of energy.
Sensory receptors convert one source of energy into another.
Taste receptors in your tongue convert chemical energy (dissolving food) into electrical energy (action potential).

3. SENSORY RECEPTORS CONT’D
Light receptors in your eye converts light energy into electrical energy.
Balance receptors convert gravitational potential energy and mechanical energy into electrical energy.
Sensory receptors are usually specialized based on their sensory organ (eye,ear, etc.)

4. The Body’s Sensory Receptors
Receptor Type
Stimulus
Information Provided
Taste
Chemical energy
Presence of specific chemicals (identified by taste buds)
Smell
Presence of specific chemicals (identified by olfactory cells)
Pressure
Mechanical energy
Movement of skin or changes in body surface
Proprioceptor
Movement of the limbs
Balance
Body movements
Audio
Sound
Sounds waves
Visual
Light energy
Changes in light intensity, movement and colour
Thermoreceptor
Temperature changes
Flow of heat

5. Sensory adaptation
Sensory adaptation – occurs once you have adjusted to a change in the environment; sensory receptors become less sensitive when stimulated repeatedly.
Ex. When you climb into a hot shower, immediately the water feels very hot, however after 30s to 60s your body adjusts to the temperature and the water does not feel as hot, even though the temperature has not changed.
Ex. If a strong smell persists in a classroom (formaldehyde) by the end of the class you will become accustomed to it.

6. taste
Taste receptors allow you to differentiate between things that are edible and things that are inedible.
Taste receptors are found in different locations in different species. (Humans – tongue vs. Octopus – tentacles)
In humans, taste receptors are concentrated on our tongue and detect chemicals in food.
They detect only chemicals that have been dissolved by saliva.

7. TASTE CONT’D We have 4 main types of taste: - sweet - sour - salty
- bitter
Different sections of our tongue are responsible for detecting the different types of taste.

8. Taste areas on tongue

9. smell
Smell receptors are responsible for detecting airborne chemicals.
Our smell receptors are concentrated in olfactory cells lining our nasal passageways.

10. Taste and smell working together
Taste and smell work together.
Clogged nasal passageways reduce the effectiveness of olfactory cells.
If mucus in your nasal passages becomes too thick, air and odor molecules can’t reach your olfactory receptor cells. Thus, your brain receives no signal identifying the odor, and everything you eat tastes much the same. You can feel the texture and temperature of the food, but no messengers can tell your brain, “This cool, milky substance is chocolate ice cream.” The odor molecules remain trapped in your mouth. The pathway has been blocked off to those powerful perceivers of smell--the olfactory bulbs.