1. Special Senses: Olfaction, Taste and Vision
Exercise 26, 25, 24 in the lab book

2. Types of Sensory Receptors
Chemoreceptors – detect chemical cues
Ex: taste and smell
Mechanoreceptors – detect stimuli via a
mechanical distortion of a cell membrane
Ex: hearing and touch
III. Photoreceptors – detect light
Ex: vision

3. Smell (Olfaction) Chemoreceptors in the olfactory epithelium
respond to chemicals

4. Olfactory Nerve
Olfactory
Epithelium

5. Taste The tongue’s surface is covered
by small projections called papillae
Papillae contain the taste buds
There are 10,000 taste buds on the human tongue
Each taste bud has ~100 taste cells

6. Taste Pore

7. Taste
Chemicals in food are detected by taste cells located in the taste buds
Taste Cells
Taste Bud

8. Taste Activities Locate the papillae on your tongue – Pg. 399
Do Activity 3: Stimulating the taste buds
Can you taste the sugar?

9. The Distribution of Taste
Sweet, Sour, Salty, and Bitter
There is now 5th “taste”
Umami is the distinctive taste
found in meat and cheese
Led to the creation of MSG
as a seasoning/preservative

10. Plotting Taste Bud Distribution Does YOUR tongue match this pattern?
Hi, I am Kikunae Ikeda. I
discovered Umami in 1907.
You can blame MSG on me.

11. Taste Activities Do Activity 4: Effect of smell on taste
Fill out the table on Pg. 401
Do Activity 5: Importance of taste and olfaction
on odor identification
Fill out the table on Pg. 402

12. Hearing
Outer Ear
Middle Ear
Inner Ear

13. Middle Ear Bones:
Malleus, Incus, and Stapes
Tympanum
Semicircular Canals
Cochlea
Auricle
(Pinna)
External Acoustic
Meatus
Auditory Tube
(Eustacean Tube)

14. Hearing Hearing involves mechanoreceptors in the ear
Sound waves vibrate the tympanum (eardrum)

16. Ear Infection (Otitis Media)
Inflammation of the mucosal membrane in the
middle ear
Commonly caused by bacteria from a sore throat
middle ear & throat are
connected by the auditory
tube

17. Sensory Adaptation
All senses “adapt” to stimuli
Test with sound

18. pupil

19. Sclera
Iris
Pupil
Cornea
The pupil will change size with light condition

20. The Rods and Cones These are the photoreceptors of the eye
They occur in the retina of the eye
120 million rods and 6 million cones in each retina
Rods are specialized for low light conditions
Cones are specialized for color vision under high
light intensity

21. The Blind Spot Do Activity 5: Demonstrating the Blind Spot
Why do you have a blind spot?

24. The Causes of Near/Far Sightedness
Lens over or under compensates when focusing
Eyeball is too long or too short for proper focusing
Cornea or lens has improper curvature

25. Cataract Lens is hard and opaque
Causes problems for focusing light on the retina

27. Glaucoma Aqueous humor is constantly being created and
drains from the eye
Blockage stops drainage, putting pressure on the
retina & optic nerve

29. Astigmatism Irregular curvature to the cornea or lens causes
focusing problems

30. Other vision tests: Astigmatism Binocular Vision
Do Activity 8: Testing for Astigmatism
Do Activity 10: Testing for Binocular Vision

31. Color Blindness
Normal Vision
Color Blind

32. What Causes Color Blindness?
There are 3 Types of Cones in the Human Eye:
Red Cones for red wavelengths of light
Blue Cones for blue wavelengths of light
Green Cones for green wavelengths of light
Color Blindness occurs when one or all of these
cone types are not sensitive to the correct
wavelengths of light
Occurs in 6% of men and 0.5% of women

33. Testing for Color Blindness
Color Blindness Test

34. Processing Sensory Information
Sensory register – memory system that records information received by receptor cells (stored as a sensory trace)
Specific to each sense
Why need a sensory register?
Size of the sensory register?
Change Blindness Test

35. Dissection of the Cow Eye
Blue Book: Pg
Yellow Book: Pg
Find the structures on your handout
What is the tapetum lucidum?
Do you have a tapetum lucidum?