1. Special Senses: Olfaction, Taste and Vision Pp. 264-293 in the lab book

2. Types of Sensory Receptors I.Chemoreceptors – detect chemical cues Ex: taste and smell II.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 in the air.

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 Bud Taste Cells

8. Taste Activities Locate the papillae on your tongue – Pg. 290 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 5 th “taste” Umami is the distinctive taste found in meat and cheese Led to the creation of MSG as a seasoning/preservative

10. Do Activity 4: 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 5: The effect of smell on taste Fill out the table on Pg. 292

12. Hearing Inner Ear Outer Ear Middle Ear

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

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

16. Ear Infection (Otis 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. pupil

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

19. 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

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

23. The Causes of Near/Far Sightedness 1.Lens over or under compensates when focusing 2.Eyeball is too long or too short for proper focusing 3.Cornea or lens has improper curvature

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

26. Glaucoma Vitreous humor is constantly being created and draining from the eye Blockage stops drainage, putting pressure on the retina & optic nerve

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

29. Testing for Astigmatism Do Activity 9: Testing for Astigmatism

30. Color Blindness Normal VisionColor Blind

31. 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

32. Testing for Color Blindness Color Blindness Test

33. Dissection of the Cow Eye – Pg. 270-271 Find the parts listed in your handout What is the tapetum lucidum? Do you have a tapetum lucidum?