1. Special Senses
Chapter 17

2. The Special Senses Smell, taste, vision, hearing and equilibrium
Housed in complex sensory organs
Ophthalmology is science of the eye
Otolaryngology is science of the ear

3. Olfactory Epithelium and Receptors

4. Physiology of Olfaction
Many different combinations of receptors produces the possibility for thousands of different odor sensations.
Low threshold, only few molecules needed.
Adaptation - rapid

5. Physiology of Olfaction

6. Olfactory Pathway Olfactory receptors Olfactory (I) nerves
Olfactory tract
Temporal lobe (primary olfactory area)

7. Gustation
Tongue
4 major classes:
bitter
sour
salty
sweet

8. Anatomy of Taste Buds and Papillae
Taste bud- made of three types of epithelial cells: supporting cells, gustatory receptor cells and basal cells.
About 50 gustatory cells per taste bud. Each one has a gustatory hair that projects through the taste pore.
Taste buds are found in the papillae.
Three types of papillae: vallate (circumvallate), fungiform and foliate.

9. Physiology of Gustation
Five types of taste: sour, sweet, bitter, salty and umami.
Tastant dissolves in saliva → plasma membrane of gustatory hair→ receptor potential→ nerve impulse via cranial nerves VII, IX and X→ medulla→ thalamus→ primary gustatory area of the cerebral cortex.

10. Vision

11. Accessory Structures of Eye

12. Lacrimal Apparatus

13. Anatomy of Eye

14. Wall of the Eyeball Three layers: Fibrous tunic- outer layer
Sclera “white” of the eye
Cornea-transparent coat
Vascular tunic or uvea- middle layer
Choroid
Ciliary body consists of ciliary processes and ciliary muscle
Iris
Retina- inner layer
Optic disc
Macula lutea- fovea centralis

15. Muscles of Iris

16. Retina
View with Ophthalmoscope

17. Retina

18. Interior of the Eyeball
Lens
lack blood vessels, consists of a capsule with proteins (crystallins) in layers; transparent.
divides the eyeball into two cavities: anterior and posterior.
- Anterior cavity- further divided into anterior and posterior chambers. Both are filled with aqueous humor.
- Posterior cavity (vitreous chamber)-filled with vitreous body.

19. Chambers of the Eye

20. Cavities of the Interior of Eyeball
Anterior cavity (anterior to lens)
filled with aqueous humor
produced by ciliary body
continually drained
replaced every 90 minutes
2 chambers
anterior chamber between cornea and iris
posterior chamber between iris and lens
Posterior cavity (posterior to lens)
filled with vitreous body (jellylike)
formed once during embryonic life
floaters are debris in vitreous

21. Eye Structure Summary

22. Image Formation
Refraction: Bending of light as it passes from one substance (air) into a 2nd substance with a different density (cornea)
In the eye, light is refracted by the anterior & posterior surfaces of the cornea and the lens

23. Vision Correction

24. Photoreceptors
Rods
Cones

25. Photopigments

26. Neurotransmitters of Vision

27. Visual Pathway

28. Anatomy of Ear

29. Middle Ear

30. Inner Ear

31. Cochlea and Cranial Nerve VIII

32. One Turn of Cochlea and Organ of Corti

33. Physiology of Hearing

34. Auditory Pathway

35. Balance and Position

36. Crista and Rotational Movement

37. Ear Structure Summary