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. Tongue 4 major classes: bitter sour salty sweet Gustation

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. 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 Image Formation

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