1. EYES AND EARS

2. GENERAL DESCRIPTION Eyes: visual organ
Ears: the organ of hearing and equilibrium.
The equilibrium sense, generally associated with balance, provides feedback about the positions and movements of our heads and bodies in space.

3. OBJECTIVES Know the general layers of the eye.
Describe the structure of Cornea and its reason of transparent.
Describe the structure of Retina and the function of pigment cell, rod cell and cone cell.
Know the definition of Ora serrata, Macula lutea, Fovea centralis and Optic disc.
Know the general structure of ear.
Describe six sensory regions of the membranous labyrinth and their function.

4. THE EYE

5. eye Fibrous layer Walls Vascular layer eyeball Retina
Content：Aqueous humor、Lens、
Vitreous body
Accesory structure:Eyelid、Muscles of the eye、Lacrimal gland

6. Ciliary body Eyeball Walls Cornea 1/6 Fibrous layers Sclera 5/6
Eye ball Vascular layers
Retina
Sclera 5/6
Choroid 2/3
Ciliary body
Iris

7. Cornea Colorless, transparent 5 layers: epithelium Bowman’s membrane
Stroma
Descemet’s membrane
endothelium

8. Cornea keratin a.epithelium:
Non-keratinized stratified squamous epi.
5-6 layers
Numerous mitotic figures
No vessels.
Free nerve ending
b.Bowman’s membrane( anterior basement membrane)
An accellular homogeneous membrane
(collagen fibrils)
Stability & strength, no regeneration

9. C. Stroma or substantia propria
Several lamellae of fine collagen f.network
Flattened fibroblasts
G.S.rich in chrodroitin sulfate
D. Descemet’s membrane (posterior limiting lamina)
Acellular homogeneous membrane
Can be repaired by endothelial cells
E.Endothelium
Like mesothelium in its morphology
Regulate the water content of the stroma  maintain transparency

10. 胶原板层电镜图
相邻胶原板层的纤维方向垂直
胶原板层纵断面
胶原板层横断面

11. 胶原板层结构
lamellae of fine collagen f.network
fibroblasts

12. The reasons of cornea transparent
No blood vessels & pigments
Basal of epi. is plane
Uniform spacing of collagen fibrils and lamellae in stroma
G.S. with transparent nature & maintains proper water

13. Retina Two regions: The nonphotosensitive region (nonvisual part)
Located anterior to the ora serrata, no photoreceptors.
The photosensitive region (optic part)
Lines the inner surface of the eye posterior to the ora serrata (except the optic papilla)

14. Retina 4 layers of cells: Pigment cells Optic cells Bipollar cells
Ganglion cells

15. Pigment epithelium Structure：
1) Simple cuboidal epi. Attached to choroid and easy separated from retina (detachment of retina)
2) Junctional complex ,
3) Melanin granules
4) Processes (contain pigment granules)
Function：
absorb light,protect rod and cone from strong light
Blood-retina barrier
3) Phagocytize the membranous discs from retinal photoreceptor cells
4) Store vitamin A to assist in forming rhodopsin

16. Optical cells bipolar neurons The rods and cones
Glial cells（Müller cell）

17. Rod cell Thin,elongated cells， about 120 million rods
A body and two opposite processes
Outer segment and inner segment
separated discs ,shed disc phagocytized by pigment cells
rhodopsin (visual purple)
Function:
sensitive to low intensity light
Night vision (lack of vitamin A leads night blindness)

18. cone cell About 7 million cells
Located in posterior part of retina,especially in fovea
Outer and inner segments (conical)
Continuous discs & not renewed
Function
1）sensitive to high intensity light
2）color distinguishing（red、blue、green iodopsin）
(photoactive substance)

19. Bipolar cells An axon & a dendrite Synapse with photoreceptor
cells and ganglion cells
Müller cells
Extend entire thickness of retina
Neuroglia
Horizontal cells
Amacrine cells

20. Ganglion cells The dendrite synapse with bipolar cells
The axons concentrate together form optic nerve

21. Specilized regions of the retina
Ora serrata ：neural layer ends anteriorly at ciliary body,pigment cells extend to cover posterior iris
Macula lutea:directly on eye’s posterior pole. “yellow spot”,mostly cones
Fovea centralis: central pit of macula,only cones, vision acuity straight on
Optic disc:blind spot,no rods or cones,optic nerve exits,medial and inferior to fovea centralis.

22. 10 layers 1 = pigmented epithelium 2 = layer of photoreceptors
3 = external limiting membrane
4 = outer nuclear layer
5 = outer plexiform layer, where photoreceptors synapse
6 = inner nuclear layer of bipolar neurons
7 = inner plexiform layer, where bipolar neurons synapse with ganglion cells
8 = ganglion cell layer
9 = optic nerve layer
10 = internal limiting membrane

23. Visual pathways light cornea champer lens vitreous body retina
pigment epithelium rods and cones bipolar cells ganglion cells optic nerve fibers

24. Ear External, middle, inner ear External and middle ear:
gathers and funnels sound waves
Inner ear:
sensory of hearing and balance

25. (auricle) External ear ： auricle Middle ear： Mastoid process
external acoustic meatus
tympanic membrane
Middle ear：
tympanic cavity
auditory tube
mastoid process

26. Internal ear Bony labyrinth
Membranous labyrinth
Bony labyrinth：
Semicircular canals
Vestibule
Cochlea
Menbranous labyrinth：
Cochlear labyrinth
Vestibular labyrinth
three semicircular ducts
Utricle and saccule

27. Six sensory regions of the membranous labyrinth:
Three crista ampullaris
Two maculae(maculae of utricle, maculae of saccule)
The spiral organ of Corti

29. Crita ampullaris
three，located in the membranous ampullae of the semicircular ducts
Composition：
Supporting cells：support，forming cupula
Sensory hair cells：with stereocilia and kinocilium are embedded in the cupula
Function：
sensors of angular acceleration of the head

31. 壶腹嵴 de 功能
感受旋转运动

32. Maculae of utricle and saccule：
Located in the vestibule
Sense the position of the head and its linear movement

33. 前庭的毛细胞

34. 位觉斑 de 功能
直线运动开始和终止、头部静止的位觉。

35. Note：
The position of cochlear duct within the turns of the bony cochlea
The scala vestibuli and the scala tympani, containing perilymph
The scala media containing endolymph

36. Schematic diagram of the cochlea:
Scala vestibuli
Scala tympani

37. Corti’s organ：sensor of sound vibration
On the lower wall of the scala media
Tectorial membrane
Inner (close to spiral lamina)and outer (farther from the spiral lamina) hair cells
Supporting cells: inner and outer phalangeal cells
pillar cells

39. Sounds Pathawy
Sound comes
Hits tympanic membrane to vibrate
three auditory ossicles vibrate
vibration at tympanic (oval) window
Vibration in the perilymph of the scala vestibular to the scala media
Vibrates of basilar membrane and tectorial membrane,and hair cells attached to also vibrates
Vibrate the stereocilia of the hair cells and initiate neuronal transduction

40. Clinical Correlation Vertigo: dysfunction of vestibular system
Causes: viral infections, certain drugs, tumors, excessive stimulation (seasickness, carsickness, or airsickness)
Hearing loss
1)Conductive hearing loss: sound waves are mechanically impeded from reaching the auditory sensory receptors within the internal ear.such as excessive accumulation of cerumen.
2)Sensorineural hearing impairment: injury to the auditory hair cells or the cochlea nerve. May be congenital or acquired. Causes include infections, trauma (exposure to excessive noise), administration of certain antibiotics, aging.

41. Thanks for your attention