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The eye parts
| description | function |
|---|---|
| 1.Sclera | -outermost coat of the eyeball -tough, fibrous and opaque -protects the eye from physical injury -maintains the shape of the eyeball |
| 2. Cornea | - a transparent layer continuous with the sclera -light enters the eye through the cornea -refracts the light rays that enter the eye |
| 3. Conjunctiva | -a transparent membrane that covers the exposed part of the eyeball -protects the cornea |
| 4. Choroid | -the middle coat of the eyeball -contains a black pigment and has a network of blood capillaries -black pigment absorbs light and prevents the internal reflection of light -blood vessels supply oxygen and nutrients to the cells of the retina |
| 5. Ciliary body | -a thickened region at the front end end of the choroid -changes the thickness of the lens during accommodation |
| 6. Iris | -a circular sheet muscles -circular muscles and radial muscles -contains pigments / give / colour -changes pupil size/ through the antagonistic action /circular and radial muscles, thereby adjusting the amount of light that enters the eye |
| 7. Pupil | - a round opening in the iris -allows light to enter |
| 8. Retina -innermost layer of the eyeball | -consists /two types of photoreceptor cells: cone cells and rod cells -act as a screen/the formation of images -rod cells / sensitive to low light /responsible /vision night/cone cells /responsible / color vision /high light intensity |
| 9.Fovea (yellow spot) | -situated in line /optical axis of the lens -contains only cone cells/ most photosensitive area of the retina -where images are normally focused -provide the clearest vision |
| 10. Blind spot | -the area/neurones leave the retina/form optic nerve -does not contain any photoreceptors -has no photoreceptors, not sensitive to light(no vision /image falls on it) |
| 11. Lens | -flexible biconvex crystalline structure behind the iris -divides the eye /2 chambers/ AC and VC -curvature/focal length changed/focus on near or far objects -refracts light rays onto retina |
| 12.Aqueous humour | -a clear watery fluid in AC -maintains the internal pressure of the eye -provides nutrients for the lens and cornea -refracts light rays |
| 13.Vitreous humour | -jelly-like substance in the vitreous chamber -maintains the shape of the eye -prevents collapse of the eye -refracts light rays |
| 14. Suspensory ligament | -attaches the lens to the ciliary body --holds the lens vertically in the eye -assists the lens to change its thickness during accommodation |
| 15. optic nerve | - a nerve in the eyeball - transmits nerve impulses from the retina to the brain |
Created by:
NoraNyein
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