structure and function of eye
DESCRIPTION
eye, external and internal structure, brief structure of eye partsTRANSCRIPT
![Page 1: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/1.jpg)
STRUCTURE & FUNCTION OF EYE
![Page 2: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/2.jpg)
INTRODUCTION
Gift of the CreatorGives us the sense of sight70% of all sensory receptors are
in the eyeSpheroid structure, about 2/3 the
size of a ping-pong ballFunctions: distinguishes light and
dark, shape, colour, brightness & distance of objects.
![Page 3: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/3.jpg)
EXTERNAL STRUCTURE OF EYE
Includes : bony orbit, eyelids, eyelashes, tears and fat glands, extra ocular muscles, conjunctiva
![Page 4: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/4.jpg)
BONY ORBIT/EYE SOCKET
Most of the eye is enclosed in a bony orbit
Structure:o Cheekboneo Foreheado Templeo Side of noseFunction:Provides protection to the eye
![Page 5: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/5.jpg)
EYELIDS
A thin fold of skin that covers the eye Protect eye from foreign matter (dust, dirt,
debris) Protect against bright light that might
damage the eye Lubricate the eye surface by distributing
tears over the corneaUpper eyelid
Lower eyelid
![Page 6: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/6.jpg)
EYELASHES
Are the hairs that grow at the edge of eyelidsProtect the eye by filtering out foreign matter
![Page 7: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/7.jpg)
CONJUNCTIVA
A thin, clear layer of skin Lines the inner surface of eyelids & covers the front surface of the eyeball except the cornea Secretes mucus to lubricate the eye Keeps bacteria and foreignmaterial from getting behind eye
![Page 8: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/8.jpg)
INNER LAYER
![Page 9: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/9.jpg)
STRUCTURE OF RETINA
Innermost, sensitive layer of the eye
A delicate membrane containing photoreceptors & associated neurons
![Page 10: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/10.jpg)
PHOTORECEPTORS
Are of two main kinds:RodsCones
![Page 11: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/11.jpg)
RODS
Sensitive to dim lightPresent everywhere in the retina except the foveaAllow dim light vision & peripheral vision125 million rods in the average retina
![Page 12: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/12.jpg)
CONES
Sensitive to bright lightClustered near the centre of retina(fovea)Distinguish colours & allowsharp vision5 million cones in the average retina
![Page 13: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/13.jpg)
FOVEA
A depression in the retina directly opposite to lens
![Page 14: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/14.jpg)
Fovea (cont.)
Contains only cones & no rods
Function: to form an extremely clear image
Is directed towards whatever object you are studying most closely
![Page 15: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/15.jpg)
OPTIC DISC/BLIND SPOT
A point where the optic nerve enters retina
Optic disc
Optic nerve
![Page 16: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/16.jpg)
BLIND SPOT
absence of cones & rods at the optic discNo vision is possible hereReferred to as blind spot
![Page 17: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/17.jpg)
OPTIC NERVE
The bundle of over one billion nerve fibres that carry visual messages from the retina to the brain.
![Page 18: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/18.jpg)
![Page 19: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/19.jpg)
RETINAL BLOOD VESSELS
Arteries transmit oxygen & nutrients
Veins carry deoxygenated blood from the eye
![Page 20: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/20.jpg)
FUNCTION OF RETINA
Transforms light energy to electrical signals
![Page 21: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/21.jpg)
CHAMBERS OF EYE
Anterior Chamber
Posterior Chamber
![Page 22: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/22.jpg)
AQUEOUS HUMOUR
A clear, watery fluid in the anterior chamber
Nourishes the lens & cornea and helps refract light onto the retina
![Page 23: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/23.jpg)
VITREOUS HUMOUR
A clear, gel-like fluid in the posterior chamber
Supports the lens & retina and keeps the eye from collapsing
Aids the magnifying power of the eye
![Page 24: Structure and function of eye](https://reader033.vdocuments.net/reader033/viewer/2022061204/547eaa8db4af9fc9158b56ee/html5/thumbnails/24.jpg)
WORKING OF THE EYE
Light rays coming from object enter through the cornea, progress through pupil & fall on eye lens which converts light rays & produces a real & inverted image of object on retina. The image thus formed is conveyed to brain by optic nerve in the form of electrical signals which are seen by the brain as a visual image.