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special senses 1632736664492 - Coggle Diagram
special senses 
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Vision( The Eye)This is the organ of sight, situated in the orbital cavity and supplied by the optic nerve ( 2nd cranial nerve)
Structure ( When Michael entered a dark room the following are the structures enabled him to see in darkness)
1.Sclera - this is the outer fibrous layer.Light first enters the eye through this layer.It is a fibrous membrane that maintains the shape of the eye and gives attachment to the extrinsic muscles of the eye.
Pupil-this is the black circle in the center of the Iris. its size contributes to clear vision by controlling the amount of light entering the eye.When Michael got into a dark room , his iris widened and pupils dilated to allow more light to come through
The Lens- light from the Iris hits the lens.This is the clear structure inside the eye that focuses the light rays onto the retina
Vitreous humor- This is the clear, jelly likesubstance that fills the center of the eye.It helps keep the eye round in shape
Retina- innermost lining of the eye, composed of nerve cell bodies and their axons. This is the light sensitive nerve layer that lines the back of the eye.Light rays from the retina are converted into nerve impulses.
rods
specialized neurons that convert visual stimuli in the form of photons into chemical and electrical stimuli that can be processed by the CNS
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Optic nerves( second cranial nerve)The fibres of the optic nerve originate in the retina and converge to form the optic nerve about 0.5cm to the nasal side of the macula lutea at the optic disc.This nerve is responsible for carrying signals to the visual cortex of the brain.The visual cortex turns the signals into images enabling Michael to see in the dark .
Rhodopsins
family of light sensitive pigments,which are broken down when they absorb light hitting cell.When Michael moved into the dark room, light intesity was not enough to stimulate the rods causing temporal vision impairment while the rhodopsin was being generated within the rods.
2.Cornea- Continuation of the sclera,it has a clear transparent membrane.Light rays pass through the cornea from the sclera to the retina.Its convex shape allows it to direct light to the retina
3.Choroid- this is very rich in blood vessels and is deep chocolate brown in colour .Light enters the eye
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