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visual system
anatomy and physiology visual system
Question | Answer |
---|---|
Name the primary organs of vision | Eye optic nerve Chasm &tract cranial N. 2 thalamus of the brain Primary visual cortex Lateral geniculate nucleus, in the thalamus |
Eye is long | myopia |
Lens is clouding up | cataracts |
Loss of lens elasticity | presbyopia |
Poor drainage of aqueous humor by canal of schlemm | glaucoma |
Eye is short | hyperopia |
Irregular curvature of the lens or cornea | astigmatism |
Symptom of myopia? | Objects appear blurry far away Difficulty seeing close objects |
symptom of cataracts? | Lens is clouding up |
symptom of presbyopia? | Loss of lens elasticity |
symptom of glaucoma? | Poor drainage of aqueous humor by canal of schlemm |
symptom of hyperopia? | Eye is long,farsighted objects are blurry close up |
symptom of astigmatism? | Irregular curvature of the lens or cornea |
Secondary organs of vision | Extra-ocular eye muscles Eyelids conjunctiva, lacrimal apperatus |
Function of the retina | thin layer of tissue lines the back of the inside of the eye , it receives light that the lens has focused converts into neural signals and then sends these signals to the brain for visual recognition. |
optic nerve function | Transfers visual information from the retina to vision centers of the brain, via electrical impulses. |
optic nerve made up of? | ganglionic cells or nerve cells of over one million nerve fibers |
Rods- type 1 of 2 types of photo receptors | *Night vision- light sensitive *can fire in low light only once * Best for peripheral vision * peripheral has majority of rods. * Only one type of rod. +not at the back of eye Front and side only |
Cones- 2nd type of photo receptors | Day vision or color vision Less sensitive to light Best for central vision+very little at sides 3 types of cones: red blue green cones |
What is the visual reflex center called? | Superior colliculus |
Where is there an increase in intra-ocular pressure? what is the pathology? describe | glaucoma |
Where is the primary structure of vision located? | The visual reflex center -superior colliculi |
accommodation reflex | |
Where is the greater amount of cones located? | The macula lutea |