Visual sense
Transcript of Visual sense
Visual Sense (pg 10)
Layers of the eyeball
Layers of the eyeball• Fibrous tunic: Outer coat. Consists of cornea
(clear) and sclera (white)
Layers of the eyeball• Fibrous tunic: Outer coat. Consists of cornea
(clear) and sclera (white)• Vascular tunic: Middle layer. Contains many
blood vessels. Consists of choroid (dark brown layer that absorbs excess light) and iris (colored part of the eye. Doughnut shaped. Has muscles that constrict or dilate the iris to change the size of the pupil)
Layers of the eyeball• Fibrous tunic: Outer coat. Consists of cornea
(clear) and sclera (white)• Vascular tunic: Middle layer. Contains many
blood vessels. Consists of choroid (dark brown layer that absorbs excess light) and iris (colored part of the eye. Doughnut shaped. Has muscles that constrict or dilate the iris to change the size of the pupil)
• Retina: Inner layer. Lines the posterior ¾ of the eyeball. Contains photoreceptors
Interior of the Eyeball• Lens: transparent, convex structure that
focuses light onto the retina
Interior of the Eyeball• Lens: transparent, convex structure that
focuses light onto the retina• Ciliary muscle: Alters the shape of the lens for
viewing objects up close or at a distance
Interior of the Eyeball• Lens: transparent, convex structure that
focuses light onto the retina• Ciliary muscle: Alters the shape of the lens for
viewing objects up close or at a distance• Anterior cavity: space anterior to the lens.
Filled with aqueous humor (watery)
Interior of the Eyeball• Lens: transparent, convex structure that
focuses light onto the retina• Ciliary muscle: Alters the shape of the lens for
viewing objects up close or at a distance• Anterior cavity: space anterior to the lens.
Filled with aqueous humor (watery)• Vitreous chamber: large cavity behind the
lens. Filled with vitreous humor (jelly-like)
Photoreceptors
• Rods: 120 million. Sensitive to dim light. Only see black and white. Most abundant at edges of retina
Photoreceptors
• Rods: 120 million. Sensitive to dim light. Only see black and white. Most abundant at edges of retina.
• Cones: 6 million. 3 types: blue, green, and red. Stimulated by brighter light. Allows color vision. Most abundant at the fovea centralis, a point at the center of the retina where images are sharpest
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• Hold up “rod” or “cone” sign
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1. Responsible for peripheral vision
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1. Responsible for peripheral vision
RODS
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2. Used in moonlight
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2. Used in moonlight
RODS
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3. Missing in color-blind people
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3. Missing in color-blind people
CONES
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4. If these are damaged you should not drive at night
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4. If these are damaged you should not drive at night
RODS
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5. Allows you to see fine detail
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5. Allows you to see fine detail
CONES