Exam #3 Study Guide

Exam #3 Study Guide - Exam#3 Study Guide CHAPTER 3 o Vision...

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Exam #3 Study Guide CHAPTER 3 o Vision Each eye is once inch in diameter Vision Problems Myopia o Far items blurred o Lens focusing image too far forward Hyperopia o Near items blurry o Lens focuses image too far back o Parts Of Eye Cornea Tough, transparent, protective layer covering the front of the eye Performs the first step in vision by bending light rays inward o Directs light rays through the pupil and contracts the pupil to regulate the amount of light entering the eye Lens Suspended just behind the iris and the pupil Composed of many thin layers and looks like a transparent disc Focuses on viewed objects Focuses the light Flattens as it focuses on objects at a distance and becomes more spherical bulging in center as is it focuses on closes items Pupil
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Iris (muscle) regulates opening o Color part of eye Dim=pupil open wider Bright=constrict Retina Back of eyeball Contains 2 kinds of cells o 1. Rods Low illumination levels: forest at night Extremely sensitive, allowing the eye to respond to as few as five photons of light 120 million Slender cylinders o 2. Cones Bright light, color, detail Receptor cells that enable us to see color and fine detail in adequate light, but DO NOT function in very dim light In center of retina 6 million Short and round Image on retina is flipped and upside down Adaption Dark o Adapt to low levels of light o 100,000x more sensitive to light in 30 minutes in the light o Changes in chemicals found in rods
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Rhodopsin Enables us to adapt to variations in light Vitamin A deficiency can lead to night blindness Light o Stumble out of the theatre may be temporarily blinded o Short period of readjustment Fovea Center of retina Only cones in fovea, no rods Region of maximum visual acuity o Provides clearest and sharpest area of vision in whole retina Blind Spots Another name for optic disk is Blind spot Sensory receptors translate light into neural impulses; connect w/ bipolar cells, then ganglion cells. Axons are bundled together and leave retina at optic disk (Blind Spots) Optic Nerve Occipital lobe is involved w/ vision o Damage to one will result in partial vision in each eye Optic nerve carries impulses from the retina to the brain Fibers cross ate the optic chiasm, go to the thalamus and then primary visual cortex Some cells are specialized Optic Chiasm o A point where some of the nerve fibers cross to the opposite side of brain
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o Right retina goes to right hemisphere and left retina go to left hemisphere Crossing is important b/c it allows visual information from a single eye to be represented in primary visual cortex of both hemispheres of brain o Properties of Light Hue= color Determined by wavelength Brightness=intensity Amplitude of waves vary o Pink w/ low waves Saturation=Purity Unsaturated=mixed
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Exam #3 Study Guide - Exam#3 Study Guide CHAPTER 3 o Vision...

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