Special Senses: VisionThe SensesAccessory Structures of the EyeSlide 4Slide 5Extrinsic Eye MusclesThree Tunics: Sclera/Cornea, Choroid, SensoryNeurons of the Retina (Sensory Tunic)Slide 9Cone SensitivityLens and HumorsLens AccommodationSlide 13Cow EyeImages Formed on the Retina are Upside DownVisual PathwayEye ReflexesSlide 18Special Senses: VisionOverview of Special SensesAnatomy of the Eye•External Anatomy•Internal AnatomyPhotoreceptionLens AnatomyRefraction of Incoming LightTransmission of Visual InformationVisual ReflexesThe SensesGeneral senses of touch•Temperature•Pressure•PainSpecial senses•Smell•Taste•Sight•Hearing•EquilibriumAccessory Structures of the EyeAccessory Structures of the EyeLacrimal apparatus•Lacrimal gland – produces lacrimal fluid•Lacrimal canals – drains lacrimal fluid from eyesFigure 8.1aExtrinsic Eye MusclesFigure 8.2Three Tunics: Sclera/Cornea, Choroid, SensoryFigure 8.3aNeurons of the Retina (Sensory Tunic)Figure 8.4Retinal AnatomyCone SensitivityThere are three types of conesDifferent cones are sensitive to different wavelengthsColor blindness is the result of lack of one cone typeFigure 8.6Cones “see” in colorRods “see” in shades of grayLens and HumorsFigure 8.3aLens AccommodationFigure 8.9Light must be focused to a point on the retina for optimal visionThe eye is set for distance vision (over 20 ft away)The lens must change shape to focus for closer objects Lens flattened (ciliary muscle relaxation) for distance vision Lens bulges (ciliary muscle contraction) for close-up visionProblems in Lens Accommodation: Nearsighted and FarsightednessCow EyeaqueoushumorOptic nerveBlind spot/optic discImages Formed on the Retina are Upside DownFigure 8.10Visual PathwayFigure 8.11Eye ReflexesInternal muscles are controlled by the autonomic nervous system•Bright light causes pupils to constrict through action of radial and ciliary muscles•Viewing close objects causes accommodationExternal muscles control eye movement to follow objectsViewing close objects causes convergence (eyes moving medially)Special Senses: VisionOverview of Special SensesAnatomy of the Eye•External Anatomy•Internal AnatomyPhotoreceptionLens AnatomyRefraction of Incoming LightTransmission of Visual InformationVisual
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