Anatomy of the Eye Mr. Young Anatomy & Physiology

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Anatomy of the Eye

Anatomy of the EyeMr. YoungAnatomy & Physiology

YOUR EYES . . .70% of ALL SENSORY RECEPTORS in the body1,000,000 nerve fibers per eyemore than 2 million working partsaverage person blinks 12 times per minute - about 10,000 blinks in an average daycan distinguish 500 shades of the gray.contribute towards 85% of your total knowledge.always the same size from birth

EyelidsConjunctivaLacrimal apparatusAccessory StructuresSECRETIONS:

Sebum (oil): tarsal glands

Mucus: conjunctiva

Tears: lacrimal glandAntibodiesLysozymes

Accessory StructuresExtrinsic muscles

What do you know?

Know the Three TunicsThe Fibrous TunicScleraWhite connective tissue layerSeen anteriorly as the white of the eyeCorneaTransparent, central anterior portionAllows for light to pass throughRepairs itself easilyThe only human tissue that can be transplanted without fear of rejectionChoroid LayerBlood-rich nutritive tunicPigment prevents light from scatteringModified interiorly into two structuresCilliary body smooth muscleIrisPigmented layer that gives eye colorPupil rounded opening in the irisSensory Tunic (Retina)Contains receptor cells (photoreceptors)RodsConesSignals pass from photoreceptors via a two-neuron chainBipolar neuronsGanglion cellsSignals leave the retina toward the brain through the optic nerve

Neurons of the Retina and VisionRodsMost are found towards the edges of the retinaAllow dim light vision and peripheral visionPerception is all in gray tonesNeurons of the Retina and VisionConesAllow for detailed color visionDensest in the center of the retinaFovea centralis area of the retina with only conesNo photoreceptor cells are at the optic disk, or blind spotCone SensitivityThere are three types of conesDifferent cones are sensitive to different wavelengthsColor blindness is the result of lack of one cone typeFigure 8.6

Blind Spot

What about non-visual light perception?Video 1Video 2Cataract

AstigmatismUnequal curvatures in lens/cornea

The Result of a Biconvex Lens

Now . . .. . . a few tests to reinforce the role of the brain in vision.

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