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Histology 17

NSU

Spring 2009

Taken by: Gregory Rodocker

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Photoreceptor and

Audioreceptor Systems

The Eye Complex, highly developed

photosensitive organ Form

Light intensity

Color

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External Layer: Tunica fibrosa

Sclera Tough, white opaque layer of dense CT

with few fibroblasts on five sixths of theeyeball exterior

Cornea Colorless, transparent multilayered

structure that allows light to enter

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Middle or Vascular Layer

Actually contains the following

structures: Choroid Ciliary body

Iris

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Choroid

Highly vascularized loose CT filled

layer containing fibroblasts,

macrophages, lymphocytes, mastcells, plasma cells, collagen fibers and

elastic fibers

Melanocytes also present giving thelayer its characteristic black coloration

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Ciliary body

Anterior extension of the choroid

Contains several sets of muscles that

function in visual accommodation

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Ciliary processes

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Ciliary processes

Loose CT core

Fenestrated capillaries

Produces the aqueous humor Similar to plasma but with 0.1 % protein

compared to 7% in plasma

Travel through pupil to anterior chamberand drains via canal of Schlemm

Anchors lens in place via zonular

fibers

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Iris

Extension of choroid

Contains the round opening called the

pupil

Loose CT, Fibroblasts and

melanocytes

Dilator and sphincter pupillae muscles

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Lens

Lens capsule

Subcapsular Epithelium

Lens fibers

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Accommodation

Lens is stretched when looking at

distant objects by elasticity of ciliary

body To focus closer in, the ciliary muscles

contract; zonular fiber tension is

relieved and the lens thickens

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Retina

Innermost layer of the eye

Posterior photosensitive portion and

Anterior part covering ciliary body and

iris

Layers of photosensitive portion Pigmented epithelium

Neural portion

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The Ear

Internal Ear

Membranous labyrinth Cochlea

Utricle

Saccule

Semicircular canals

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Receptor hair cells

Each has 40-80

rigid stereocilia

(microvilli) and onecilium (kinocilium)

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