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Eye - Coggle Diagram
Eye
fibrous tunic 
cornea
5 layers, 3 need to know
Corneal stroma (substantia propria) - very thick, composed of thick bundles of collagen fibers (Type I and II) arranged in layers/lamellae. The stroma is highly innervated but avascular. The ground substance contains proteoglycans and glycosaminoglycans (GAGs) which are important in maintaining corneal hydration. The highly organized arrangement of collagen fibers allows the cornea to be transparent.
is a single layer of squamous cells. These cells help maintain corneal hydration. Damage can result in corneal swelling and loss of transparency. This layer is not capable of repair in adults.
Corneal epithelium - nonkeratinized stratified squamous epithelium which contains many naked nerve endings
limbus
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area where the fluid in the anterior chamber, aqueous humor, flows out- filtration angle or iridocorneal angle
sclera
composed of dense irregular connective tissue with generous amounts of elastic fibers and glycosaminoglycans
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vascular tunic
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choroid: between retina and sclera
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Tapetum lucidum (tapetum) - a cellular or fibrous layer positioned between the choriocapillary layer and the more external large blood vessels
When a tapetum is present, it lies beneath nonpigmented pigmented epithelium of the retina. This is compared to a nontapetal area where pigmented epithelium of the retina IS pigmented.
Bruch's membrane (basal complex) - the basement membrane that separates the choriocapillary layer from the pigmented epithelium of the retina
Vessel layer- loose connective tissue, melanocytes, medium and large veins, and a few large arteries
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lens: separates the posterior chamber from the vitreous humor
lens epithelium: cuboidal epithelium on the anterior surface of the lens. The lens epithelium has a germinal zone at the equator of the lens which produce lens fibers.
Lens fibers - the cells from the germinal zone elongate and change into lens fibers. Initially, the nuclei remains in the center of the cell while elongation occur. This creates a characteristic lens bow due to the difference in length of younger and older lens fibers. As the cells mature, they move towards the center of the lens and lose their nuclei to appear as lens fibers.
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lens capsule: a thick basement membrane with fine reticular fibers that completely encases the lens
ocular adnexa
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palpebrae
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The palpebral conjunctiva is initially a nonkeratinized stratified squamous epithelium (mucous membrane) which transitions to a pseudostratified columnar epithelium with many goblet cells
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nictitating membrane (third eyelid): covered by conjunctiva, core of hyaline or elastic cartilage, lymphatic nodules, glands of the third eyelid
nervous tunic (retina)
Neural Retina - lies on the side toward the vitreous body. It contains photoreceptor cells and is divided into 9 layers. This layer is only found in the optic (photosensitive) part of the retina.
Retinal pigmented epithelium - single layer of pigmented (in most regions) cuboidal cells that rest on the vascular tunic. This layer is continuous across the iridial, ciliary and optic parts.
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