Eye The eye is a photosensitive organ located in the orbits. It can capture and focus the light and film to record the image from the objects
Structure of eye The wall of eyeball: external layer— sclera,cornea middle layer— choroids,ciliary body,iris inner layer— retina Internal structures: lens vitreous body aqueous humor
Anterior chamber Posterior chamber zonule
Vitreous space
External layer Sclera: The posterior fivesixthes,opaque Cornea: The anterior onesixth; colorless and transparent; like a round discLimbus
Cornea 1. Corneal epithelium 2. Bowman’s membrane /Anterior limiting lamina 3. Corneal stroma 4. Descemet’s membrane /Posterior limiting lamina 5. Cornea endothelium
Corneal epithelium composed of nonkeratinized stratified squamous epithelium no melanocyte smooth base covered with tear film Rich in nerve endings
Bowman’s membrane A fibrillar lamina composed of numerous collagen fibers No cells Function
Corneal stroma Dense regular collegenous connective tissue with fibroblast
Descemet’s membrane & Corneal endothelium Descemet’s membrane—basal lamina of the endothelium Corneal endothelium—a simple squamous epithelium
cornea
Corneal limbus Schelmm’s canal /Sinus venous sclera Trabecular meshwork Scleral spur
sclera
Middle layer Choroid The posterior two thirds
Ciliary body A thickened anteior portion
Iris The most anterior portion
Choroid
composed of loose connective tissue blood vessels melanocytes
choroid
Ciliary body 1.Ciliary muscles: smooth muscles in three directions 2.Ciliary stroma: Loose connective tissue 3.Ciliary epithelium: anterior pigmented layer Posterior unpigmented
Ciliary process
Ciliary epithelium
Iris
Iris 1.Anterior border layer: Composed of melanocytes, fibroblasts and collagen fibrils 2.Iris stroma: Loose connective tissue 3.Iris epithelium: Anterior smooth muscle Posterior epithelium
Anterior border layer
Iris stroma
Sphincter muscle of pupil Dilator muscle of pupil
Posterior Iris epithelium
lens
Inner layer (Retina) Nonphotosensitive portion: The epithelium of the ciliary body and iris.
Photosensitive portion: Pigment epithelium Neural retina
Photosensitive Retina
Pigment epithelium Neural retina
Pigment epithelium
A single layer of cuboidal cells with long slender processes
Pigment epithelial cell (EM) Many cell processes Abundant organelles Mitochondria, rER, Golgi complex,Lysosome Melanin granules
Pigment epithelium Functions: 1.absorption of light 2.separation of retina cells from blood substances 3.participation in the restoration of photosensitive substance 4.phagocytosis of segments
Neural retina (cell types) 1-Photoreceptors: Rod cells, cone cells. 2-Conducting neurons: . Bipolar cells, ganglion cells 3-Association neurons: Horizontal cells, amacrine cells .. 4-Supporting cells: Muller cell
Rod cell A thin elongated neuron Most disks are not continous with plasma membrane Sense of weak light vitA
rhodopsin
Outer segment (membranous disk) Inner segment (organelles) Nuclear region Synaptic region
Cone cell
A thin elongated neuron The disks are continous with plasma membrane, attached with iodopsin. Sense of intensive light and color of light
rod cell
cone cell
1. Morphologic structure: Outer segment
Rod-shaped
cone-shaped
Membranous disc
Free from the plasmembrane
Not free
2. Function:
Low level of light
3. relative diseases
Light of a higher intensity and colour
Achromatopsia: Nyctalopia
Protanopia,deuteranopia
Bipolar cell
Interneurons connecting photoreceptors to ganglion cells Diffuse bipolar cells Monosynaptic bipolar cells
Ganglion cells
Typical neurons with axons to form optic nerve Diffuse ganglion cells Monosynaptic ganglion cells
Papilla of optic nerve
Muller cell
Internal limiting membrane
External limiting membrane
Layers of retina 1. Pigment epithelium 2. Layers of rods and cones 3. External limiting membrane 4. Outer nuclear layer 5. Outer plexiform layer 6. Inner nuclear layer 7. Inner plexiform layer 8. Ganglion cell layer 9. Layer of optical fibers 10. Internal limiting membrane
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Layers of retina 1. Pigment epithelium 2. Layers of rods and cones 3. External limiting 4. Outer nuclear layer 5. Outer plexiform layer 6. Inner nuclear layer 7. Inner plexiform layer 8. Ganglion cell layer 9. Layer of optical fibers 10. Internal limiting
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4
1
Central fovea Central fovea Ganglion cell Bipolar cell Visual cell
Optic disk
Structure of eye The wall of eyeball: external layer— sclera,cornea middle layer— choroids,ciliary body,iris inner layer— retina Internal structures: lens vitreous body aqueous humor
Lens 1.Lens capslule: composed of collagen and glycoprotein 2.Subcapsular epithelium: a cuboidal layer of cells 3.Lens fibers: thin flattened structures filled with crystallins
The structure of lens Subcapsule epithelium Lens capsule
Equator of lens Disease: Presbyopia cataract
Lens fibers Nuclear of lens
Vitreous body
Composed of transparent gel Water,collagen, hyaluronic acid hyalocytes
Aqueous humor origin 1.Capillaries of ciliary body 2.the cells of nonpigmented layer of ciliary body
Posterior chamber
anterior chamber small vein
disease: glaucoma
trabecular meshwork
schlemm’s canal
Eyelid movable folds of tissue that serve to protect the eye
Eyelid 1. 1 Skin: thin, keratinized stratified squamous epithelium
3 1 5 2
4
2. 2 Hypodermis: loose connective tissue
33. Muscularis:skeletal muscle 4
4. Tarsus: dense connective tissue; tarsal glands
5 5. Palpebral conjunctiva: stratified columnar epithelium
Eyelid 1. Skin: 2. Hypodermis: 3. Muscularis: 4. Tarsus: 5. Palpebral
conjunctiva:
Three glands in eyelid 1.Tarsal glands: long sebaceous glands 2.The glands of zeis: small, modified sebaceous glands 3.The glands of moll: large, unbranched sweat glands
Tarsal glands
The glands of moll
The glands of zeis
Internal ear
The ear: sensitive to equilibrium and hearing. external ear, middle ear, internal ear
The structures of middle ear
Internal ear(labyrinth) Osseous labyrinth: perilymphatic fluid Membranous labyrinth: endolymphatic fluid
Osseous labyrinth: 1. Skeletal semicircular canals 2. Vestibule 3. cochlea
Cochlea: a spiral canal around the modiolus;
Modiolus is a cone-shaped structure composed of bone, contains the spiral ganglion.
Membranous labyrinth: 1. membranous semicircular canal 2. utricle, saccule 3. Membranous cochlear duct. Special receptor organs: maculae, crista and organ of corti.
1. Membranous semicircular canals Crista ampullaris: the receptor area in the ampullae, ridgelike structures.
The structure of Crista ampullaris Supporting cells Hair cell cilia (stereocilium, kinocilium) Geletinous, cupula afferent nerve ending
Function and mechanism of Crista ampullaris: Function: Site-receptor sensitive to the beginning and ending of the head’s spiral moving. Mechanism: the beginning or ending of the spiralmovement of the head can cause the endolymphatic fluid to move, cupula will change its position, which stimulates hair
2. The saccule and the utricle: a thin sheath of connective tissue lined by simple squamous epithelium Macula utriculi and macula sacculi: cone-shaped regions
The structure of Crista ampullaris Supporting cells Hair cell cilia (stereocilium, kinocilium) Afferent nerve ending Glycoprotein layer Otolith
Function and mechanism:
Function: sensitive to the beginning and ending of lining movement and the position of the head in the static state. Mechanism: hair cells are receptor cells. There is a membrane statoconium covering the maculae. It is heavier than endolymphatic fluid. By gravity the membrane statoconium can stimulate
Membranous cochlea duct: Scala vestibule Scala media or Membranous cochlea duct
Scala tympani
Spiral ligame nt
Vestibular membrane
Stria vascula ris Organ of corti or spiral organ Membra nous spiral lamina or
Tectori al membr ane Spiral limbus Osseous modiol spiral lamina us Spiral ganglio
Spiral organ: Supporting cells (pillar cells & phalangeal) & hair cells stereocili um Outer hair cell Outer phalang eal cell
Inner hair cell Inner tunne l Inner phalangea l cell
Inner pillar
Outer pillar
Spiral organ
Outer hair cell Outer phalangeal cell
Inner hair cell Inner tunne l outer pillar cell
inner pillar cell
Inner phalangeal cell
Function and mechanism of the spiral organ: Function: responsible for hearing. Mechanism: sound the tympanic
vibration in
membrane vibration is transmitted to internal ear the vibration of the basilar membrane
the tectorial membrane contact with the stereocilium of Cochlear nerve: the central processes of th spiral theganglion hair cells hair cells are