Eye&ear1

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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

8

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

6

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