The Eye & Ear: Special Sense Organs Flashcards
Es la porción mas anterior de esclera
Cornea
Es el elemento retráctil mas importante del ojo
Cornea
Transparente, por fuera esta revestida por un epitelio plano muy desarrollado llamado lamina de Bowman
Cornea
Detrás de la lamina de Bowman se encuetra
Estroma corneal que es un tejido conectivo denso, avascular, con escasos fibroblastos
Segunda lamina basal de la cornea, que sirve de sostén a un epitelio plano simple que limita internamente a la cornea
Lamina de Descemet
Cámara anterior que se encuetra detrás de la cornea esta lleno de
Humor acuoso
El humor acuoso es producido por
Procesos ciliares
Es la capa que limita la cámara anterior por detrás y circunferencialmente
Iris
Aquí se encuentran las estructuras que continuamente drenan el humor acuoso y son indispensables para su recambio , con función de diafragma con el que regula la entrada de luz
Angulo camerular
Centro del iris, es un circulo cavio que forma
La pupila
Tres capas que se distinguen en el ojo de afuera hacia dentro
Esclera
Uvea
Retina
La cámara posterior esta limitada por
El iris, procesos ciliares, el cristalino, y el humor vitreo
Lente biconcava que enfoca la imagen en la retina, estructura transparente que aumenta o disminuye el espesor de su Ecuador según la imagen este más próxima o mas distal
Cristalino
Anteriormente el cristalino tiene una cápsula epitelial
Cubica o plana simple
Los niños acomodan el cristalino correctamente hasta
2 o 3 meses de edad
Llena la cavidad situada entre el cristalino y la retina, es trasparente gelatinoso, con algunas fibras de colagena y sus celulas se llaman hialocitos
Humor vitreo
Capa fotoreceptora del ojo
Retina
Capas de la retina de fuera hacia dentro
Epitelio pigmentado Fotoreceptores Membrana limitante externa Nuclear externa Plexiforme externa Nuclear interna Plexiforme interna Celulas ganglionares Fibras del nervio óptico Membrana limitante interna
Formada por conos y bastones
Fotoreceptores
Capa de color negro que impide que la luz se refleje
Epitelio pigmentado
Nucleos de los fotoreceptores
Nuclear externa
Son los nucleos de las neuronas bipolares que comunican los fotoreceptores con las neuronas ganglionares
Nuclear interna
Son las células que sensan los colores, útiles para la visión precisa concentradas en la fovea del ojo contienen pigmentos de rodopsina
Bastones
Pigmento de los conos especificos para los colores rojo,verde, y azul
Yodopsina
Los segmentos externos de sus discos se encuentran unidos con la membrana plasmatica
Conos
Su alta sensibilidad es debido a que presentan múltiples sinapsis (convergencia) , son para visión nocturna, no perciben el color, más abundantes que los conos
Bastones
Son sensibles a un simple fotón y su señal se traduce en visión blanco y negro
Bastones
External fibrous layer of eye consist in
Sclera
Cornea
Vascular layer of the eye consist in
Choroid
Ciliary body
Iris
Inner sensory layer of eyes
Retina which communicates with cerebrum through optic nerve
The lens held in place by a circular system of zonular fibers that attach it to the
Ciliary body
Partly covering the anterior surface of the lens is an opaque pigmented extension of the middle layer called
Iris
The anterior chamber is between
Cornea and iris
Posterior chamber is between
Iris and lens
The posterior vitreous chamber surrounded by the retina lies behind the lens and its zonular fibers contains a large gelatinous mass of transparent CT called
Vitreous body
Week when ebryo epithelial optic vesicles bulge bilatery from the forebrain (prosencephalon) , then elongate as the optic stalks bearing optic cup
4 week
Late week 4 a structure forms inner and outer layers, lens pit forms lense vesicles
Optic cup
Grow along the optic stalk, enter the optic cup and grow toward the developing lens
Hyaloid vessels
Differntiates as the retina and form the corneal epithelium
Ectoderm
The white posterior 5/6 of the layer is .. which enclose about 22mm in diameter in adults
Slcera
The sclera average in thickness is…, dense connective tissue and type I collagen
0.5 mm
Insert in the anterior region of the sclera
Extra ocular muscle
When sclera surround the choroid it includes an inner… ,with less collagen, more fibroblast, elastic fibers and melanocytes
Suprachoid lamina
Anterior 1/6 of the eye, transparent and avascular with an average of .9-1.2 mm
Cornea
Five layers of cornea
Stratified squamous epithelium (external) nonkeratenized
Anterior limiting membrane (bowman membrane)
Stroma
Posterior limiting membrane (descemet membrane)
Endothelium
The stratified squamous nonkeratenized epithelium have five or six layers thick comprise 10% of the corneal thickness with high proliferative capacity and emerge from stem cells in the
Corneoscleral limbus
The basement membrane of the epithelium is very thick and contributes to the stability and strength of the cornea helping to protect agains infection
Bowmans membrane
Stroma or substantia propia makes up .., consist of 60 layers of parallel collagen
90% of corneas thickness
Between the collagen lamellae are cytoplasmatic extension of cells called
Keratocytes
Helps maintain the precise organization and spacing of collagen fibrils
Proteoglycan
Lumicans
Keratan sulfate
Chondroitin sulfate
The posterior surface of the stroma is bounded by …, includes the most metabolically active cells of the cornea Na /K ATPase pumps are responsible for regulating the proper hydratation state to provide transparency
Descemet membrane
Where cornea merge sclera
Limbus
The stroma becomes at limbus…. , and descemet membrane are replace by
Vascular and less well organized
Trabecular meshworks
Bowmans membrane ends and epithelium becomes more stratified an the
Conjuntiva
Trabecular meshwork penetrates the stroma at the corneoscleral junction and allow continuous drainage of aqueous humor moving from these channels into the larger space of the
Scleral venous sinus or canal of Schlemm
Located in the posterior 2/3 of the eye the choroid consist of
Loose, well vascularized connective tissue and melanocytes
Two layers of the choroid
Choroido-capillary lamina : rich microvasculature for outer retinal layer
Brunch membrane : a thin extra cellular surrounding microvasculature and basal lamina of retinas pigmented layer
More vascular middle layer
Uvea
se presenta cuando la luz que entra al ojo se enfoca de manera incorrecta, haciendo que los objetos distantes aparezcan borrosos, es un tipo de error de refracción del ojo.
Miopia
Anomalía o defecto del ojo que consiste en una curvatura irregular de la córnea, lo que provoca que se vean algo deformadas las imágenes y poco claro el contorno de las cosas.
Astigmatismo
imperfection in the eye (often when the eyeball is too short or the lens cannot become round enough), causing difficulty focusing on near objects
Hyperopia
Anterior expansion of the uvea that encircles the lens lies posterior to the limbus
Ciliary body
Makes up must of the ciliary body’s stroma, three groups of smooth muscle , contraction of these muscle affects the shape of lens and is important in accomodation
Ciliary muscle
Arrange of about 75 ridges extending from the inner highly vascular region of ciliary body covered by double layer of low columnar epithelial cells, directly covering the stroma contain much melanin, the surface layer of cells lack of melanin and is continuous with sensory layer of the retina
Ciliary process
Aqueous humor is produced by ciliary processes into the posterior chamber and flows to the anterior chamber through
Pupil
Is a system of many radially oriented fibers composed of fibrilin 1 & 2 produced by
Nonpigmented epithelial cells on the ciliary process
Consist of dense layer of fibroblast and melanocytes with interdigitating process with lack epithelial covering
Iris
The posterior surface of the iris has two layered epithelium continuous with that covering the ciliary process, heavily filled with
Melanin
Form a partially pigmented epithelial layer and extend contractile process as the dilatator pupillae muscle
Myoepithelial cells
Smooth muscle fibers form a circular bundle near the pupil as the
Sphinter pupillae muscle
The lens three components
Lense capsule
Lens epithelium
Lens fibers
Composed of proteoglycan and type IVcollagen surrounds the lens, and provides the place of attachment for the fibers of the ciliary zonular
Lense capsule
Single layer of cuboidal cells present only in anterior surface of the lens attach basally to the lens capsule and their apical surface bind the internal lens fibers, at the posterior edge near the equator of the lens divide and provide new cells that differnciate as lens fibers
Lens epithelium