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
Are highly enlongated appear as thin flattened structures with the cytoplasm becomes filled with a group of proteins called crystallins it’s specialist for light refraction
Lens fibers
The lens is held in place by fibers of the …., which extend from the lens capsule to the ciliary body
Ciliary zonules
When the eye is at rest, for distant vision ciliary muscles
Relax and the resulting shape of ciliary body puts tension on the zonule fibers, which pulls the lens into a flatter shape
Es una afección en la cual el cristalino del ojo pierde su capacidad para enfocar. Esto dificulta el hecho de ver objetos cercanos.
Presbyopia
To Focus on a close object the ciliary muscle fibers
Contract changing the shape of the ciliary body relaxing tension of the ciliary zonule allow to assume the more rounded shape
Occupies the large vitreous chamber behind the lens
Vitreous body
Percentage of connective tissue of vitreous body that represent water
99%
The only cells in the vitreous body are
Hyalocytes which synthesize the hyaluronate and collagen
Two fundamental sublayers from the inner and outer layers of ebryonic optic cup
Pigmented layer
Neural layer
Simple cuboidal epithelium of a outer sublayer of retina attached to Brunch membrane and the choroidocapillary lamina of the choroid, forms the other part of the dual epithelium covering the ciliary body and posterior iris
Pigmented layer
Inner retina region, is thick and stratified with various neurons and photoreceptors, extend anterior only as far as the ora serrata, this layer continue as part of the dual cuboidal epithelium that covers the surface of the ciliary body and posterior iris
Neural layer
The two layers (pigmented and neural)of the optic cup are not firmly joined to each other, head trauma or other conditions can cause the two layers separate
Detached retina
The pigmented epithelial layer consist of
Cuboidal or low columnar cells, well develop juntional complex, , numerous melanin granules and abundant SER
Function of retinal pigmented epithelium
Absorb scattered light Part of the protective blood retina barrier regulating ion transport of choroid Retinal regeneration (vitamin A) Phagocytosis Remove free radical
Is comprise by nine distinct layers, functions as an outpost of the CNS with glia and interconnected neuronal subtypes
Neural retina
Three major layers that contain the nuclei of the interconnected neurons
Outer nuclear layer
Inner nuclear layer
Ganglionic layer
Contains cell bodies of photoreceptors (rod & cones) near the pigmented epithelium
Pigmented layer Rod & cones layer Outer limiting layer😉 Outer nuclear layer Outer plexiform layer Inner nuclear layer Inner plexiform layer Ganglionic layer Nerve fiber layer Inner limiting layer
Contains the nuclei of various neurons, notably the bipolar cells, amacrine cells, and horizontal cells, all which Make specific connection with other neurons and integrate signal from redes and cones
Pigmented layer Rod & cones layer Outer limiting layer Outer nuclear layer Outer plexiform layer Inner nuclear layer😁 Inner plexiform layer Ganglionic layer Nerve fiber layer Inner limiting layer
Near the vitreous has neurons with much longer axons, this axons Make up the nerve fiber layer and converge to form the optic nerve , is thickest near the central macular region of the retina but is thin peripherally to only One layer
Pigmented layer Rod & cones layer Outer limiting layer Outer nuclear layer Outer plexiform layer Inner nuclear layer Inner plexiform layer Ganglionic layer 😁 Nerve fiber layer Inner limiting layer
Two fibrous regions contain only axons and dendrites connected by synapses
Outer plexiform layer
Inner plexiform layer
Include axons of the photoreceptors and dendrites of association neurons in the INL
Pigmented layer Rod & cones layer Outer limiting layer Outer nuclear layer Outer plexiform layer😊 Inner nuclear layer Inner plexiform layer Ganglionic layer Nerve fiber layer Inner limiting layer
Consist of axons and dendrites connecting neurons of the INL with ganglionic cells
Pigmented layer Rod & cones layer Outer limiting layer Outer nuclear layer Outer plexiform layer Inner nuclear layer Inner plexiform layer 😝 Ganglionic layer Nerve fiber layer Inner limiting layer
All neurons of the retina are supported physically by glial cells called
Müller cells
Is a faint but well defined series of tight and adherent junction that form at the level of the rod and cone inner segments between the photoreceptors and Müller cell processes
Outer limiting layer OLL
Consist of terminal expansion of other Müller cell processes that cover the collagenous membrane of the vitreous body
Inner limiting layer
Average of rod cells in human
92 millon
Extremely sensitive to light, respond to a single photon, vision nighttime compose by only two functionally distinct segments (inner & outer)
Rod cells
One of the only two segments of rod cells that is a modified primary cilium
Outer segment
One of the only two segments of rod cells that has glycogen, mitochondria for the cells biosynthetic activity
Inner segment
The rod shaped segment consist mainly of….. , flattened membranous discs
600 to 1000
Proteins on the cytoplasmic surface of each disc in rod cells,which is bleached by light and initiates the visual stimulus called
Rhodopsin or visual purple
Average of membranous discs that are lost and replaced in each rod each day
90
Average of cone cells
4.6 million
Pigment that cones have
Iodopsin or photopsin
Many key genes for the color sensitivity of cones are one .. Chromosomes
X
On rod contains about … Rhodopsin molecules
Billion
Each of these visual pigments contains a transmembrane protein, the opsin, with a small light sensitive chromophore in which the vitamin A derivative called
Retinal
The blind spot of the retina, lacks photoreceptors and all conducting neurons, it occurs posterior area of the retina where axons in nerve fiver layer converge to produce the optic nerve which leaves the retina, central vein and arterie enter at this point
Optic disc
Near the optic disc within the portion of the retina directly opposite the pupil a special area of 1.5mm in diameter where visual acuity or sharpness is maximal , with only cone cells at its center, ganglionic cells and other conducting neurons are located in the periphery
Fovea centralis
Surrounding the fovea centralis with 5mm in diameter , here all layers of the retina are present and to plexiform layers are rich in various carotenoids which gives this area a yellowish color,
Macula lutea
With GL of the entire retina a subset of ganglion cells serve as
Nonvisiual photoreceptors
Ganglion cells ,These neurons contain 11-cis retinal bound to the protein …., and serve to detect changes in light quantity and quality during each 24 hour dawn/dusk cycle
Melanopsin
Ganglion cells pass via axons of retinohypothalamic tract to
The suprachiasmatic nuclei and the pineal gland, where help establish the body’s physiologic circadian rhythm
Is a thin transparent mucosa that covers the exposed, anterior portion of the sclera and continue as the lining of the inner surface of the eyelids with stratified columnar epithelium with numerous goblet cells supported by a thin connective tissue
Conjuntiva
Conjunctiva epithelium
Stratified columnar
Condition in which the conjunctiva is inflamed usually due to bacterial or viral infection or to allergies increase the discharge of mucus and enlarge the microvasculature of sclera causing red appearance
Conjunctivitis or pink eyes
Are pliable structure containing skin, muscle, and conjunctiva that protect the eyes, the skin is loose and elastic, lack fat, and very small hair follicles and fine hair, except at the distal edge where large follicles of eyelashes with associated sebaceous glands and modified apocrine sweat glands,
Eyelids
In eyelids beneath the skin are
Striated fascicles of the orbicularis oculi and lavator palpebrae muscles that fold the eyelids
Adjacent to the conjunctiva is a dense fibroelastic plated called… , that support the other tissue
Tarsus
Quantity of sebaceous glands that is surrounded by tarsus, with many acini secreting into a long central duct that opens among the eyelashes
20-25
Oils in the sebum produce by these tarsal glands also called…, form a surface layer on the tear film reducing its rate of evaporation and help lubricate the ocular surface
Meibomian glands
Infections near an opening of the tarsal glands ducts, generally caused by Staphylococcus aureus, are called
Styes
Produce fluid continuously for the tear film that moistens and lubricates the cornea and conjunctiva and supplies O2 to the corneal epithelial cells
Lacrimal glands
Tear fluid contains
Metabolites
Electrolytes
Proteins of immunity such as lysozyme
The main lacrimal glands are located in
The upper temporal portion of the orbit and have several lobes
The lacrimal glands drain through
Individual excretory ducts into the superior fornix, the conjunctiva lined recess between the eyelids and the eye
The lacrimal glands have acini composed is surrounded by
Myoepithelial cells and a sparse vascular stroma
Tears film moves across the ocular surface and collect in
Other parts of the bilateral lacrimal apparatus
Lacrimal apparatus consist
Flowing through two small rounding opening(0.5 mm diameter) to canaliculi at the medial margins of the upper and lower eyelids , then passing into lacrimal sac, and finally drain into nasal cavity via nasolacrimal duct
The canaliculi of the lacrimal apparatus is lined by
Stratified squamous epithelium
Distal sac and duct of the lacrimal apparatus is lined by
Pseudostratified ciliated epithelium
Tres partes del oído
Oído externo
Oído medio
Oído interno
Conduce ondas sonoras hacia la membrana timpanica, lleno de aire y se comunica con el interior del cuerpo
Oído externo
La auricula o pabellón auricular está formado por
Cartílago elástico
Posse partes óseas y cartilaginosas y glandulas ceruminosas
Meato auditivo externo
La membrana timpanica esta cubierta por
Externamente piel delgada e internamente por epilelio plano simple
Transmite las vibraciones que percibe la membrana al oído interno
Oído medio
El oído medio se comunica con la nasofaringe a través de
Trompa de eustaquio
La cavidad timpanica esta revestida por
Epitelio cúbico simple
Huesecillos del oído medio
Martillo, yunque y estribo
Su base transmite las vibraciones por una perforación llamada ventana oval o vestibular
Estribo
Dos funciones del oído interno
Audición y equilibrio
La función auditiva del oído interno es llevada acabo por
Coclea
La función de equilibrio esta dada por
Vestíbulo
Se halla dentro del laberinto oseo , llena de liquido llamado perilinfa, dentro del cual esta el laberinto membranoso que contiene la endolinfa
Colcea
El canal espiral coclear contiene …., que está lleno de endolinfa
Conducto colear
Está localizado en el conducto coclear
Órgano de Corti
El conducto coclear se encuentra en
La rampa media
La rampa vestibular esta llena de
Perilinfa
La membrana vestibular o techo del conducto coclear tiene dos capas de epitelio
Plano o cúbico
Es el limite caudal del órgano de Corti, piso del conducto coclear
Membrana bacilar
Embebidos en la membrana rectoría y responden a la oscilación resonante de la membrana basilar
Celulas ciliares con estereocilio
Los receptores vestibulares se hallan dentro del
Laberinto membranoso
Which receives sound waves
External ear
Is an irregular funnel shape plate of elastic cartilage covered by tightly adherent skin,
Auricle or pinna
Sounds waves enter here and is a canal lined with stratified squamous epithelium that extends from auricle to the middle ear
External Acustic meatus
Found near its opening sebaceous gland that are modified apocrine sweat glands call
Ceremonious glands
Wall of the external auditory meatus in the outer third is supported by
Elastic cartilage
Membrane of fibroelastic connective tissue covered with epidermis and internally by a simple cuboidal epithelium of the mucosa that lines the middle ear cavity
Tympanic membrane or eardrum
Middle ear communicate with the pharynx via
Auditory tube or Eustachian or pharyngotympanic tube
In the middle ear which epithelium epithelium help lining the cavity rest in lamina propria continues with periosteum
Simple cuboidal
Epithelium of the auditory tube
Ciliated pseudo stratified columnar
Help balance the air pressure in the middle ear
Eustachian tube
Middle ear contains
Tympanic cavity
In the medial bone wall of the middle ear are two small membrane covered regions devoid of bone
Oval and round window
The three ossicles named
Malleus, incus, stapes
The auditory ossicles which along with periosteum are completely covered by
Simple squamous
Restrict ossicle movement and protect the oval window and inner ear from potential damage cause by loud sound
Skeletal muscle the tensor tympani and stapedium
Inflammation of middle ear caused by viral or bacterial infections extended from the upper respiratory tract via the auditory tubes
Otitis media
The membranous labyrinth is derived from
Ectodermal vesicles , the otic vesicle which invaginate into subjacent mesenchyme during fourth week
The otic vesicle or otocyst forms the membranous labyrinth with division are
Utricle and saccule
Three semicircular ducts continuous with the utricle
cochlear duct
Function of inner ear have in the epithelium lining large areas with columnar mechanoreptor cell called
Hair cells
Specialized sensory regions
2 Maculae of the utricle and saccule
3 Cristae ampullares in the enlarged ampullary regions of each semicircular duct
Spiral organ of Corti in cochlear duct
Bony labyrinth includes
Vestibule houses the saccule and utricle
Behind vestibule three osseous semicircular canals
Coclea
The cochlea contains cochlear duct, is about 35mm long and makes …. Turn around a bony core called the modiolus
2 3/4
Detect linear movement and stratic position of the head, with Maculae receptors and his membranous labyrinth component is utricle and saccule
Vestibule
Detect rotational movements of the head with cristae ampullares receptors and membranous component are semicircular ducts
Semicircular canals
Sensory receptor is organ of Corti, detect sounds
Cochlear duct
The modiolus contains
Blood vessels and surround the cell bodies and processes of the acoustic branch of the 8 cranial nerve in the large spiral or cochlear ganglion
Fills the region of the bony labyrinth with similar ionic composition similar from LCR with little proteins, suspends and support the membranous labyrinth, emerge from the microvasculature of the periosteum draining in subarachnoid space via perilymphatic duct
Perilymph
Fill the membranous labyrinth with high K (150mM) and low Na(16 mM), similar to intracellular fluid, produced in in the wall of the cochlear duct draining into venous sinuses of dura mater
Endolymph
