Histo Key Points Eye

Question Answer
what are the eye layers Tunica Fibrosa Uvula Tract Nerve Layer
Tunica fibrosa is made up of (sclera and cornea)
Uveal tract is made up of (choroid, ciliary body and iris)
Nerve layer made up of (retina)
Anterior chamber is made of Cornea and iris (and anterior face of the lens).
Posterior chamber consists of Iris, ciliary processes, zonular attachments and lens.
Vitreous space found where Behind the lens; surrounded by retina.
the sclera is made uo of Opaque five sixths (posteriorly) of the external laye
the scleara is thinner_____ and thicker_______ Thinner in the coronal equator and thicker posteriorly, where the optic nerve crosses it (lamina cribosa).
whats is the color of the sclera White (bluish to yellow)
what is the sclera made up of made of dense connective tissue, relatively avascular.
Episclera is what External layer connected by loose connective tissue with the Tenon’s capsule
Tenon’s capsule (sclera proper) insertion of what muscle Where extraocular muscles insert
Suprachoroidal lamina (lamina fusca) what does it consist of Loose connective tissue with melanocytes, elastic fibres and fibroblasts.
The episcleral space exists between episclera and Tenon’s capsule
Cornea is considered the Primary dioptry of the eye
Which means that cornea is responsible for most of the light____ Refraction
the conrnea is described as the Transparent anterior sixth of tunica fibrosa
what are the paramaters of the Cornea 11 mm diameter and 0.55 mm thick, with five layers
what are the five layers of the cornea epitheluim Bowman's membrane stroma Descemet's Membrane Endotheluim Limbus Aqueous Fluid Uvula Tract
Epithelium of cornea makes up what % of the tissue ~ 10 % of tissue thickness
what kind of epithelui do you find in the cornea Five to seven cells-thick stratified squamous epithelium
what kind of surface to you expect to find in the cornea Smooth refractive surface
what is the nerve supply of the cornea rich or poor Rich nerve supply
what kind of cells constitute the corneal epitheluim Surface cells with microvilli
what is the function of the surface cells with microvilli in the corneal epitheluim that helps to sustain the precorneal tear film (divided into mucous layer, aqueous layer, oily outer layer)
what is the life span of the corneal apitheluim Turnover each week
2. Bowman's membrane is characterized as Homogenous acellular layer of type II collagen and intercellular substance
what is the thickness of the Bowman's capsule 7 – 12 µm in thickness
what is the function of the Bowman's Capsule Provides stability and strength to the cornea
what does the Bowman's capsule lack of basal lamina as it lacks of glycosaminoglycans
what part of the cornea is destroyed does not regenarate Bowman's Capsule
Stroma makes up what % of corneal thickness ~ 90 % of corneal thickness
what describes the lamina of coreal stroma 60 thin lamellae of parallel intertwined collagen fibrils and intercellular substance
the intracellulat substance in the Stroma of the cornea is rich in what rich in chondroitin sulfate
what are the cells of the corneal stroma Fibroblasts (keratocytes)
what is the function of the stroma of the cornea Provides support to the cornea
Is the cornea stroma vascular or avascular Avascular
Descemet's membrane is how thick 5 – 10 µm thick structure
The Descemet's membrane is another name for lamina of the corneal endothelium
Descements Membrane is mainly made up what kind of filaments? Collagen filaments
Is the descement's membrane easily regenarated? Easily regenerated if the corneal endothelium is intact
under what conditions is the Descement's membrane easily regenarated if the corneal endotheluim is still intact
Endothelium of the cornea is Simple squamous or low cuboidal epithelium
what is the function of the Endothelial layer of the cornea? maintain Descemet’s membrane
How does the endotheluim layer dehydrate the cornea? Dehydrates cornea via Na-K ATP pump (takes out the water from stroma) [Relative dehydration maintains corneal clarity]
Does the endothelial layer of the cornea easily regenarate ? Highly specialized
Limbus is what kind of area in the cornea Transition area
what is another name for the Limbus layer of the cornea (AKA corneoscleral junction
The Limbus is the layer of the cornea that serves as a reservoir for what types of cells for what layer Stem cell reservoir for the corneal epithelium
Is the Limbus vascularized Highly vascularized
what is the charactereristic of the limbus Trabecular meshwork (loose connective tissue)
what are the spaces of Fontana and in which layer of the cornea are they found? Endothelium-lined channels (spaces of Fontana) found in the Limbus layer of the cornea
the Spaces of Fontana found in the Limbus layer create? the canal of Schlemm (sinus venosus sclerae)
Aqueous fluid is Secreted by? the ciliary processes
Aqueous fluid is rich in ascorbic acid
what is the function of the aqueous fluid Nourishes the lens and the cornea
what is the refraction of the aqueous fluid in relation with the cornea Non-refractive in relation with the cornea
where is the Aqueous Fluid Reabsorbed? In the canal of Schlemm
what is the pressure level required to maintain the shape of the cornea? Hydrostatic pressure of 20 mm Hg, maintains the shape of the cornea
Uveal tract is the (middle or vascular layer)
Four components of the uvula tract are Choroid, Ciliary body, Ciliary processes, Iris
Choroid layer of the uvula tract makes up? Posterior five sixths of the eye
what is the function of the choroid layer of the uvula tract? Creates a dark chamber and provides nutrition to the retina
the choroid layer of the uvula tract provides nutriotion to which part of the eye Retina
The choroid layer of the uvula tract is describes as Highly vascularized loose connective tissue with melanocytes
what type of cells will you find in the choroid layer of the uvula tract melanocytes
the choroid plexus is made up of Two layers what are they? Outer Layer and Choriocapillary layer
Outer layer With large blood vessels
Choriocapillary layer Inner layer, many small blood vessels
Bruch's membrane is what ? Hyaline layer from the optic disk (optic papilla) to the ora serrata (were both retinas meet each other)
The ora serrata is the place where? both of the retina's meet each other
The Bruch's membrane is a Specialized basement membrane for the retinal pigmented epithelium
what is the function of the Buchman's membrane? Separates the choriocapillary layer from the retina
The Buchman's Membrane is made up of 5 layers what are they ? Basal lamina of choriocapillary layer,Thin collagen layer,Thin layer of elastic fibres, Thin subepithelial layer of collagen fibres, Basal lamina of retinal pigment epithelium
Ciliary body is what ?
the ciliary body is found at what level at the level of the lens
what is the tissue type that we see in the ciliary body Loose connective tissue with melanocytes surrounding the ciliary muscle
what is the function of the ciliary body Secretes the aqueous humor (ciliary processes)
the ciliary body is devided in to ? Divided in anterior and posterior portions
the anterior part of the ciliary body is called Anterior (pars plicata)
Anterior Pars Plicata is 75 folds (ciliary processes) that radiate posteriorly
Posterior (pars plana) is? flat, joins the retina at the ora serrata
the Epithelium of the ciliary body ismade of? two layers of single cells continuous with the pigmented cells in the iris
which layer is pigmented in the iris? only the outer layer is pigmented
Ciliary muscles are what type of muscle Two bundles of smooth muscle
the ciliary muscle insertes where Inserted in the sclera anteriorly and on the ciliary body posteriorly
what is the function of the ciliary muscle? One bundle stretches the iris; the other relaxes the tension on the lens (provided by the zonula fibres) when contracted
what kind of innervation does the ciliary muscle receive Parasympathetic innervation
Ciliary processes is the? Ridge-like extensions of ciliary body.
ciliary processes is made up of? Core of loose connective tissue with capillaries.
where do you find the zonule fibers? From the grooves between the processes emerge the zonule fibres.
The ciliary processes are made up of? Two simple epithelial layers
The External epithelial layer of the ciliary processes is made up of Simple columnar with melanin.
The Internal epithelial layer of the ciliary processes is Derived from the retina.
the cells of the internal epithelial layers form? These cells form the aqueous humor.
Iris is a Ring-like structure
The Iris is considered to be the Extension of the ciliary body
Pupil round opening in the centre of the iris
Anterior surface of the iris is made up of ? Grooves and ridges
The Groves and Ridges in the iris are created by which cells? (melanocytes and fibroblasts)
Stroma of the iris contains? melanocytes, blood vessels and the sphincter pupillae muscle [parasympathetic innervation]
which part of the eye is considered to be an extension of the ciliary Body? Iris
The posterior surface of the iris is made up of? two layers of epithelium
The two layers of posterior surface of the iris are? Inner (inner retinal layer),Outer (outer pigmented layer)
Inner Retinal layer of the Iris is ? Pigmented, big melanin granules (stops light)
what is the function of the inner retinal layer? Stops the light
The Outer Pigmented layer in the basal regions is rich with overlapping myofilaments
The overlapping myofilaments of the outer pigmented layer create what? to create the dilator pupillae muscle of the iris (defined sometimes as contractile outer layer)
The dilator pupillae muscle is what kind of innervation [sympathetic innervation]
Colour of the eyes is provided by what three elements pigment of the STROMA OF THE IRIS, The Pigment of the Posterior epitheluim, Cellular density of the stroma of the iris
Muscles of the iris are which two Dilator and Sphinter
Dilator Muscle has this innervation and runs? Sympathetic, runs radially
Sphincter muscle of the Iris has this innervation and runs? Parasympathetic, runs concentrically
Lens is a ? Transparent biconvex epithelial structure
how thick is the lens (10 mm diameter and 5 mm thick at the centre)
the lens is responsible for the? secondary dioptry of the eye.
What keeps the Lens in Place? Zonule fibres keep it in place
What do the Zonula Fibers do in relation to the ciliary muscle? transduce the action of the ciliary body muscle
what are the 3 portions of the Lens?Capsule Subscapular Epitheluim and Fibers Capsule–Subscapular Epitheluim –Fibers
Capsule of the lens is typically this made up of? Thick carbohydrate-rich structure coating the outer surface of the lens (type IV collagen plus glycoproteins)
Subcapsular epithelium of the lens is? Single layer of cuboidal epithelial cells only in the anterior surface of the lens
Fibres of the Lens are ? Highly differentiated cells that lose their nuclei and organelles (7 – 10 mm in length x 8 – 10 µm in width)
Opacities of diverse etiology in the lens are known as cataracts.
Accommodation is the Ability of the lens to adjust to keep objects focused on the retina
Accommadation is possible due to these three structures Lens, Ciliary muscle, Suspensory ligaments (zonule fibres)
Vitreous body is a ? Jellylike substance behind the lens
Vitreous Body is made up of ? 98 % of water
Vitreouse Body makes up most of the? volume of the eye (~ 2 / 3)
The Vitreouse body is refrective non refrective in response to the lens? Non-refractive respect to the lens
Hyalocytes are cells that are found? Peripherally situated in the vitreous body
What is the function of the Hyalocytes? Synthesize and maintain collagen and hyaluronic acid
What kind of activity is displayed by the hyalocytes? Phagocytic activity (if they also have antigen presenting properties, they might come from the monocytes).
What is the possible precursor of the Hyalonocytes? Monocytes
Retina consist of two portions what are they Anterior–> Not photoreseptive
Posterior–> Photosensitive (functional Retina)
What is the limit between two portions of the Retina called? Ora Serrata
Anterior portion of the Retina is not photosensitive; just the inner lining of the ciliary body and posterior face of the iris.
Posterior portion of the Retina is or is not photosensitive? photosensitive. Functional retina.
The posterior portion of the Retina is also called the? Functional Retina
Layers of the Retina are? Pigment epithelium, Layer of Rods and Cons, external limiting layer
Layer of rods and cones is where the what is found? the cytoplasm and pigment disks are found
External limiting membrane is made up of which layers Outer nuclear layer – these are the nuclei of cones and rods
Outer Plexiform Layer
Inner Nucleur Layer
Inner Plexiform Layer
Ganglionic Cell Layer
Optic Nerve Fibre Layer
Internal Limiting Membrane
Retinal Detachment is mostly observed in which 2 layers ? 1st and 2nd layer of the retina
Which fibers become confluent at the optic papilla Optic Nerve Fibre Layer
Neurons at the retina consist of what six types? RODS
Amacrine cells make VERY COMPLEX INTERACTIONS with which types of cells? WIth each other Amacrine cells, Bipolar Cells, the Retinal Ganglionic cells and even the outer Plexiform Layer
Muller cells are what type of cells associated with what area of the eye? Glial cells for the retina
WHat is unique about the Muller Cells? Have also very precise ways of conducting light within, as if they were optical fibres.
Muller's cells conduct light as if they were ? optical fibers
The Nuclei of the Muller's Cells are found? Nuclei found at the inner nuclear layer
The Muller's Cells extend from ? internal limiting membrane to the external limiting membrane
Photorreceptors of the eye are ? RODS AND CONES
Rods are how many in the human eye and most commonly found where ? 120 million in the human retina, more abundant at the periphery.
What are Rods Sensitive to? low levels of light.
The Rods are responsibile for? Visual Perception
What do you find in the RODS ? Flattened disks with Rhodopsin (visual purple) which initiates visual stimulus.
Which substance is responsible for the initiation of the Visual Stimulus? Rhodopsin
Outer segment of the Rods is? photosensitive;
inner segment of the Rods is ? metabolic machinery.
Cones are how many in the human retina? 6 million in the human retina.
The cones have how many functional types? 3 functional types.
What do the Cones respond to? They respond to intense levels of light
What are the cones Responsible for? visual acuity
What is the pigment of the Cones? Iodopsin is their photopigment.
The nuclei of both rods and cones are present at the outer nuclear layer.
A Special retinal spot Fovea
Fovea is a ? Shallow depression of the posterior pole of the optical axis
The Fovea is divided in to? Divided in macula lutea and fovea centralis
Macula lutea lacks of and surrounds? Surround fovea centralis, it lack of blood vessels
Fovea centralis is responsible to provide most of ? visual acuity.
Fovea centralis is how many cones larger than the rest ? 100,000 cones, larger and longer than the rest.
Fovea Centralis Lacks of ? Absence of ganglion cells.
Papilla is also a special retinal spot which lacks of ? No photoreceptors(blind spot of the eye)
The papilla of the retina is also referred to as the? Blind Spot
The blind spot has an abundancy of ? Abundant ganglion cells
Site where the optic nerve is made and the blood vessels go through is the? Papilla
Clinically importance of the Papilla is? Allows the assessment of the intracraneal pressure
Accessory structures
Conjunctiva of the eye is? Thin membrane, covers the anterior portion of the eye up to the cornea and the internal surface of the eyelids
The conjuctiva of the eye has this kind of epitheluim? Stratified columnar epithelium with goblet cells
What types of cells are found in the Conjuctiva of the Eye? Langerhans cells
Eyelids are ? Movable folds of tissue that protect the eye
In the eyelids you will find what three types of glands? Meibomian Zeis Moil
Meibomian glands are found where in the eyelid? 25 in upper lid, 20 in the lower, long sebaceous glands not related with hair follicles in the tarsal plate.
Zeis glands are ? Small sebaceous glands connected with follicles of eyelashes.
Moll glands in the eyelid are Unbranched sweat glands that begin in a simple spiral and end into the eyelashes’ follicles.
Lacrimal apparatus It has four elements Lacrimal Gland Canaliculi Lacrimal Sac ans Nasolacrimal Duct.
Lacrimal gland of the eye is what kind of a gland? Serous gland that secretes the tears (including lysozyme).
The lacrimal Gland is made up of ? Glandular lobes with 6 – 12 secretory ducts that connect the gland with the superior conjunctival fornix.
The secretion goes to the lacrimal canaliculi through? the lacrimal puncta
Several minor lacrimal glands in the eyelids are called? (AKA tarsal glands).
Canaliculi in the eye are ? Superior and inferior, they create a common canaliculus before opening into the lacrimal sac
Lacrimal sac is the ? Dilated portion that lies in the bony lacrimal fossa
Lacrimal sac is found where? In the lacrimal Fossa
Nasolacrimal duct is just a ? downward continuation of the lacrimal sac.

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