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Eye Histo
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 The PIGMENT EPITHELUIM LAYER THE LAYER OF RODS AND CONES |
| Which fibers become confluent at the optic papilla | Optic Nerve Fibre Layer |
| Neurons at the retina consist of what six types? | RODS CONES HORIZONTAL CELLS BIPOLAR CELLS AMARACRINE CELLS RETINAL GANGLIONIC CELLS |
| 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 |
| Müller 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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milky1989
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