Accessory Structures of the Eye

Palpebral fissure = The gap separating the upper and lower eyelids Lacrimal caruncle = A mass of soft tissue at the medial angle of the eye containing glands that produce thick secretions Tarsal glands = Glands that secrete a lipid-rich product preventing eyelids from sticking together Eyelashes = Robust hairs that help prevent foreign matter from reaching the eye

Covers the inner surface of the eyelids = Palpebral conjunctiva Produces tears that cover the conjunctiva = Lacrimal gland Transparent part of the fibrous outer layer extending from the bulbar conjunctiva = Cornea Pocket where palpebral conjunctiva joins the bulbar conjunctiva = Fornix

Lacrimal canaliculi = Canals that carry tears from the lacrimal puncta to the lacrimal sac Lacrimal puncta = Pores that collect tears from the lacrimal lake Nasolacrimal duct = Duct that carries tears from the lacrimal sac to the nasal cavity Lacrimal sac = Sac that collects tears from the lacrimal canaliculi

<p>Orbital fat = Cushions and insulates each eye Retina = Deep inner layer of the eyeball, responsible for light reception Intermediate vascular layer (uvea) = Middle layer of the eyeball, containing blood vessels and pigment Outer fibrous layer = Outermost layer of the eyeball, providing protection and structure</p> Signup and view all the answers

<p>Bulbar conjunctiva = Covers the anterior surface of the eye, extending to the edges of the cornea Conjunctivitis (pinkeye) = Inflammation of the conjunctiva Conjunctiva = Mucous membrane covered by an epithelium Palpebral conjunctiva = Covers the inner surface of the eyelids</p> Signup and view all the answers

<p>Contains blood vessels and pigment = Intermediate vascular layer (uvea) Deep inner layer responsible for light reception = Retina Outermost layer providing protection and structure = Outer fibrous layer Cushions and insulates each eye = Orbital fat</p> Signup and view all the answers

<p>Aqueous humor = Provides nutrition and maintains the shape of the cornea Vitreous body = Maintains the shape of the eyeball and holds the retina in place Sclera = Provides structural support and protection for the eyeball Cornea = Refracts (bends) light entering the eye</p> Signup and view all the answers

<p>Lateral angle (lateral canthus) = Point where the eyelids connect laterally Medial angle (medial canthus) = Point where the eyelids connect medially Palpebral fissure = The gap separating the upper and lower eyelids Eyelids (palpebrae) = Continuation of the skin that helps lubricate and clean the eye surface</p> Signup and view all the answers

<p>Produces tears that contain lysozyme = Lacrimal gland Pocket where palpebral conjunctiva joins bulbar conjunctiva = Fornix Carries tears from the lacrimal sac to the nasal cavity = Nasolacrimal duct Antibacterial enzyme found in tears = Lysozyme</p> Signup and view all the answers

<p>Iris = Colored part of the eye, controls the amount of light entering Pupil = Central opening of the iris, allowing light to pass through Choroid = Highly vascular layer supplying nutrients and oxygen to the retina Ciliary body = Attaches to the iris and produces aqueous humor</p> Signup and view all the answers

<p>Ciliary muscle = Contracts to change the shape of the lens for focusing Ciliary zonule = Attaches the lens to the ciliary body Lens = Refracts light to focus it on the retina Ora serrata = Serrated anterior edge of the neural layer of the retina</p> Signup and view all the answers

<p>Eyeball = Hollow, fluid-filled structure with two interior cavities Conjunctive = Mucous membrane covering the eye surface Orbital fat = Cushions and insulates the eye Lacrimal apparatus = Produces, distributes, and removes tears</p> Signup and view all the answers

<p>Rods = Sensitive to low light, responsible for black, white, and gray vision Cones = Responsible for color vision, provide sharp and detailed vision Macula = Area of high cone density, responsible for central vision Fovea centralis = Center of the macula, site of sharpest color vision</p> Signup and view all the answers

<p>Photoreceptors = Convert light energy into electrical signals Bipolar cells = Connect photoreceptors to ganglion cells Ganglion cells = Transmit visual information from the retina to the brain Optic disc = Origin of the optic nerve, where nerve fibers exit the eye</p> Signup and view all the answers

<p>Sclera = White, opaque outer layer of the eyeball Cornea = Refracts light entering the eye Corneoscleral junction = Border between the cornea and sclera</p> Signup and view all the answers

<p>Iris = Colored part of the eye, controls the amount of light entering Pupillary muscles = Change the diameter of the pupil Ciliary body = Attaches to the iris and produces aqueous humor Choroid = Highly vascular layer supplying nutrients and oxygen to the retina</p> Signup and view all the answers

<p>Ciliary body = Produces aqueous humor and controls lens shape Lens = Focuses light onto the retina Vitreous body = Helps maintain eye shape and holds the retina in place Iris = Controls the amount of light entering the eye</p> Signup and view all the answers

<p>Pigmented layer = Absorbs light that passes through the neural layer Neural layer = Contains photoreceptors and neurons for processing visual information Photoreceptors = Convert light energy into electrical signals Optic nerve = Transmits visual information from the eye to the brain</p> Signup and view all the answers

<p>Cataracts = Clouding of the lens, often caused by aging Glaucoma = Increased pressure within the eye, damaging the optic nerve Astigmatism = Blurry vision due to an irregularly shaped cornea Myopia = Nearsightedness</p> Signup and view all the answers

<p>Anterior cavity = Filled with aqueous humor Posterior cavity = Filled with vitreous body Aqueous humor = Provides nutrition and maintains the shape of the cornea Vitreous body = Maintains the shape of the eyeball and holds the retina in place</p> Signup and view all the answers

<p>Macula = Area of high cone density, responsible for central vision Fovea centralis = Center of the macula, site of sharpest color vision Optic disc = Origin of the optic nerve, where nerve fibers exit the eye, lacking photoreceptors (blind spot) Rods = Sensitive to low light, responsible for black, white, and gray vision</p> Signup and view all the answers

<p>Refraction = Bending of light as it passes through different mediums Focal point = The point where light rays converge after passing through the lens Accommodation = The ability of the eye to adjust focus for different distances Wavelength = The distance between two successive crests or troughs of a wave</p> Signup and view all the answers

<p>Aqueous humor = Clear fluid that fills the anterior chamber of the eye Vitreous humor = Jelly-like substance that fills the posterior chamber of the eye Crystallins = Proteins that make up the lens and provide its focusing power Ciliary zonule = Fibrous structure that holds the lens in place</p> Signup and view all the answers

<p>Intraocular pressure = Pressure exerted by the aqueous humor within the eye Senile cataracts = Cataracts that develop as a result of aging Suspensory ligaments = Alternative name for the ciliary zonule Canal of Schlemm = Structure where aqueous humor drains from the eye</p> Signup and view all the answers

<p>Visible spectrum = The range of wavelengths of light that humans can see ROY G BIV = Mnemonic for the colors of visible light Photons = Packets of light energy with specific wavelengths Wavelength = Distance between two crests or troughs of a light wave</p> Signup and view all the answers

<p>Accommodation = Automatic adjustment of the lens for clear vision at different distances Focal point = Point where light rays converge after passing through the lens Focal distance = Distance between the center of the lens and the focal point Astigmatism = Condition where light is not refracted properly due to an uneven cornea</p> Signup and view all the answers

<p>Anterior chamber = Space between the cornea and the iris Posterior chamber = Space between the iris and the lens Posterior cavity = Large cavity behind the lens, filled with vitreous humor Anterior cavity = Small cavity in front of the lens, filled with aqueous humor</p> Signup and view all the answers

<p>Aqueous humor = Clear fluid that nourishes the cornea and lens Vitreous humor = Gelatinous substance that helps maintain eye shape and supports the retina Intraocular pressure = Pressure exerted by the aqueous humor within the eye Scleral venous sinus = Structure where aqueous humor drains from the eye</p> Signup and view all the answers

<p>Lens = Transparent structure that focuses light onto the retina Ciliary zonule = Fibrous structure that holds the lens in place Crystallins = Proteins that make up the lens and provide its focusing power Cataracts = Clouding of the lens, often caused by aging</p> Signup and view all the answers

<p>Emmetropia = Normal vision Myopia = Nearsightedness Hyperopia = Farsightedness Scotoma = Abnormal, permanent blind spot</p> Signup and view all the answers

<p>Outer segment = Contains membranous discs with visual pigments Inner segment = Contains major organelles Rods = Detect pressure or absence of photons Cones = Provide information about wavelengths of photons</p> Signup and view all the answers

<p>Visual pigments = Absorb pigments Rhodopsin = Visual pigment found in rods Opsin = Protein component of visual pigments Retinal = Pigment component of visual pigments</p> Signup and view all the answers

<p>Absorption of a photon = Changes retinal from 11-cis to 11-trans form Activation of opsin = Triggers activation of transducin Activation of transducin = Activates phosphodiesterase Activation of phosphodiesterase = Reduces levels of cyclic GMP</p> Signup and view all the answers

<p>Photoreceptors = Transduce light into electrical signals Bipolar cells = Relay signals from photoreceptors to ganglion cells Ganglion cells = Generate action potentials that travel through the optic nerve Visual cortex = Processes and interprets visual information</p> Signup and view all the answers

<p>Visual acuity = Clarity of vision 20/20 vision = Normal visual acuity 20/15 vision = Better than normal vision 20/30 vision = Slightly worse than normal vision</p> Signup and view all the answers

<p>Protanopia = Red color blindness Deuteranopia = Green color blindness Tritanopia = Blue color blindness Achromatopsia = Complete color blindness</p> Signup and view all the answers

<p>Bleaching = Splitting of rhodopsin into retinal and opsin 11-trans retinal = The form of retinal after absorbing a photon 11-cis retinal = The form of retinal before absorbing a photon Regeneration = Conversion of 11-trans retinal back to 11-cis retinal</p> Signup and view all the answers

<p>Image formation = Process of forming an image on the retina Reversal = Compensation for the upside-down and reversed image on the retina Visual cortex = Processes and interprets visual information Perceptual constancy = Our ability to perceive objects as having constant properties despite changes in their appearance</p> Signup and view all the answers

<p>Photorefractive keratectomy (PRK) = Computer-guided laser shapes the cornea LASIK = Variation of PRK involving a flap of corneal tissue Glasses = Refractive lenses used to correct vision Contact lenses = Refractive lenses placed directly on the cornea</p> Signup and view all the answers

<p>Optic chiasm = Point where optic nerves partially cross Optic radiation = Projection fibers linking lateral geniculates with visual cortex Optic disc = Area where axons from ganglion cells converge Optic nerve (II) = Nerves carrying visual information toward the diencephalon</p> Signup and view all the answers

<p>Ganglion cells = Monitor specific portions of the field of vision Bipolar cells = Connect photoreceptors to ganglion cells Photoreceptors = Convert light energy into neural signals Horizontal cells = Lateral interactions between photoreceptors and bipolar cells</p> Signup and view all the answers

<p>Dark-adapted state = Visual pigments are fully receptive to stimulation Light-adapted state = Rates of bleaching and reassembly of visual pigments are balanced Retinal = Light-sensitive molecule that recombines with opsin Opsin = Protein component of visual pigments</p> Signup and view all the answers

<p>Night blindness (nyctalopia) = Results from vitamin A deficiency Retinitis pigmentosa (RP) = Inherited disease causing progressive retinal degeneration Depth perception = Comparing relative positions of objects in images from both eyes Field of vision = Combined visual images from left and right eyes</p> Signup and view all the answers

<p>M cells = Monitor rods, providing information about general form, motion, and shadows P cells = Monitor cones, providing information about edges, fine detail, and color On-center neurons = Excited by light in the center of their receptive field, inhibited by light at edges Off-center neurons = Excited by light at the edges of their receptive field, inhibited by light in the center</p> Signup and view all the answers

<p>Central Processing = Information travels to the visual cortex in the occipital lobe Circadian rhythm = Daily pattern of activity tied to the day-night cycle established from visual information Visual cortex = Area where visual information is interpreted and processed Brainstem = Part of the brain that receives visual information and influences circadian rhythm</p> Signup and view all the answers

Structures that provide protection, lubrication, and support for the eyes, including eyelids, conjunctiva, and lacrimal apparatus.

Skin continuation that blinks to keep the eye lubricated and clean; creates palpebral fissure.

The gap that separates the upper and lower eyelids.

Robust hairs that prevent foreign matter from reaching the eye.

A mucous membrane epithelium covering the eye, vital for lubrication and protection.

Inflammation of the conjunctiva, often leading to redness and irritation.

System that produces, distributes, and removes tears to maintain eye moisture.

Transparent part of the outer layer of the eye, helps focus light onto the retina.

Three different layers of the eye: outer fibrous, intermediate vascular (uvea), and deep inner (retina).

Muscle that controls the lens shape and divides the eye into cavities.

Fluid in the anterior cavity that circulates and maintains intra-ocular pressure.

Fluid pressure from the aqueous humor, essential for eye shape.

Condition characterized by elevated intra-ocular pressure.

Gelatinous mass in the posterior cavity that stabilizes eye shape.

Transparent structure that focuses light onto the retina; held by ciliary zonule.

Loss of transparency or cloudiness in the lens, often due to aging.

Specific point where light rays intersect on the retina.

Bending of light as it passes through the cornea and lens.

Automatic adjustment of the lens to focus on objects at varying distances.

A condition resulting from vitamin A deficiency that impairs vision in low light.

Cells in the retina that receive signals from bipolar cells and monitor areas of vision.

Ganglion cells that monitor rods, providing information on motion and general shapes.

Ganglion cells that monitor cones, offering details about color and edges.

The point where optic nerves cross, allowing visual information from each eye to integrate.

Daily activity patterns linked to the day-night cycle, influenced by visual cues.

Images arrive at the retina upside down and reversed before the brain compensates.

Clarity of vision, typically measured as 20/20. 20/15 is better, and 20/200 is legally blind.

An abnormal, permanent blind spot caused by optic nerve compression or damage.

Normal vision where light focuses directly on the retina without correction.

Nearsightedness, where distant objects appear blurry.

Farsightedness, where close objects appear blurry.

Rods and cones in the retina that detect light and convert it into electrical signals.

Pigments like rhodopsin that absorb light and begin the photoreception process.

Provided by three types of cones: blue, green, and red, each responsive to different wavelengths.

Process where rhodopsin splits into retinal and opsin after absorbing light, requiring ATP for regeneration.

The small front section of the eyeball filled with aqueous humor.

The large back section of the eyeball filled with vitreous body.

The white outer layer of the eyeball, providing structure and protection.

The colored part of the eye that controls the size of the pupil.

The central opening of the iris that regulates light entry.

Photoreceptors responsible for black-and-white vision and low light sensitivity.