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U3 - Eye
| Question | Answer |
|---|---|
| Accessory structures of eye | palpebrae, conjunctiva, lacrimal apparatus, extrinsic eye muscles |
| Palpebrae | eyelids |
| Conjunctiva | very thin, transparent membrane that line inner surface of eyelids as palpebral conjunctiva and covers white surface of eyeball as bulbar/ocular conjunctiva |
| Lacrimal apparatus | lacrimal gland and a number of ducts that drain secretions (tears/lacrimal fluid) |
| Extrinsic (external) eye muscles | small skeletal muscles insert onto white coat of the eye (sclera) and produce various types of eyeball movements, including movement that allow eyes to follow objects |
| Strabismus | misalignment of the eyes, in which an improperly controlled eye is turned either medially or laterally relative to the normal eye; can result from weakness/paralysis of extrinsic eye muscles |
| Structure of eyeball | wall is three tunics (fibrous, vascular, neural); lens divides into anterior cavity and posterior cavity; anterior is full of aqueous humor, while posterior is full of jelly-like vitreous humor |
| Fibrous tunic of eye | outermost tunic; two components are sclera and cornea |
| Sclera | tough, opaque, white coat of eyeball; forms bulk of fibrous tunic |
| Cornea | transparent, most anterior part of eyeball; allows light to enter eye |
| Limbus | junction where cornea and sclera meet |
| Scleral venous sinus/canal of Schlemm | passage through limbus; functions as a vein by which aqueous humor is returned ot the blood |
| Vascular tunic | middle tunic; three parts are choroid, ciliary body, iris |
| Choroid | posterior portion of vascular tunic; darkly pigmented and very vascular; gives blood supply to photoreceptors (cones and rods) of retina with oxygen |
| Cliary body | attached to edge of lens via suspensory ligament/ciliary zonule that allows ciliary muscle to regulate shape of lens for focusing on light rays |
| Iris | pigmented structure surrounded pupil; regulate diameter of pupil |
| Neural tunic/retina | innermost tunic; two principal subdivisions—pigmented layer and neural layer; three specific layers—layer of photoreceptor cells, layer of bipolar cells, layer of ganglion cells |
| I LOVE YOU | |
| Optic disc/blind spot | where optic nerve leaves the eyeball; does not have photoreceptors (rods and discs) |
| Rods and cones | contain light-absorbing visual pigments |
| Rhodopsin | the visual pigment found in rods; derived from modified vitamin A |
| Rods | photoreceptor that is sensitive to light, so allow us to see dim light and are associated with peripheral vision; problems can cause night blindness |
| Cones | photoreceptor that provides from detailed vision and color vision; deficit can cause color blindness; macula lutea and fovea centralis contain cones |
| Retina | receives oxygenated blood via capillaries of choroid and central artery of retina |
| Detached retina | condition that can cause blindness due to portion of retina becoming separated from choroid which separates rods and cones from supply of oxygen and nutrients causing them to die |
| Lens | divides internal eyeball into 2 cavities—anterior cavity and posterior cavity; located posteriorly to iris and pupil; focuses light; held in place by suspensory ligament/ciliary zonule |
| Presbyopia | farsightedness |
| Cataracts | clouding of lens as we age |
| Myopia | nearsightedness; occurs when light rays from distant objects fail to focus on retina and focus at a point in front of retina, intead; nearby objects can stay in focus, though |
| Posterior cavity | located behind lens; contains jelly substance called vitreous humor. |
| Anterior Cavity | located in front of lens; contains aqueous humor |
| Aqueous humor | continuously formed by capillaries in ciliary body and constantly circulates through anterior cavity; drains into canal of Schlemm |
| Glaucoma | condition caused by accumulation of aqueous humor due to blockage/slow drainage resulting in excessively high intraocular pressure; can cause blindness |
| Visual pathway to brain | axons of retina ganglion cells converge to form optic nerve which goes from back of eye to brain. |
| Optic chiasma | fibers from medial side of each eye cross over to opposite side |
| Optic tracts | comprised of bundled axons extending from optic chiasma; synapse w/ neurons in thalamus and axons extend to primary visual cortex to be processed into visual experience. |
Created by:
mbtrimm
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