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106 Cards in this Set

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  • Back
The visual system is housed within the____________?
Bony Orbit
Name the four walls of the bony orbit?
Roof
Medial wall
Lateral wall
Floor
Name the 5 accessory structures of the eye?
Eyebrows
Eyelids (palpebrae)
Conjunctiva
Lacrimal apparatus
Extrinsic eye muscles
What is the function of the eyebrows?
To shade the eye and to prevent moisture (mostly perspiration) and rain, from flowing into the eye.
What is the scientific name for the eyelids?
Palpebrae
What is the function of the palpebrae?
To protect and moisten the eye.
What is the function of the eyelashes?
To protect the eye from debris and to provide a reflexive warning when objects near the eye. Eyelashes also aid in the secretion of lubricating sebum from the ciliary glands at their base.
What are conjunctiva?
Clear, epithelial, mucous membrane (cells and underlying basement membrane) that cover the sclera (white of the eye) and line the inside of the eyelids.
Which conjunctiva covers the sclera?
Bulbar conjuctiva
Conjunctivitis can be cause by bacteria, allergies or viruses. Conjuctivitis in only one eye is generally associated with which of these causes?
Bacterial infection
What are caruncles?
Small, red mound of tissue in the medial corner of the eye that contains modified sebaceous (oil) and sweat glands.
Which muscle keeps the eyelid raised?
Levator palpebrae superioris
Which muscle closes the eyelids?
Orbicularis oculi
Modified oil glands producing secretions that keep the inner eyelid lubricated are________?
Tarsal glands
Tarsal glands are embedded within the ___________?
Tarsal plate
Styes are inflammation of the ciliary glands at the base of the eyelids. What are chalazions.
Inflammation of blocked tarsal glands, usually on the upper eyelid.
What is the physiologic system containing the orbital structures for tear production and drainage?
Lacrimal apparatus
Liquid tears are secreted from the lacrimal gland. What are the main components of tears?
Water, salts, mucus, lysozyme
Lacrimal glands are located in the ______________________?
The upper, outer portion of each orbit.
What is the function of lysozynmes in tears?
To lyse bacteria, thus serving as inate antibiotics.
Tears first drain into the _____________, then enter the ___________ before draining into the _______ and nasal cavity via the naslacranial duct.
Puncta → Lacrimal canaliculi → Lacrimal sac → Nasolacrimal duct → Nasal cavity
Reflex tearing, as in response to eye irritants, is a sensory response controlled by the 5th (trigeminal) cranial nerve. Which nerve controls the parasympathetic motor pathway that results in emotional tearing or “crying”?
The 7th (facial) cranial nerve
The parasympathetic branch of the autonomic system controls the lacrimal glands via the neurotransmitter acetylcholine, through both the nicotinic and muscarinic receptors. Which receptor(s) are involved in lacrimal secretion due to fight-or-flight stimuli?
α1-receptors
Which drug would produce more lacrimal secretions, amitriptyline or pilocarpine?
Pilocarpine
Name the six extrinsic eye muscles
Superior rectus
Inferior rectus
Lateral rectus
Medial rectus
Superior oblique
Inferior oblique
Four of the six extrinsic eye muscles are innervated by the oculomotor (3rd cranial) nerve. Name these four extrinsic eye muscles.
Superior rectus
Inferior rectus
Medial rectus
Inferior oblique
Name the condition in which the eyes will not align properly?
Strabismus
Double vision is also known as?
Diplopia
Name the three layers of the outer wall of the eyeball starting from the outermost layer.
Sclera
Choroid (uvea)
Retina
Which layer of the eyball is the vascular layer?
Choroid (uvea) layer
Which layer of the eyeball is the is the neural layer?
Retina
The sclera is also known as the ________ layer.
Fibrous layer
Transparent front (anterior) portion of the fibrous layer that covers the iris, pupil, and anterior chamber?
Cornea
Protects and provides shape to the inner structures of the eyeball?
Sclera
Anchoring site for the six extrinsic eye muscles?
Sclera
The sclera is mainly comprised of ______ _______ fibers.
Dense collagen fibers
Light first enters the eye through the cornea. The cornea is avascular, true or false?
True
Name the five layers of the cornea?
Corneal epithelium
Bowman's layer
Corneal stroma
Descemet's membrane
Corneal endothelium
Thick, transparent layer consisting of regularly-arranged collagen fibers along with sparsely populated keratocytes. Consists of approximately 200 layers of type I collagen fibrils and forms 90% of the corneal thickness and serves as hydrophilic barrier.
Corneal stroma
Thin, acellular layer that serves as the modified basement membrane of the corneal endothelium.
Descemet's membrane
Tough layer that protects the corneal stroma, consisting of irregularly-arranged collagen fibers.
Bowman's layer
Simple squamous or low cuboidal monolayer of mitochondria-rich cells responsible for regulating fluid and solute transport between the aqueous and corneal stromal compartments. Also forms lipophilic barrier.
Corneal endothelium
Air-tear film interface, the most significant component of the total refractive power of the eye. Also resistant to lypophilic drugs?
Corneal epithelium
Posterior portion of the vascular layer of the eye that provides nutrients to the inner structures of the eye? Highly pigmented, this structure absorbs light and prevents light from scattering.
Choroid
Anterior portion of the vascular layer of the eye?
Ciliary body
Name the three structures of the ciliary body?
Ciliary processes
Ciliary zonule/suspensory ligaments
Ciliary muscles
Holds the lens in place?
Ciliary zonule/suspensory ligaments
Complex of vasculature and epithelium responsible for producing and secreting aqueous humor?
Ciliary processes
Controls the shape of the lens?
Ciliary muscles
Other structure of the vascular layer of the eye that is continuous with the ciliary body and is located between the cornea and lens?
Iris
Contracts and expands in response to circular and radial muscles to make the pupil larger or smaller?
Iris
Constricts the pupil (miosis) in response to bright light and close vision? Under parasympathetic control.
Circular muscles/sphincter pupillae
Pigmented structure that colors the eye?
Iris
Dilates the pupils (mydriasis) in response to dim light and distant vision? Under sympathetic control.
Radial muscles/dilator pupillae
Name the two layers of the retina?
Pigmented layer and neural layer
Retinal layer involved in photo-transduction (actual vision)?
Neural layer
What are the three main functions of the pigmented layer of the retina?
Single cell layer that absorbs light and prevents scattering
Removes old photoreceptor cells and provides local storage of vitamin-A.
Structure that divides the anterior segment from the posterior segment of the eye?
Lens
Two divisions of the anterior segment of the eye?
Anterior and posterior chambers
The bulk of the lens is made up of _______?
-Lens fibers
-No nuclei, few organelles
-Crystallins: transparent, folded proteins that form body of lens
Cuboidal cells on anterior lens surface that differentiate into lens fibers?
Lens epithelium
Clouding of the lens caused by clumping of crystallins?
Cataracts
Cause of cataracts?
Inadequate delivery of nutrients to deeper lens fibers
Aqueous humor produced by the ciliary body is circulated through the posterior chamber of the anterior segment and enters the anterior chamber through the pupil. Where does this aqueous humor drain?
Through the scleral venous sinus (Canal of Schlemm).
Purpose of aqueous humor?
To supply oxygen and nutrients to the anterior portion of the eye and to transport metabolic waste away from the eye.
What substance is responsible for maintaining intraocular pressure in the eye?
Aqueous humor
Blocked drainage of aqueous humor causes intraocular pressure to rise, compressing the retina and optic nerve. This can lead to __________.
Glaucoma
Gel like substance that fills the posterior portion of the eye?
Vitreous humor
Function of vitreous humor?
To maintain the global shape of the eyeball and to hold the neural layer of the retina against the pigmented layer of the retina.
The spectrum of visible light is?
400-700 nm
Photoreceptors absorb different wavelengths of light. Cone cells absorb light from blue (420 nm) to green (530 nm) to red (560 nm). What is the color and wavelength of light absorbed by rod shaped cells?
Green at 500 nm
Which type of photoreceptor cell provides low light and peripheral vision?
Rods
Which type of photoreceptor cells are most prevalent in the eye?
Rods
Cone shaped photoreceptor cells are specialized for?
Color vision and high visual acuity
Which cells transmit signals from the photoreceptors to the ganglion cells?
Bipolar cells
Ganglion cells are attached to the __________.
Optic nerve
Which cells in the eye are responsible for action potentials?
Ganglion cells
There are two type of interneurons dispersed throughout the neural layer of the eye. Name these interneurons?
Horizontal cells and amacrine cells
What is the function of interneurons in the neural layer of the eye?
To modify signals going to the bipolar and ganlgion cells
What is the function of the horizontal cells in the neural layer of the eye?
To synapse with photoreceptors and bipolar cells
What is the function of the amacrine cells in the neural layer of the eye?
To synapse with bipolar and ganglion cells
Name the structure in the neural layer of the eye where the optic nerve leaves the eye.
Optic disk
The optic disk is also known as the?
Blind spot
Where does the vasculature enter the eye?
Through the optic disk
Which blood vessels supply the outer third of the eye?
Choroid vessels
Which blood vessels supply the inner two thirds of the eye?
Central artery and central vein of the retina
Lateral to the optic disc is an area that contains mostly cones. Within this area is a small groove called the Fovea Centralis that contains only cones. Name this structure.
Macula lutea
Any visual image requiring high accuity is focused onto the _____________.
Fovea centralis
Name the four main segments of photoreceptor cells.
Outer segment
Inner segment
Cell body
Inner fiber
Which segment of photoreceptor cells contains the receptor region?
Outer segment
Which segment of photoreceptor cells contains the pigment and changes shape when light is absorbed?
Outer segment
In which type of photoreceptor cell is the Inner segment directly connected to the cell body?
Cones
Which type of photoreceptor cell has an outer fiber
Rods have outer fibers
Rods and cones both contain a visual pigment. What is the pigment in rod cells?
Rhodopsin
Name the two main components of rhodopsin?
Retinal and opsin
Which rhodopsin component determines the wavelength of light absorbed and involves a conformational change that causes the activation of the phototransduction cascade?
Opsin
The absorption of a photon of light results in the photoisomerisation of ______________?
Retinal (11-cis retinal to all-trans retinal)
Which comes first, photoisomerization of retinal or the conformational change of opsin?
Photoisomerization of retinal
What other term is used to describe photoisomerization of retinal?
Bleaching of retinal
In which segment of photoreceptor cells are the cation channels located?
Outer segment
The cation channels are open in the dark or in the presence of light?
In the dark
What happens when light is absorbed and 11-cis retinal is converted to trans-retinal?
The G-protein, transducin, becomes activated
Transducin activates phosphodiesterase (PDE) and PDE converts cGMP into GMP, closing the Na+ and Ca+ cation channels. What is the result of closing the cation channels?
Hyperpolorization
How can hyperpolorization lead to an action potential?
Hyperpolorization of the photoreceptor cells halts glutamate release at the synapse with the bipolar cell. Glutamate is inhibitory in this mechanism.
How does the halting of glutamate release from the photoreceptor cell depolorize the bipolar cell?
Inhibitory glutamate is no longer available to block calcium release in the bipolar cell and calcium release in the bipolar cell leads to the release of excitatory glutamate at the synapse between the bipolar cell and the ganglion.
The process is the same for cones except the visual pigment is ______________ instead of rhodpsin.
Iodopsin