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41 Cards in this Set
- Front
- Back
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Eyebrows |
Overlie supraorbital margins of the skull Shade eye from sunlight Protect eyes from sweat |
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Eyelids |
Thin, folds supported laterally by connective tissue sheets (tarsal plates) Protect eye from foreign objects |
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Conjunctiva |
Transparent mucous membrane Produces a lubricating mucus that prevents the eye from drying out |
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Lacrimal Apparatus |
Consists of lacrimal gland and ducts that drain lacrimal secretion to nasal cavity Cleanses and protects the eye surface as it moistens and lubricates it |
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Extrinsic eye muscles |
Allow eyes to follow a moving object Help maintain the shape of the eyeball Hold it in the orbit |
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Fibrous layer |
Outermost coat of the eyeball Composed of dense avascular connective tissue |
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Sclera (fibrous layer) |
Forms posterior portion and bulk of fibrous layer 'white of eye' Protects and shapes the eyeball Provides sturdy anchoring site for extrinsic eye muscles |
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Cornea (fibrous layer) |
Forms window that lets light enter the eye Well supplied with nerve endings High capacity of regeneration and repair Has no blood vessels |
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Vascular layer |
Forms middle coat of eyeball |
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Choroid (vascular layer) |
Blood vessel-rich, dark brown membrane Helps absorb light Has posterior opening where optic nerve leaves |
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Ciliary body (vascular layer) |
Thickened ring of tissue that encircles the lens Control lens shape Secretes the fluid that fills the cavity of anterior segment of eyeball Helps hold lens in upright position |
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Iris (vascular layer) |
Colored part of eye Lies between cornea and the lens Allows light to enter eye Acts as reflexively activated diaphragm to vary pupil size |
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Inner layer (Retina) |
Innermost layer of eyeball Develops from an extension of the brain Contains millions of photoreceptors, glia Involved in processing responses to light |
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Pigmented layer (retina) |
Single-cell-thick lining, next to choroid Absorb light and prevent it from scattering Act as phagocytes, photoreceptor renewal Store vitamin A needed by photoreceptors |
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Neural layer (retina) |
Composed of three main neurons: photoreceptors, bipolar and ganglion cells Enhances visual activity Region used to look for signs of hypertension, diabetes, and other vascular diseases |
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Optic disk (retina)
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Where optic nerve exits eye Lacks photoreceptors |
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Rods (retina) |
Dim-light and peripheral vision receptors Do not provide sharp images or color 20 rods for every cone |
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Cones (retina) |
Vision receptors for bright light Provide high-resolution color vision |
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Central artery & Central Vein of retina |
2/3 of blood supply to retina Enter and exit through center of optic nerve |
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Vitreous humor |
Transmts light Supports posterior surface of lens Holds neural layer against pigmented layer Helps to counteract the pulling force of extrinsic eye muscles |
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Aqueous humor |
Clear fluid similar in comp. to blood plasma Forms and drains continually Supplies nutrients and oxygen to lens, cornea and retina Carries away metabolic waste |
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Lens |
Biconvex, transparent, flexible structure Changes shape to focus light on the retina Is avascular, lens fibers packed tightly Contain transparent proteins (crystallins) |
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Pathway of light: One |
Moves sequentially through cornea, aqueous humor, lens, and vitreous humor then through entire neural layer to pigmented layer |
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Pathway of light: Two |
Light is bent three times: entering the cornea, entering the lens, and leaving the lens |
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Pathway of light: Distant vision |
The ciliary muscles are completely relaxed Lens is as thin as it gets Lowest refractory power when at rest Symphatic input increase, parasympathetic input decreases |
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Pathway of light: Close vision |
Refocus includes 3 processes Accommodation of lenses Constriction of pupils Convergence of eyeballs |
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Light adaption |
Rod systems turn off Lose retinal sensitivity Gain visual acuity No transducin |
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Dark adaption |
Rhodopsin accumulates Transducin returns to outer segment Retinal sensitivity increases Pupils dilate |
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Visual processing |
Begins in retina, simplify and condense info from rods and cones Ganglion cells pass info to thalamus Then finally to primary visual cortex |
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Smell receptors (location) |
Olfactory epithelium located at roof of nasal cavity (cranial nerve I) |
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Smell receptors (structure)
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Are ciliated bipolar neurons Axons are filaments of olfactory nerve Have olfactory cilia that increase surface area |
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Smell receptors (activation) |
Excited by volatile chemicals that bind to receptors in olfactory cilia |
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Smell receptors (pathway) |
Each glomerulus represents a single aspect of an odor GABA releasing cells inhibit mitral cells Impulses flow from bulbs to tracts to cortex then to brain |
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Taste receptors (location) |
Scattered in oral cavity and pharynx Most abundant on tongue papillae |
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Taste receptors (structure) |
Gustatory epithelial cells (taste receptors) Gustatory hairs serve as receptor regions Nerves VII, IX, and X |
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Taste receptors (activation) |
Excited by binding of tastants to receptors on their microvilli Five taste qualities:sweet, sour, bitter, salt, and umami |
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Taste receptors (pathway) |
Send impulses to the solitary nucleus of medulla then to thalamus and gustatory cortex |
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External ear (structure) |
Auricle/pinna the part of the ear we see
External acoustic meatus- short tube Tympanic membrane-eardrum |
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External ear (function) |
Auricle-funnel sound waves into external acoustic meatus External acoustic meatus- earwax Tympanic membrane-vibration, transfer sound energy to middle ear |
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Middle ear (structure) |
Mastoid antrum-canal in posterior wall Pharyngotympanic tube- link middle ear cavity w/nasopharynx Stapedius- posterior wall to stapes |
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Middle ear (function) |
Mastoid antrum-allows communication w/mastoid air cells Pharyngotympanic tube- equalize pressure Stapedius-protects from loud sounds |
