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131 Cards in this Set
- Front
- Back
4 traditional special senses:
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sight, smell, taste, hearing
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5th special sense:
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equilibrium
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explain touch:
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activity of all the senses as part of the nervous system
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where are equilibrium receptors housed?
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ear
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special sensory receptors are what kind of cell?
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distinct receptor cells
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our dominant sense?
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vision
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___% of sensory receptors in the body are found where?
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70 % / eyes
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how much of eye's surface is visible to us?
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1/6 th
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eye's accesory structures?
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eyebrows, eyelids, conjunctiva, lacrimal apparatus & extrisic eye muscles
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eyebrows' purposes?
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1. shade the eyes from sunlight 2. block forehead sweat from reaching eyes
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another name for eyelids?
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palpebrae
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2 eyelids seperated by?
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palpebreal fissure
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2 eyelids meet @ 2 ends of eye @ what?
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medial & lateral commissures (canthi)
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extra bit of flesh @ medial closure called what?
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lacrimal caruncle ("a bit of flesh")
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what do Asians have in their eyes that is different?
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epicanthic fold - (vertical fold of skin)
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eyelids are supported by?
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tarsal plates (connective tissue plates
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what msucle encircles the eye & what is it anchored to?
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levator palpebrae superioris muscles - anchored to the tarsal plates
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how often do we blink?
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every 3-7 seconds
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name 2 eye glands & their functions
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1. tarsal glands (modified sebaceous glands - produce oily lubrication for eyelid & eye) 2. ciliary glands (smaller sebaceous glands between the eyelashes)
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chalazion
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"swelling" - infection of a tarsal glad that creates a cyst.
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sty
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inflamation of a smaller eye gland
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conjunctiva & its purpose?
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eye's transparent mucous membrane - produces lubricating mucus & prevents eyes from drying out
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conjunctiva sections?
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palpebral conjunctiva (lines the eyelids), and bulbar conjunctiva (covers all but cornea - is very thin)
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space between conjunctiva-covered eyeball & eyelids?
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conjunctival sac (where a contact lens fits)
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conjunctivitis
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inflammation of the conjunctiva
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pinkeye
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bacterial or viral infection of the conjunctiva
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consists of lacrimal gland & its ducts? (& its purpose)
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lacrimal apparatus - drains excess lacrimal secretions into nasal cavity
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where is lacrimal gland (& its purpos)
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in orbit above lateral end of eyeball - releases dilute saline solution
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dilute saline solution released by lacrimal gland?
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lacrimal secretion or TEARS
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name the 4 rectus muscles and where they originate?
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superior, inferior, lateral, and medial rectus muscles - they originate at the annular ring
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2 additional extrinsic eye muscles
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superior oblique & inferior oblique
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why do we have the 2 obliques?
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the superior & inferior recti muscles can't elevate/depress eye without also turning it medially - these prevent this
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which cranial nerves contraol the 6 extrinsic eye muscles?
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all are controlled by occularmotor nerve EXCEPT lateral rectus (controlled by VI - Abducens, and Superios oblique - controlled by IV - troclear)
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name for seeing 2 diff images of same scene when drunk, etc?
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diplopia (double vision) - movements of extrenal muscles not coordinated (also from paralysis/weakness of extrinsic eye muscles)
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cross-eyed?
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Strabismus - congenital weakness of extrenal eye muscles
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3 layers (or tunics) of the eyeball? (f rom outer to inner)
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fibrous, vascular, & sensory ( or retina) layers
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make-up of the outer layer?
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dense avascular connective tissue
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fibrous tunic's 2 parts (& respective functions)?
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sclera (protects & shapes eyeball - insertion point for extrinsic muscles - continuous w/brain's dura matter) & cornea (window - lets light enter the eye - part of light-bending apparatus)
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another name for the vascular layer?
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uvea ("grape")
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3 major parts (& their functions) of the vascular layer?
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iris (alolows light in through pupil, dilates & constricts pupil w/2 smooth muscle layers), & Choroid (blood vessels bring nutirion to all layers, brown pigment absorbs light to stop reflection & resulting visual confusion), Ciliary body (important in controlling lens shape)
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what suspends the lens?
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ciliary zonule (or suspensory ligament)
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What secretes fluid into the anterior cavity of the eyeball?
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ciliary processes (contains capillaries to secrete the fluid)
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pupil constricts when?
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in near vision, bright light, when subject matter is appaling, in response to fear, & during problem solving
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the pupil dilates when?
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in distant vision and dim light, or durinf appealing subject matter,
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pupil dilation is controlled by?
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sympathetic nerve fibers
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pupil constriction is controlled by?
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parasympathetic nerve fibers
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irises contain what kind of pigment?
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only brown - (if there is limited pigment, light's wavelengths are scattered from unpigmented parts, and appear blue, grey, green, etc. w/this, the pigment is usually found on the back side of the iris)
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what are the 2 layers of the retina? (& functions)
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outer pigmented layer (absorb light to prevent scattering within the eye - also act as phagocytes to eat bad photoreceptor cells & store vitamin A), and inner neural layer (transparent, contains millions of photoreceptors, involved neurons, & glia).
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fusion between retina's iner neural layer & posterior margin of the ciliary body?
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ora serrata ("saw-toothed margin")
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3 types of neurons in neural layer?
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(from posterior 2 anterior): 1. photoreceptors 2. bipolar cells 3. ganglion cells
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fundus?
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posterior wall of the eye
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optic disc
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weak spot in the fundus - also called the blind spot
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rods
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4 dim light & peripheral vision. Can't provide sharp detail in images, or color vision
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cones
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bright light & provide high acuity(detail) images
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macula lutea
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lateral to the optic disc (blind spot), located escatly at eye's posterior pole, oval region
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fovea centralis
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tiny pit in middle of the macula lutea, contains only cones, NO layers in the way, so light gets directly to the cones - where light SHOULD hit naturally -glasses fix this if its not the case
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posterior segment
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large cavity filled with vitreous (glassy) humor - binds large amounts of waterm - formed embroyogically - its what reflects the sounds waves in an ultrasound
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3 purposes of the vitreous humor
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1. TRANSMITS light 2. SUPPORTS posterior surface of lens & holds neural retina firmly against the pigmented layer 3. adds 2 INTRAOCULAR PESSURE
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2 chambers of the anterior segment (& locations)
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1. anterior chamber (between cornea & iris) 2. posterior segment (between iris and lens)
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aqueous humor
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similar to blood plasma - fills anterior segment drains regularly & in constant motion - usually at about 12-20 mmHg (16 = normal)
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scleral venous sinus
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venous channel - encircles the eye drains the aqueous humor into the venous blood vessels
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glaucoma
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excessive pressure within the eye - happens if the drainage of aqueous humor is blocked
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lens
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crystalline (protiens aligned parallel-ly) - allows light to focus on the retina
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cataract
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clouding of the lens when protiens lay down differently - from nutrients not diffusing into the lens right
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diabetic cataracts
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looks like a peace sign on the eye
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refelction of light
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when it bounces at a right angle
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refraction of light
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when it bounces at an OBLIQUE angle
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passage of light into the eye?
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bends 3 times: 1. enters cornea (bends) 2. enters lens (bends) 3. leaves the lens (bends)
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emmetropic
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20/20 vision - normal - 20 feet away is farthest point @ which there is no change in lens shape is needed 2 focus
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adjustments eye makes for close vision
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1. ACCOMODATION of lenses 2. CONSTRICTION of pupils 3. CONVERGENCE of eyeballs
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accomodation
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increases refractory power of the lens
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presbyopia
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"Old person's vision" when you hit ~age 50, the lens won't bend any more, loss of flexibility = less ability to focus
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constriction of pupils
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step 2 of close vision focusing: makes pupil smaller
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convergence
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medial rotation of the eyeballs so each is directed toward the object being viewed (controlled by somatic motor fibers of occularmotor nerves(III), and medial rectus muscles)
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myopia
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"short vision" near sightedness - can't see distance - their light focuses in front of the retina
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hyperopia
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"far vision" far-sightedness - can't see close objects
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astigmatism
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unequal curvatures in cornea or lens (badly shaped eye) = blurry images
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outer segment of rods & cones
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RODS: slender/rod-shaped CONES: short & conical
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inner segment of rods & cones
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connects to cell body, which is continuous with the inner fiber bearing synaptic terminals
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visual pigments (photopigments)
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change shape as they absorb light - embedded in the disc areas of the plasma membrane
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how do photoreceptors respond to damage
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they don't - they're very vulnerable to damage and immediately begin to degenerate if the retina becomes detached - BUT also regenerate very quickly in normal situations
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what can stop regeneration of photoreceptors?
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Vitamin A shortage (these regenerate every day)
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retinal
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photopigment that combines protien called opsins to produce 4 different visual pigments
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rhodopsin
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purple pigment - important for low light situations
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what happens with photons hit an 11-cis isomer?
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it twists and snaps into a new configuration - the all-trans isomer
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excitation of rods happens when?
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low-light - rhodopsin is necessary
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bleaching of the pigment
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happens when rhodopsin is hit with photons and changes to all-trans isomer, and then the retinal-opsin combo breaks downs w/ help of enzymes
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excitation of cones happens when?
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in normal light -
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color blindness
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sex-linked recessive = more men have it - red-green is most common - from deficit of red-green cones
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transducin
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G protien that taken place in process that is normally inhibitory, but turns into an excitatory response (b/c ganglion cells generate action potentials)
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light adaption
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when we move from dark to light, bleaching is almost instant (b/c retina is still set for low light, but instantly responds
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dark adaption
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quick black out when moving into the dark - takes about 30 minutes to adjust fully b/c rods have been bleached by the previous light
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nyctalopia
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night blindness - from lack of Vit. A.
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retinosis pigmentosa
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rods are selectively destroyed- pigment epithelial cells are unable to recycle the tips of the rods as they get sloughed off
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primary visual cortex
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also called the striate cortex - in occipital lobe
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w/ a tramautic blow to the occipital lobe, what can happen?
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you can go blind
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chemoreceptors
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sensitive & respond to chemicals in aqueous solution
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olfactory receptive cells
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the more you have, the better your smell - shped like bowling pins
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filaments of the olefactory nerve
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slender, unmyelinated axons of the olefactory receptor cells gathered into smal fasicles
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german shepards can small ___times better than us
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20 X
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to smell, you need ___
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turbulence in your nose (sniffing)
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the olefactory pathway
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runs through the frontal lobe and connects to limbic system (Christmas buying sprees)
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what odors cause reflexive stopping of breathing?
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ammonia, strong chemical smells, etc
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whats special about taste buds?
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the only sense receptors made up of epithelium
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what are the 5 different tastes?
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sweet, sour, salty, bitter, umami
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umami
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cooked meat - on the back of the toungue (included MSG, and aspartate
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anosomias
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"without smells" when you can't smell - b/c of head injuries that tear olefactory nerves, aging, affter-effects of nasal cavity inflammation, or zinc deficiency
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uncinate fits
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olefactory hallucinations (rotting meat, etc) - olefactory auras happen for some epileptics
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auricle (or pinna)
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part of the outer ear - the elastic cartilage outside your head
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ceruminous glands
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produce cerumen / ear wax - excessive buildup can impair hearing
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tympanic membrane
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eardrum - boundry between the outer and middle ears - made of thin, translucent connectiuve tissue
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otitis media
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middle ear inflamation - common in kids - most common form of children's hearing loss - can be treated with anti-biotics
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myringotomy
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lancing of the eardrum 2 relieve pressure- implantation of a tiny tube that falls out within a year
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tensor tympani & stapedius mescles
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tighten to protect the 3 auditoruy ossicles in the middle ear - can't react quick enough to protect against axplosions = fractures in these bones = hearing loss/deafness
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name the 3 auditory ossicles
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1. malleus (hammer) 2. Incus (anvil) 3. stapes (stirrups)
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labyrinth
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another name for the middle ear
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mambranous labyrinth
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syeries of mambranous sacs & ducts contained in the bony labyrinth that follow its contours
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perilymph
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similar to CSF & continuous with it- conducts sounds vibrations involved in hearing and respond to mechanical forces during chages in body position & acceleration
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endolymph
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chemicall similar to intracellular fluid, but more K+ rich - conducts sounds vibrations involved in hearing and respond to mechanical forces during chages in body position & acceleration
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vestibule
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concerned with balance & proprioreception
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cochlea
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hearing organ - snail shaped - size of a split pea
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basically, how does process of hearing work?
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physical energy displacement is changed into electro-chemical impulses
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deafness
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hearing loss, no matter how slight
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2 types of deafness
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1. conduction deafness (something hampers sound conduction to the fluids of the internal ear) 2. sensoneural deafness (damage to neural structures)
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conduction deafness
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something hampers sound conduction to the fluids of the internal ear
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sensoneural deafness
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damage to the neural structures - due to stroke, tumor, or in-born problem
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tinnitus
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ringing or clicking sounds in the ear in the absence of auditory stimuli - similar to phantom limb pain
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meniere's syndrome
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Vertigo - standing erect is basically impossible - affects all 3 parts of the inner ear -
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otolithic membrane
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a jelly-like mass studded with tiny stones (otoliths)
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otoliths
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"ear stones" increase the otolithic membrane's weight & inertia
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crista ampullaris
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small elevation of the ampulla of each sami-circular canal- excited by head movement - specifically, rotational movement - fluid flows in opposite direction of movement
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