Special senses study guide – Flashcards
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Sensory receptors
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Structures which are stimulated by changes in enviroment
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What is the sclera?
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The outer layer or white of the eye
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What does the sclera do?
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Maintain shape of eye and protects structures within
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Extrinsic muscles
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Muscles responsible for moving the eye within the orbital socket attached to the outside of the sclera
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What is the cornea?
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Located in the very front center of the sclerotic coat; circular clear area
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What is also know as the window of the eye?
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Cornea
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What does the cornea do?
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Transparent to permit the passage of light rays
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What is the middle payer of the eye?
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Choroid coat
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What does the choroid coat do?
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Contains blood vessels to nourish the eye and a no reflective pigment rendering it's dark and opaque
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What is in the front of the choroid coat that is a circular opening?
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Pupil
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What is the colored, muscular layer surrounding the pupil?
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Iris
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What are intrinsic muscles?
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Two sets of smooth muscle, the sphincter and the dilator papillae
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What do the intrinsic muscles help the iris do?
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To control amounts of light entering the pupil
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What does the pupil when the eye focuses on a close object or stimulated by bright light?
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Contract
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What does the pupil do when focused on a distant object or dim light?
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Dilate
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What are the lens?
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A crystalline structure located behind the iris and pupil
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What is the purpose of the lens?
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To focus images on the retina
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What is accommodation?
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When the muscle controls the shape of the lens for vision at near and far distances
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What are the lens situated between?
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Anterior and posterior chambers
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What watery liquid is the anterior chamber filled with?
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Aqueous humor
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What does the aqueous humor do?
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It constantly replenishes by blood vessels behind the iris
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What is the vitreous humor?
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A transparent jellylike substance, which fills the posterior chamber
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What do both substances help maintain?
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The eyeballs spherical shape, refracting(bending) light rays as they pass through the eye
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What is the inner most or third layer of the eye?
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Retina
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Where is the retina located?
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Between the posterior chamber and choroid coat
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What pigment and specialized cells does the retina contain?
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Rods and cones
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What are the rod cells are sensitive to?
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Dim light
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What are the cones sensitive to?
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Bright light
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What are cones responsible for?
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Color vision
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What is the pale disc slightly to the side of the fovea?
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Optic disc and blind spot
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What gathers at the optic disc?
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Nerve fibers
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Does the optic disc contain rods and cones?
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NO
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What is the pathway of vision?
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Image,cornea, pupil, lens, retina, rods and cones, optic nerve, optic chiasma, optic tracts, occipital lobe
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What is conjunctivitis?
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Inflammation of the conjunctival membranes, also known as pink eye
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What is glaucoma?
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A condition of excessive intraocular pressure resulting in the destruction of the retina and atrophy of the optic nerve
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What does glaucoma result from?
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Overproduction of the aqueous humor
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What are cataracts?
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A condition where the lens of the eye gradually become cloudy
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What is macular degeneration?
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Eye disorder that occurs as a person ages, in the central part of the retina the macula degenerates which is responsible for sharp vision
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What happens when a retina is detached?
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The vitreous fluid contracts as it ages and pulls on the retina causing it to tear
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What is diabetic retinopathy?
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Leading cause of blindness and is caused by changes in blood vessels on the retina
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What is a sty (hordeolum)
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A tiny abscess at the base of an eyelash
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What is color blindness?
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The inability to distinguish colors
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What is strabismus?
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Cross-eyes
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What is diplopia?
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Blurred vision
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What is an astigmatism?
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Irregular curvature of the cornea or lens
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What is the organ of corti?
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The receptors of hearing within the cochlea of the inner ear
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What is the pinna?
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The outer ear
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What does the pinna do?
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Collects sound waves and directs them into the auditory canal
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What is the auditory canal lines with?
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Ceruminous glands
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What is cerumen?
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Ear wax
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What does cerumen do?
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Protects the ear
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What is the tympanic membrane?
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Ear drum
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What does the ear drum do?
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Separates the outer and middle ear
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What does the tube that connects the middles ear and throat?
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Eustachian tube
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What does the Eustachian tube serve as?
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To equalize the air pressure in the middle ear
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What bones are found on the middle ear?
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Hammer(malleus), anvil(incus),sirrup(stirrup)
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What do the bones do?
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Transmit sound waves from ear drum to inner ear
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What is the special organ of hearing that is spiral shaped?
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Cochlea
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What does the cochlea contain?
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A membraneous tube called the cochlear duct
