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52 Cards in this Set
- Front
- Back
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Two types of Sense Receptors
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General Receptors and Special Receptors
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General Receptors
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Receptors distributed throughtout the body
Sensory neurons ex) skin, organs |
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Special Receptors
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Receptor cells in localized areas
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How we get sensations?
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1) Stimulate a sense receptor
2) Conversion of the stimulus - energy created by stimuli converted to graded potential (electrical energy) 3) Generate of nerve impulse 4) Integration of sensory input (in cerebral cortex) |
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Sense Receptors - Location Classification
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-Exteroceptors
-Interoceptors -Proprioceptors |
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Exteroceptors
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external conditions stimuli
-located on or near surface of body |
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Interoceptors
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internal conditions stimuli
-located in visceral organs, blood vessals, muscles -not consciously felt |
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Proprioceptors
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located in muscles, joints, tendons, inner ear, nervous system
-body position, muscle tension, movement, weight discrimination |
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Sense Receptors-Stimulus Classification
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-mechanoreceptors
-thermoreceptors -nocireceptors -chemoreceptors -osmoreeptors -photoreceptors |
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Accessory structures of eye
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-eyelids
-eyebrows and eyelashes -lacrimal apparatus -extrinisc eye muscles |
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functions of eyelids
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shade, protect, lubricate
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orbicularis oculi & levator palpeebrae superioris
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closes/opens lid
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tarsal or meibomian glands
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-modified sebaceuous glands
-keep eyelids from adhering to eachother |
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conjunctiva
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-lines eyelids and attatched to white of the eye
-protective mucus membrane --vascular |
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lacrimal apparatus
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structures that produce and drain tears
-function protect clean lubricate the eyeball |
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Extrinsic eye muscle
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extend from bony orbit to sclera of eye
-surrounded by fat tissue |
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6 muscles that control eye movement
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superior rectus-up and in
inferior rectus-down and in medial rectus-inward lateral rectus-outward superior oblique-down and out inferior oblique-up and out |
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eyeball consists of three layers
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fribrous tunic-outer layer
vascular tunic-middle layer retina-inner layer |
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fibrous tunic composed of
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cornea, sclera,
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cornea
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transparent covering of iris
admits and refracts light into eye=helps focus light onto retina |
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sclera
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white of eye = dense connective tissue
provides shape to eyeball attachtment for eye mucsles |
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vascular tunic (uvea)=composed of
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choroid
ciliary body iris |
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choroid
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-lines sclera
-posterior portion of tunic -vascular -contains melanocytes - appears brown/black ---prevents reflection and scattering of light |
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ciliary body
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anterior portion of tunic
contains melanocytes (darkbrown appearance) Parts: ciliary processes and ciliary muscle |
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ciliary processes
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vascular folds of internal surface of ciliary body
---secretes aqueous humor |
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ciliary muscle
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circular band of smooth muscle
--muscle contraction changes the lens shape ---adapts for near or far vision |
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iris
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-colored portion of eyeball
attachted to ciliary processes mad eof melanocytes and smooth muscle fibers regulates amount of light into eyeball pupil=openng in center of iris |
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lens
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behind pupil and iris
contains protiens=crystallins lacks blood vessels helps focus images on retina |
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interior eyeball cavities
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anterior cavity and vitreuous chamebr
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anterior cavity
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filled w aqueous humor
---maintains shape of eyeball ----supplies oxygen and nutrients to lens and cornea |
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Vitreous chamber
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large cavity behind lens
---fillted w vitreous body -----jelly like substance -----maintain shape of eyeball -----keeps retina attached to choroid |
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retina
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inner layer of eyeball,
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retina consists of
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-pigmented layer=melanin
---help absorb light rays -neural (sensory layer) =processes visual data |
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three layers of neural layer
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-photoreceptors )rods and cones)
-bipolar cell layer -ganglion cell layer |
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macula lutea
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-on retina
-small flat spot-exact center posterior region of retina -visual axis of eye |
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macular degeneraion
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-degenerate disorder of retina; occur in region of macula lutea
---loose acute vision, but have peripheral vision |
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Fovea Centralis
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-on retina
-small depression in center of macula lutea -contains only cones area of highest resolution |
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optic disk
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-blind spot
-no rods or cones |
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photoreceptors of retina
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rods and cones
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rods
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enables to see in dim light
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cones
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-stimulated by bright light
-blue green red |
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Types of image formation
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-Refraction
-Accomodation -Contriction |
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Refraction
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bending of light rays
75% refraction through cornea 25% refraction through lens |
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accomodation
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change in shape of lens
depends on distance of object -dist object lens is flatter -close objects lens is more sphereical ciliary muscle controls lens shape |
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constriction
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narrowing of pupil
-circular muscles of iris control pupil diameter |
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Photopigments and vision
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-absorb light
-colored protein molecules -initiates events for nerve potentials -rods contains rhodopsin ---purplish color -cones contain three different types of pigments ---opsin=protein molecule ---retitnal=vitamen A derivative ------light absorbing part of photopigment |
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binocular vision
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both eyes focus on one set of objects
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nasal (central) half
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light rays from the nasal half will fall on the temporal half of the retina
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temporal (peripheral) half
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light rays from temporal half will fall on the nasal half of the retina
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nersightedness corrected w
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concave lens
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farsightedness corrected w
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convex lens
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astigmatism
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either cornea or lens has irregular curvature
get multiple focal points-parts of image s unfocused or distorted |
