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28 Cards in this Set
- Front
- Back
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Sense organ use
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Detect stimuli.
They are groups of receptor cells that respond to specific stimuli |
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Organ- stimulus
Eye- Nose- Tongue- Ears- Skin- |
Light
Chemicals in air Chemicals in food Sound vibrations. Also detects movement and position of body so provides info on balance |
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Eye structure
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Tbc
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Light enters eye through
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Cornea
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Pupil is
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Hole in the eye
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Retina has
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Light sensitive receptor cells
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Conjunctiva
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Delicate transparent layer which provides protection
Kept moist by tear gland |
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Tears contain..which kills bacteria
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Lysozyme
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Role of iris and pupil
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Regulate intensity of light that reaches retina
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Pupil reflex
Dim light |
Circular muscles relax
Radial muscles contract Pupil dilates |
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Pupil reflex
Bright light |
Circular muscles
Radial muscles relax Pupil constricts |
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Ciliary muscle
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Chances thickness of lens when focusing
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Choroid
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Full of black pigment to absorb light and stop reflection
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Vitreous humor
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Jelly like substance which maintains the internal pressure in eye and its shape
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Retina
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Inner light sensitive layer which contains rods and cones
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Fovea or yellow spot
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Most sensitive part of retina
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Blind spot
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Where optic nerve attaches to eye
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Aqueous humor
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Watery liquid filling front of eye
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Lens
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Changes shape to focus light in retina
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Iris
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Control intensity of light entering through pupil
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Suspensory ligament
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Holds lens in place
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Sclerotic
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Tough white protective layer
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Rods
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Responsible for night vision
Respond to low intensity light Around periphery of retina |
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Cones
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Responsible for colour vision and respond to light of high intensity
Most in fovea |
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In the retina...
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Light stimulates rods and cones
Impulses sent to brain along optic nerve Brain interprets impulses to form picture Image is upside down but brain interprets right side up |
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Accomodation
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Changes that occur in eye when focusing on far and near objects
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Accommodation
Distant objects |
Ciliary muscles relax
Pressure inside eye pulls s.ligaments taut so lens is pulled into an elliptical (thin) shape |
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Near object
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Ciliary muscles contract
S.ligaments become slack so elastic tissue around lens recoils so lens becomes more spherical(fatter) Rays are refracted more than when distant object |
