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2019 - Biology > the eye > Flashcards

the eye Flashcards

1
Q

receptors definition

A

specialized cells that detect stimuli and convert them into nerve impulses

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2
Q

photoreceptors

A

receptors which detect light stimuli

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3
Q

position of the eye

A

two eyes positioned in bony eye sockets at the front of the skull

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4
Q

eye structure

A
  • spherical ish and has six eye muscles which help w movement
  • front of eye is covered by conjunctiva
  • tear gland is above the eye
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5
Q

conjunctiva

A

thin mucous membrane which triggers a blink reflex when foreign objects enter the eye

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6
Q

things that protect the eye

A

eyelids, eyelashes

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7
Q

tear gland

A

secreted antiseptic tears that protect the conjunctiva from bacteria and dehydration

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8
Q

three layers of the eye

A

outer fibrous
middle vascular
inner light-sensitive retina

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9
Q

outer fibrous consists of

A

sclera

cornea

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10
Q

cornea

A

transparent part of the sclera, allows light rays through to the inner layers of the eye and refracts them

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11
Q

sclera

A

a strong white connective tissue that forms the outer layer of the eyeball
- protects internal parts, serves for muscle attachment

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12
Q

middle vasc layer consists of

A

choroid
ciliary body
iris
also: pupil; lens; susp ligaments

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13
Q

choroid

A

a thin, dark vascular layer

pigment absorbs excess light rays to prevent blurred images

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14
Q

ciliary body

A

a thickening of the front of the choroid, consisting of ciliary muscles and is attached to the lens by suspensory ligaments

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15
Q

ciliary body functions

A

contract and relax to change lens curvature during accomodation

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16
Q

iris

A
  • round structure in the middle of the eye

- at the front of the lens and contains pigments to give it color

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17
Q

pupil

A

opening in the middle of the iris through which light rays enter the eye

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18
Q

iris function

A

regulates the amount of light that enters the eye by controlling pupil size

19
Q

lens

A

rubbery elastic structure that changes shape

20
Q

lens function

A

changes shape to refract light rays and form an image on the retina

21
Q

inner-light sensitive retina consists of

A

pigment layer
nervous tissue layer
yellow spot
optic nerve

22
Q

pigment layer

A

outer layer that is in contact w choroid

pigment absorbs light rays, prevents internal reflection

23
Q

nervous tissue layer

A

consists of rods and cones which detect light stimuli (photoreceptors)

24
Q

rods

A

are stimulated in low light and give rise to b&w vision

25
Q

cones

A

stimulated in high light intensity and give rise to intense color vision

26
Q

yellow spot function

A

where the clearest most accurate image is formed

27
Q

function of optic nerve

A

conducts nerve impulses to the brain where they are interpreted to give sensation of sight

28
Q

divisions of the lens

A

anterior cavity

posterior cavity filled w vitreous humor (behind)

29
Q

anterior cavity

A

in front, aqueous humor
anterior chamber - betw cornea and iris
posterior - betw iris and lens

30
Q

vitreous humor functions

A
  • maintains eyeball shape
  • refracts light rays
  • hold retina in position
31
Q

what is the pupillary mechanism

A

reflex action which responds to the stimulus of the amount of light that enters the eye

32
Q

pupillary mechanism process

A 
BRIGHT LIGHT
radial musc relax (RR)
circular musc contract (CC)
pupil constricts
less light
vice versa for low light
33
Q

accommodation

A

the process during which the eye adapts for the observation of nearby objects (6m) by changing the lens shape

34
Q

accommodation for distant objects

A 
circular musc relax (CR)
ciliary body further away from lens
sus lig are taut (slacken)
lens less convex
less light refracted
sharp focused image on retina
35
Q

binocular vision

A

each eye forms its own image of the object, brain combines the two images to form a 3D image

36
Q

what binocular vision does

A

provides a wider field of vision and depth perception

37
Q

stereoscopic vision

A

the ability to see in 3D

38
Q

myopia

A
  • short sightedness

- elongated eyeball, cornea curve

39
Q

fixing myopia

A
  • concave lenses to diverge rays before they enter the eye

- laser surgery

40
Q

hypermetropia

A

shorter eyeball, flat cornea

41
Q

correcting hypermetropia

A

convex lenses, converges light rays to focus on the retina

laser surgery

42
Q

astigmatism

A

causes light rays to focus on more than one focal point

  • causes a blurry image
  • glasses, contacts, lasers
43
Q

cataracts

A

the clouding of the eyes lens, prevents light from reaching the retina, blurred vision
- initially glasses, or laser surgery

2019 - Biology (13 decks)

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