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Bio 30 > NS: Eye > Flashcards

NS: Eye Flashcards

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Biology 101 flashcards
1
Q

Parts of the outer eye and function

A
  • Eyelid (protection)
  • Orbital Cavity (support,
    protection)
  • Eyelashes (dust)
  • Lacrimal Ducts (tears, antibacterial)
  • Extrinsic Muscles (voluntary eye movement
  • Conjunctivia (transparent mucous membrane lining inner surface of eyelids, and fold back to cover front surface of eyeball)
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2
Q

Conjunctivitis

A
  • aka pink eye

- inflammation of conjunctivia caused by bacteria or allergies

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3
Q

Sclera

A
  • Dense white connective tissue
  • Outermost layer
  • Avascular (not a lot of blood)
  • Maintains shape
  • Cornea is a portion of sclera
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4
Q

Cornea

A
  • Clear portion of sclera
  • Covers front of eye
  • Focus and protect eye
  • aqueous humor (fluid behind cornea) supplies nourishment
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5
Q

Choroid Layer

A
  • Middle layer btwn sclera and retina
  • Vascular (nourishes retina)
  • Contains melanin to prevent light from scattering
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6
Q

Iris

A
  • Circular muscle (involuntary)
  • Controls amount of light entering eye (controls pupils, contracts and dilating)
  • Coloured
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7
Q

Pupil

A
  • Opening inside iris
  • Size depends on light intensity
  • Melanin: black pigment that makes pupil look black (from choroid layer, btwn sclera n retina)
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8
Q

Lens

A
  • Behind Iris
  • Transparent, biconcave, elastic, soft, avascular disc
  • Held in place by ciliary muscles
  • Changes shape to focus image onto back of retina
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9
Q

Retina

A
  • Innermost thin layer on back of eye cavity
  • Contains photoreceptors which converts light to nerve impulses
  • Lens focuses images on retina
  • has 4 layers: pigmented epithelium (prevents light from scattering), light sensitive cells, bipolar cells, cells of optic nerve
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10
Q

Eye cavities and functions

A
  1. Anterior eye cavity: “aqueous humor”, maintenance of shape, nourishment and focus
  2. Posterior eye cavity: “Virtreous humor”, Maintains shape of eyeball and permits light transmission to retina
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11
Q

Photoreceptors

A

-Two types of photoreceptors

  1. Rod: for light
  2. Cones:for colour
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12
Q

Rods

A

-Light sensitive cells on the periphery of the retina
-many rods per neuron
-18 million times as many rods as cones in the retina
-Detect low intensity light ( black and white and shades if grey) -> most effective at dusk and dawn (limited light)
contains a light sensitive pigment called rhodopsin
-For the rods to continue to work,rhodopsin levels must be maintained.
-vitamin A deficiency can permanently damage the rods

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13
Q

Rhodopsin

A
  1. Retinal (derivative of vitamin A)

2. Opsin protein

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14
Q

Cones

A

Cones are responsible for seeing colour
3 types of opsin proteins: sensitive to blue/green/red wavelengths of light (low light)
each type determines frequency of light able to be absorbed
high concentration of cones in the fovea centralis
fewer # than rods
1:1 ratio with neurons
100 cones : 1 ganglion

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15
Q

Fovea Centralis

A

Region with highest concentration of cones (detailed colour vision)
rods are around the fovea
depression in middle of retina

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16
Q

Order of Light Transmission

A
  1. light enter
  2. strikes retina (pigmented epithelium)
  3. rods, cones (sensory receptors on retina) > release neurotransmitters
  4. Bipolar cells
  5. Ganglion Cells > form optic nerve
  6. optic nerve > thalamus
  7. Occipital Lobe
17
Q

Ganglion cells

A

emphasize differences btwn images

18
Q

Horizontal cell

A

connect photoreceptors to bipolar cells

19
Q

Amacrine cells

A

Light adaptation and moving objects

20
Q

Pathway of focusing an image

A
  • when light enters the eye
  • light bent into pupil by cornea (light slows down when it enters the more dense media like cornea)
  • Cornea directs light inward towards the lens (further bending), ciliary muscles control the shape of the lens, suspensory ligaments (on lens) maintain tension
  • Inverted image is projected onto retina (light is directed at a focal point)
21
Q

Neural Pathway of light

A
  1. Optic Nerve
  2. Optic Chiasm
  3. Primary visual cortex: Occipital lobe of cerebrum
    l
  4. Visual association area
22
Q

What happens at Optic Nerve (Neural Pathway of Light)

A
  • All ganglion cells come together to form one optic nerve
  • Carries impulses to brain
  • Is the blind spot on retina (where optic nerves and vessels exist, there r no photoreceptors)
23
Q

Role of Optic Chiasm (neural pathway of light)

A
  • Nerves from both eyes come together and some cross to opposite sides of brain
  • Outside stays but inside crosses
  • Allows eyes to work as pair
24
Q

Primary visua cortex: Occipital lobe (neural pathway of light)

A
  • Receive info from optic nerves

- Does not interpret info

25
Q

Visual association area (neural pathway of light)

A
  • Interpretation of visual info

- turns image right side up n gives it meaning

26
Q

Accommodations for eyes

A
  • Adjustment made by lens and pupil for near and distant things
  • Increased age= decreased accommodation
  • Tendency of ppl needing glasses when older
  • Protein covering lens increase throughout whole life, make lens harder and less flexible
27
Q

Accommodation (for clarity of vision)

A
  • ciliary muscle and suspensory ligaments accommodate lens to focus light on retina
  • Near objects: ciliary muscles contract, lens thick and round, bends light for more clearer vision
  • Far objects: ciliary muscles relax, lens thinner and flatter
28
Q

Accommodations (light intensity)

A
  • changes diameter of pupil
  • near objects: pupil constricts to bring image into shape focus
  • far objets: pupils dilates to capture as much light possible into sharp focus
29
Q

Myopia

A
  • Nearsightedness
  • can see close but not far
  • eye too long, lens cannot flatten enough
  • image focused in front of retina
  • treatment: concave lens
30
Q

Hyperopia

A
  • Farsightedness
  • see far, not close
  • eye too short
  • lens too weak
  • image focused behind retina
  • treatment: convex lens
31
Q

Astigmatism

A
  • abnormal curvature of cornea/lens

- treatment: glasses

32
Q

Cataracts

A
  • cloudiness of cornea/lens due to lots of protein in lens

- treatment: corneal/lens transplant or strong contacts

33
Q

Glaucoma

A
  • high pressure in anterior cavity (aqueous humour) due to inability to drain regularly
  • damages cells in retina
  • leads to blindness
  • treatment: eyedrops or laser eye surgery
34
Q

Color blind

A
  • 1 or more cones defective
  • most common is red/green blindness
  • genetic and most common in males

Bio 30 (11 decks)

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