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Special Senses: Vision > Structure Of The Eyeball > Flashcards

Structure Of The Eyeball Flashcards

0
Q

The internal cavity is filled with what?

A

Fluid called Humors

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1
Q

What are the 3 layers the eyeball wall composed of?

A

Fibrous
Vascular
Sensory

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2
Q

What does the lens separate?

A

Separates the internal cavity into anterior & posterior segments

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3
Q

What is the fibrous layer composed of?

A

Two dense avascular connective tissue regions:

  1. Sclera
  2. Cornea
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4
Q

What is the Sclera?

A

White; opaque; tough

Protects & shapes the eyeball; anchors extrinsic muscles

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5
Q

What occurs at the optic nerve with the sclera?

A

Sclera becomes continuous with the dura mater

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6
Q

What is the cornea?

A

Transparent; anterior 1/6 of the fibrous layer

Cornea bends light as it enters the eye.

Numerous pain receptors contribute to blinking & tear reflexes.

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7
Q

What is the vascular layer?

A

The middle pigmented layer composed of three regions.

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8
Q

What are the 3 regions of the vascular layer?

A
  1. Choroid plexus
  2. Ciliary body
  3. Iris
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9
Q

Where is the choroid plexus?

A

Posterior portion of the Uvea.

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10
Q

What does the choroid plexus do?

A

Supplies blood to all the eye layers.

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11
Q

What does the choroid plexus contain?

A

Brown pigments that absorb light to prevent visual confusion that forms the posterior portion of the Uvea.

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12
Q

What is the ciliary body?

A

A thickened ring of tissue surrounding the lens.

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13
Q

What does the ciliary body contain?

A

Smooth muscle bundles (ciliary muscles) that controls lens shape.

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14
Q

What does the ciliary body do?

A

Anchors the suspensory ligaments that hold the lens in place.

Ciliary processes (of the ciliary muscles) contain capillaries that secrete fluid which forms the aqueous humor.

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15
Q

Where is aqueous humor made?

A

Ciliary processes

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16
Q

What is the Iris?

A

Pigmented portion of the anterior eyeball

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17
Q

What is the only pigment of the iris?

A

Brown

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18
Q

What does the Iris contain?

A

The pupil: the central opening of the iris that regulates the amount of light entering the eye

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19
Q

What two muscles control the pupil?

A
  1. Sphincter pupillae

2. Dilator pupillae

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20
Q

What happens when the muscles of the sphincter pupillae contract? What type of light is that for?

A

Contraction causes the pupil to constrict.

For Close vision & bright light.

21
Q

What happens when the muscles of the dilator pupillae contract? What type of light is that for?

A

Contraction causes pupil dilation.

For distant vision & dim light.

22
Q

What is the sensory layer of the eyeball?

A

The Retina: the innermost layer composed of a delicate 2-layer membrane.

23
Q

What are the 2 layers of the Retina?

A
  1. Pigmented layer

2. Neural layer

24
Q

What is the pigmented layer?

A

Outer layer that absorbed light and prevents its scattering.

25
Q

What layer stores Vitamin A?

A

Pigmented layer

26
Q

What layer contained melanin granules?

A

Pigmented layer

27
Q

What is the Neural layer?

A

Inner layer that covers the eyeball up to the Ora serrata (where it joins the ciliary body)

28
Q

What does the neural layer contain?

A

Contains Photoreceptors that transducer light energy (photons).

29
Q

What transmits signals and generates action potentials in the Neural layer?

A

Bipolar cells & ganglion cells

30
Q

Where are ganglion cell axons located?

A

Run along the inner surface of the retina, bundle together, and leave the as the optic nerve

31
Q

What is the site where the optic nerve leaves the eye known as?

A

Optic disc

32
Q

What is a blind spot?

A

It is the optic disc with no photoreceptors.

33
Q

What are the 2 types of photoreceptors?

A
  1. Rods

2. Cones

34
Q

Where are rods located?

A

Peripheral region of the retina

35
Q

What type of light to rods function in?

A

Dim light: provide indistinct, fuzzy, gray-scale peripheral vision.

36
Q

Where are Cones located?

A

Found in the Macuka lutea; concentrated in the FOVEA CENTRALIS

37
Q

What type of light do Cones function in?

A

Bright light, high-acuity color vision.

38
Q

What are the 2 sources of blood supply to the Retina?

A
  1. Choroid blood vessels (supply the outer 1/3)

2. Branches from the central artery & vein (supply the inner 2/3.

39
Q

What is diabetic retinopathy?

A

Damage to the retinal blood vessels secondary to diabetes mellitus.

40
Q

What is Macular Degeneration?

A

Damage to the central visual field with detachment of the retina

41
Q

What is the Inner Chambers of the eye?

A

The lens & suspensory ligaments divide the internal eye into anterior & posterior segments.

42
Q

What is the Posterior Segment of the inner chamber?

A

Contains the Vitreous humor; formed embryonically.

43
Q

What does the posterior segment do?

A
  • Transmits light
  • Supports the posterior surface of the lens
  • Holds the neural retina firmly against the pigmented layer
  • Contributes to intraocular pressure
44
Q

What is the anterior segment composed of?

A

Anterior chamber: between the cornea & iris

Posterior chamber: between the iris & lens

Aqueous humor

45
Q

What is the aqueous humor?

A

Plasma-like fluid, filtered continuously from capillary of the ciliary processes.

Drains continuously via the scleral venous sinus.

Supplies nutrients & oxygen to and removes wastes from the lens and cornea. (Also supplies the retina via diffusion)

46
Q

What is Glaucoma?

A

Abnormal increase in intraocular pressure due to blocked drainage (can damage retina & optic nerve).

47
Q

What is the Lens?

A

Bioconvex, transparent, flexible & avascular structure encased in an elastic capsule.

**changes shape to allow precise focusing of light onto the retina.

48
Q

What is the lens composed of?

A

Lens epithelium: anterior cuboidal cell, differentiate into lens fibers throughout life.

Lens fibers: cells filled with transparent proteins known as Crystallins.

49
Q

What happens to the lens with age?

A

Becomes more compact/dense & loses it’s elasticity.

50
Q

What is presbyopia?

A

Loses the ability to recoil to a round shape, thus loss of close vision.

51
Q

What is cataracts?

A

Clouding of lens: occurs due to aging, diabetes mellitus, heavy smoking, & frequent exposure to sunlight.

Special Senses: Vision (9 decks)

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