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Anatomy & Physiology 207 > Special Senses: Vision Study Guide > Flashcards

Special Senses: Vision Study Guide Flashcards

1
Q

___% of the body’s sensory receptors are in the eyes.

A

70%

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2
Q

eyebrow function

A

Overlie the supraorbital margins; shade the eye from sunlight and prevent perspiration from reaching the eye

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3
Q

Eyelids (Palpebrae):

A

thin, skin-covered folds that protect the eye anteriorly

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4
Q

Palpebral Fissure:

A

separation between eyelids

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5
Q

Medial + Lateral Commissures

A

corners of the eyes

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6
Q

Lacrimal Caruncle

A

raised structure in medial commissure; oil + sweat glands

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7
Q

Tarsal Plates

A

supporting connective tissue for the eyelids; anchor points for orbicularis oculi and levator palpebrae superioris

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8
Q

Tarsal Glands

A

lubricating glands associated with the tarsal plates – when inflamed, causes a sty

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9
Q

Conjunctiva

A

transparent mucus membrane that produces a lubricating mucus secretion

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10
Q

Palpebral Conjunctiva:

A

membrane on the interior of the eyelids

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11
Q

Bulbar Conjunctiva

A

membrane that covers the white of the eyes – contains small blood vessels

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12
Q

Conjunctival Sac

A

space between the palpebral and bulbar conjunctiva – the area where a contact lens rests

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13
Q

tears

A

a dilute, saline solution containing mucus, antibodies, and lysozyme

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14
Q

What pathway do tears travel?

A

Blinking spreads tears toward the medial commissure, they enter the paired lacrimal canaliculi bia the lacrimal puncta. Tears drain into the lacrimal sac and the nasolacrimal ducts. Ducts enters the nasal cavity

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15
Q

6 extrinsic eye muscles + function

A
  • Lateral rectus: moves eye laterally
  • Medial rectus: moves eye medially
  • Superior rectus: elevates eye and turns it medially
  • Inferior rectus: depresses eye and turns it medially
  • Inferior oblique: elevates eye and turns it laterally
  • Superior oblique: depresses eye and turns it laterally
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16
Q

strabismus

A

Crossed eyes, misalignment of the eyes (one might deviate inwards/outwards)

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17
Q

2 humors of the eye

A

Aqueous humor in the anterior segment
Vitreous humor in the posterior segment

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18
Q

glaucoma cause

A

Build up of fluids will put pressure on the optic nerve and damage it, leading to vision problems

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19
Q

2 regions of the fibrous layer of the eye

A
  • Sclera: opaque posterior region
  • Cornea: transparent, anterior 1/6 of the fibrous layer
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20
Q

function of the sclera

A

Protects and shapes the eyeball
Anchors the extrinsic eye muscles
Posteriorly, where the optic nerve exits, the sclera is continuous with the dura mater of the brain

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21
Q

function of the cornea

A
  • Forms a clear window – allows light to enter, bends light
  • Both sides are covered with epithelium – the outer surface is protected from abrasions, the inner surface helps to maintain clarity
  • Contains many pain receptors – responsible for blinking and tearing reflexes
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22
Q

vascular layer of the eye is also called the

A

uvea

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23
Q

3 regions of the vascular layer

A

Choroid, ciliary body, iris

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24
Q

Choroid function

A

posterior portion of the uvea
- Supplies blood to all layers of the eyeball
- Brown pigment absorbs light to prevent scattering and visual confusion

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25
Q

ciliary body function

A

anterior portion
- Thickened ring of tissue surrounding the lens
- consists of ciliary muscles
- ciliary zonule
- capillaries of the ciliary processes

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26
Q

Iris

A

most anterior portion of the vascular layer
- colored part of the eye
- lies between the cornea and the lens – continuous with the ciliary body posteriorly
- pupil

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27
Q

ciliary muscles

A

in the ciliary body - smooth muscle bundles that control the shape of the lends

28
Q

ciliary processes

A

in the ciliary body - capillaries of these secrete fluid of the anterior segment of the eyeball

29
Q

ciliary zonule

A

(suspensory ligament) in the ciliary body - extends from the ciliary processes to the lens - holds the lens in position

30
Q

2 muscles that make up the iris

A

Sphincter pupillae and dilator pupillae

31
Q

how do the Sphincter pupillae and dilator pupillae
control the size of the pupil

A
  • For close vision and in bright light, sphincter pupillae contracts and the pupil constricts
  • Controlled by parasympathetic fibers!
  • For distant vision and in dim light, dilator pupillae contracts and the pupil dilates
  • Controlled by sympathetic fibers!
32
Q

where does the retina originate from?

A

an extension of the brain

33
Q

2 layers of the retina

A
  • outer layer: pigmented layer
  • inner layer: neural layer
34
Q

function of the pigmented layer of the retina

A

absorbs light/prevents scattering, phagocytizes photoreceptor cell fragments, and stores vitamin A

35
Q

3 types of neurons that make up the neuronal layer of the retina

A
  • photoreceptors
  • bipolar cells
  • ganglion cells
36
Q

How do signals pass between these different types of neurons in the retina?

A

Signals are produced in response to light and spread from the photoreceptors to the bipolar cells to the ganglion cells

37
Q

Which of these 3 types of neurons in the retina produces action potentials?

A

Ganglion cells

38
Q

do axons of the ganglion cells become …

A

the optic nerve

39
Q

optic disc

A

The site where the optic nerve leaves the eye

40
Q

why is the optic disc our blind spot

A

This site lacks photoreceptors so it is referred to as the blind spot

41
Q

About how many photoreceptors are in each retina?

A

Quarter billion photoreceptors

42
Q

What are the two varieties of photoreceptors

A

rods and cones

43
Q

rods

A

dim-light and peripheral vision receptors
- More sensitive to light than cones
- No color vision or sharp images
- Mostly located in the periphery of the retina

44
Q

Cones:

A

bright-light receptors
- Provide high-resolution, color vision

45
Q

Macula Lutea

A

oval region located lateral to the blind spot of each eye – contains mostly cones

46
Q

Fovea Centralis

A

tiny pit in the center of the macula lutea – contains all cones

47
Q

lens

A

A biconvex, transparent, flexible, and avascular structure

48
Q

location of lens

A

just posterior to the iris and held in place by the ciliary zonule

49
Q

function of lens

A

Changes its shape to precisely focus the light on the retina

50
Q

protein found in lens fibers

A

Crystallin

51
Q

Why does the lens become less elastic with age?

A

Lens fibers are continually added – the lens becomes more dense, more convex, and less elastic with age

52
Q

cataract

A

Clouding of the lens that causes visual distortion; can ge genetic or a result of diabetes mellitus or a result of various exposures

53
Q

refraction

A

Bending of light rays

54
Q

cause of refraction

A

when light passes from 1 transparent medium to another medium with a different density, the speed of light changes and refraction occurs

55
Q

pathway of light entering the eye

A

Cornea, aqueous humor, lens, vitreous humor, entire neural layer of the retina, photoreceptors

56
Q

Where is light refracted along the pathway of light entering the eye

A

Lights is refracted entering the cornea, entering the lens, and leaving the lens

57
Q

structure of the eye with the most refractory power

A

cornea

58
Q

structure of the eye that can accommodate

A

lens

59
Q

average far point for vision

A

about 20 feet for the healthy eye
(distance beyond which no change in lens shape (accommodation) is needed for focusing)

60
Q

average near point for vision

A

about 4 inches for the healthy eye

61
Q

shape the lens takes for distance vision

A

ciliary muscles are completely relaxed in distant vision – this causes pull on the ciliary zonule, and the lens is stretched flat

62
Q

shape the lens takes for close vision

A

parasympathetic input contracts the ciliary muscle. This loosens the ciliary zonule and allows the lens to bulge

63
Q

3 steps are required for effective close vision

A
  1. Accommodation of the Lens: changing the shape of the lens to increase refraction
  2. Constriction of the Pupils: prevents most divergent light rays from entering the eye – mediated by the parasympathetic system
  3. Convergence of the Eyeballs: medial rotation of the eyeballs causes convergence of the eyes towards the object being viewed
64
Q

presbyopia

A

loss of accommodation after age 50

65
Q

Myopia (nearsightedness)

A

eyeball is too long – the focal point is in front of the retina, a concave lens moves the focal point back – distance glasses

66
Q

Hyperopia (farsightedness):

A

eyeball is too short – the focal point is behind the retina, a convex lens moves the focal point forward – reading glasses

67
Q

astigmatism

A

unequal curvatures in different parts of the cornea or lens
Special glasses or laser surgery can correct

Anatomy & Physiology 207 (44 decks)

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