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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
ciliary body function
anterior portion - Thickened ring of tissue surrounding the lens - consists of ciliary muscles - ciliary zonule - capillaries of the ciliary processes
26
Iris
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
27
ciliary muscles
in the ciliary body - smooth muscle bundles that control the shape of the lends
28
ciliary processes
in the ciliary body - capillaries of these secrete fluid of the anterior segment of the eyeball
29
ciliary zonule
(suspensory ligament) in the ciliary body - extends from the ciliary processes to the lens - holds the lens in position
30
2 muscles that make up the iris
Sphincter pupillae and dilator pupillae
31
how do the Sphincter pupillae and dilator pupillae control the size of the pupil
- 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
where does the retina originate from?
an extension of the brain
33
2 layers of the retina
- outer layer: pigmented layer - inner layer: neural layer
34
function of the pigmented layer of the retina
absorbs light/prevents scattering, phagocytizes photoreceptor cell fragments, and stores vitamin A
35
3 types of neurons that make up the neuronal layer of the retina
- photoreceptors - bipolar cells - ganglion cells
36
How do signals pass between these different types of neurons in the retina?
Signals are produced in response to light and spread from the photoreceptors to the bipolar cells to the ganglion cells
37
Which of these 3 types of neurons in the retina produces action potentials?
Ganglion cells
38
do axons of the ganglion cells become ...
the optic nerve
39
optic disc
The site where the optic nerve leaves the eye
40
why is the optic disc our blind spot
This site lacks photoreceptors so it is referred to as the blind spot
41
About how many photoreceptors are in each retina?
Quarter billion photoreceptors
42
What are the two varieties of photoreceptors
rods and cones
43
rods
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
Cones:
bright-light receptors - Provide high-resolution, color vision
45
Macula Lutea
oval region located lateral to the blind spot of each eye – contains mostly cones
46
Fovea Centralis
tiny pit in the center of the macula lutea – contains all cones
47
lens
A biconvex, transparent, flexible, and avascular structure
48
location of lens
just posterior to the iris and held in place by the ciliary zonule
49
function of lens
Changes its shape to precisely focus the light on the retina
50
protein found in lens fibers
Crystallin
51
Why does the lens become less elastic with age?
Lens fibers are continually added – the lens becomes more dense, more convex, and less elastic with age
52
cataract
Clouding of the lens that causes visual distortion; can ge genetic or a result of diabetes mellitus or a result of various exposures
53
refraction
Bending of light rays
54
cause of refraction
when light passes from 1 transparent medium to another medium with a different density, the speed of light changes and refraction occurs
55
pathway of light entering the eye
Cornea, aqueous humor, lens, vitreous humor, entire neural layer of the retina, photoreceptors
56
Where is light refracted along the pathway of light entering the eye
Lights is refracted entering the cornea, entering the lens, and leaving the lens
57
structure of the eye with the most refractory power
cornea
58
structure of the eye that can accommodate
lens
59
average far point for vision
about 20 feet for the healthy eye (distance beyond which no change in lens shape (accommodation) is needed for focusing)
60
average near point for vision
about 4 inches for the healthy eye
61
shape the lens takes for distance vision
ciliary muscles are completely relaxed in distant vision – this causes pull on the ciliary zonule, and the lens is stretched flat
62
shape the lens takes for close vision
parasympathetic input contracts the ciliary muscle. This loosens the ciliary zonule and allows the lens to bulge
63
3 steps are required for effective close vision
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
presbyopia
loss of accommodation after age 50
65
Myopia (nearsightedness)
eyeball is too long – the focal point is in front of the retina, a concave lens moves the focal point back – distance glasses
66
Hyperopia (farsightedness):
eyeball is too short – the focal point is behind the retina, a convex lens moves the focal point forward – reading glasses
67
astigmatism
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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