Visual System

Question 1

Percentage of body’s sensory receptors in eye?

Answer 1

70%

Question 2

How much of the brain processes visual information

Answer 2

About half

Question 3

What protects the eye?

Answer 3

• Cushion of fat

- Bone

Question 4

Accessory structures of the eye

Answer 4

• Eyebrows
• Eyelids (palpebrae)
• Conjunctiva
• Lacrimal apparatus
• Extrinsic eye muscles

Question 5

Eyebrows and eyelid

Answer 5

• Overlie supraorbital margins
• Shades eye from sunlight
• Prevents sweat from reaching eye

Question 6

Levator palpebrae superioris

Answer 6

Upper eyelid mobility

Question 7

How often do people blink?

Answer 7

Every 3-7 seconds

Question 8

Why do we blink?

Answer 8

Protect the eye and spread secretions to moisten eye

Question 9

Conjunctiva

Answer 9

• Transparent mucous membrane

- Produces a lubricating mucous secretion

Question 10

Palpebral conjunctiva

Answer 10

Lines eyelids

Question 11

Bulbar conjunctiva

Answer 11

Covers white of eyes

Question 12

Conjunctival sac

Answer 12

• Between palpebral and bulbar conjunctiva

- Where contact lens rest

Question 13

Conjunctivitis

Answer 13

• Pinkeye

- Can be caused by adenovirus, viral infections

Question 14

Lateral rectus

Answer 14

• Action: Moves eye laterally

- Cranial nerve: VI (abducens)

Question 15

Medial rectus

Answer 15

• Action: Moves eye medially

- Cranial nerve: III (oculomotor)

Question 16

Superior rectus

Answer 16

• Action: Elevates eye and turns it medially

- Cranial nerve: III (oculomotor)

Question 17

Inferior rectus

Answer 17

• Action: Depresses eye and turns it medially

- Cranial nerve: III (oculomotor)

Question 18

Inferior oblique

Answer 18

• Action: Elevates eye and turns it laterally

- Cranial nerve: III (ovulomotor)

Question 19

Superior oblique

Answer 19

• Action: Depresses eye and turn it latterally

- Cranial nerve: IV (trochlear)

Question 20

Layers of eyeball wall

Answer 20

• Fibrous
• Vascular
• Inner

Question 21

Fluid filling eye’s internal cavity

Answer 21

Humor

Question 22

Iris muscles

Answer 22

• Sphincter pupillae

- Dilator pupillae

Question 23

Response to parasympathetic stimuli

Answer 23

• Sphincter pupillae muscle contracts

- Pupil size decreases

Question 24

Response to sympathetic stimuli

Answer 24

• Dilator pupillae muscle contracts

- Pupil size increases

Question 25

Optic disc

Answer 25

- Blind spot - Site where optic nerve leaves eye - Lacks photoreceptors

Question 26

Types of photoreceptors

Answer 26

- Rods | - Cones

Question 27

Characteristics of rods

Answer 27

- Noncolor vision (one visual pigment) - High sensitivity; functions in dim light - Low acuity (many rods converge onto one ganglion cell) - More numerous (20 rods /er cone) - Mostly in peripheral retina

Question 28

Characteristics of cones

Answer 28

- Color vision (three visual pigments) - Low sensitivity; functions in bright light - High acuity (one cone per ganglion cell in fovea) - Less numerous - Mostly in central retina

Question 29

Myopic eye

Answer 29

- Nearsighted: can see near but not far - Uncorrected: focal point is in front of retina - Corrected: concave lens moves focal point further back

Question 30

Hyperopic eye

Answer 30

- Farsighted: can see far but not near - Uncorrected: focal point is behind retina - Corrected: convex lens moves focal point forward

Question 31

What happens if there is an injury to the optic chiasma?

Answer 31

- Damage to this area will cause possible damage to the temporal field in both Rt and Lt eye - Will not see from the sides peripheral

Question 32

What happens if there is an injury to the optic tract?

Answer 32

- Damage to this area will cause possible damage to the temporal filed of the Rt eye and possible damage to the nasal field of the Lt eye. - Will not see from the side (peripheral vision) in Rt eye. - Will not see what is in front from the Lt eye

Question 33

What happens if there is an injury to the primary visual cortex?

Answer 33

- Damage to this area will cause possible damage to the temporal filed of the Lt eye and possible damage the nasal field of the Rt eye - Will not see from the side (peripheral vision) in Lt eye. - Will not see what is in front from the Rt eye.