Ch 3 - Vision

Question 1

The 3 layers of the eye

Answer 1

Outer layer = Fibrous
Middle layer = Vascular
Inner layer = Neural

Question 2

Components of the outer layer of eye

Answer 2

Cornea & it’s epithelium
Conjuctiva
Sclera

Question 3

Components of the middle layer of eye

Answer 3

Choroid

Iris

Question 4

Components of the inner layer of eye

Answer 4

Retina

Question 5

Blind Spot

Answer 5

Part of the retina
Anatomically called the optic disc which is the head of the optic nerve
It contains no receptors

Question 6

Macula

Answer 6

The central point of the retina

Has the highest visual acuity

Question 7

Fovea

Answer 7

Depression of macula where light is focused

Question 8

Rods

Answer 8

• low thresholds
• sensitive to low-intensity light
• low visual acuity (sharpness/clarity/distinctness) due to arrangement of many rods synapsing w/ bipolar cells
• increased in periphery of retina
• function well in darkness (black & white vision)

Question 9

Cones

Answer 9

• high threshold
• sensitive to high-intensity light
• high visual acuity due to arrangement of one cone to one bipolar cell
• increased in macula
• function well in daylight; color vision/photopic vision

Question 10

These cells are the final retinal link of the visual pathway

Answer 10

Ganglionic cells

Question 11

Outer Photoreceptors Segments

Answer 11

• contain rhodopsin which is a light-sensitive pigment
• rods contain stacks of free-floating double-membrane discs containing large amounts of rhodopsin
• cones contain cone-shaped in-foldings of surface membrane and have less rhodopsin
• the inner segment produces the photo pigment & the outer segment stores the photo pigment

Question 12

Inner Photoreceptors Segments

Answer 12

• contain mitochondria & other organelles
• synthesized rhodopsin
• the inner segment produces the photo pigment & the outer segment stores the photo pigment

Question 13

Do we SEE by excitation or inhibition?

Answer 13

Inhibition

Question 14

Visual Pathway from Optic Nerve

Answer 14

Optic Nerve -> Optic chiasm -> Optic tract

Optic nerve is before the crossing, chasm is where it crosses, tract is after the crossing

Question 15

Ipsilateral blindness

Answer 15

The lesion is on the same side as the blindness; occurs at the optic nerve

Question 16

Bitemporal hemanopia

Answer 16

The lesion is at the level of the optic chiasm. You lose temporal eye fields (the lateral/peripheral views) leaving you w/ tunnel vision

Question 17

Binasal hemanopia

Answer 17

You cannot see in the middle. You lose both nasal fields. Can only see in the periphery.

Question 18

Contralateral hemanopia

Answer 18

The lesion is in the optic tract & it effects the same sides of both eyes. Ex: if you lose blindness in left half of your left eye, your losing blindness in the left half of your right eye