3.3.1 Vision II

Question 1

What are the covered parts?

Answer 1

Question 2

What is the pathway of aqueous humor flow?

Answer 2

Ciliary body → posterior chamber → pupil → anterior chamber → Canal of Schlem

Question 3

What allows for contraction and dilation of the pupil?

Answer 3

An inner sphincter muscle - constricts the pupil

Outer radial muscle - dilates the pupil

Question 4

Describe the beginning of signal processing in the retina?

Answer 4

Photoreceptors transduce photons into neuronal activity and synapthic processing begins in the retina.

Ganglionic cell axons will travel to the thalmus

Question 5

What are the covered parts?

Answer 5

Question 6

Where must light be focused to initiate processing of visual signals?

Answer 6

Light must be focused precisely on the neural retina

Question 7

What are the two locations in the eye at which light is refracted?

Answer 7

Cornea - static refraction

Lens - dynamic refraction

Question 8

What is the difference between a hyperopic eye and a mypoic eye?

Answer 8

Hyperopic eyes tend to have a focal length that is behind the retina in space, thus making them “far-sighted”

Myopic eyes tend to have a focal length that is located in front of the retina, thus making them “near-sighted”

Question 9

What is presbyopia?

Answer 9

Lens of the eye hardens making it resistance to changes in shape

Question 10

How is a map of the external environment created on each retina?

Answer 10

Question 11

Humans have binocular vison, what does this mean?

Answer 11

Both eyes can focus on a single space - unlike a fish

Question 12

Vision from the left side of the visual field is interpreted where? Right side?

Answer 12

Question 13

Structures distal to the optic chiasm contain a retina map of?

Answer 13

The contralateral visual field with contributions from both eyes for binocular regions

Question 14

Visual fields outside the binocular region must be?

Answer 14

Decussate to reach the contralateral side of the brain

Question 15

What is the process by which visual transduction occurs in photoreceptor outer segements?

Answer 15

Question 16

After absorption of a photon and shifting to all-trans retinAl, what happens in the visual signal transduction pathway?

Answer 16

Light stimulation will close Na channels leading to hyperpolarization of the photoreceptor membrane. This will then reduce glutamate release.

Question 17

Describe the levels of glutamate released by photoreceptor rods in the dark vs in the light?

Answer 17

Dark - high amounts of glutamate

Light - low amounts of glutamate is releases

Question 18

Describe the properties of the photoreceptor rods.

Answer 18

Operates in dim light, and can detect a single photon of light

Many rods, many bipolars, one ganglion - meaning low acuity

Sacrifices acuity to gain sensitivity

Found in periphery of retina

Question 19

Describe the properties of photoreceptor in the cone system.

Answer 19

Operates in bright light

Few cones, one bipolar cells, and one ganglion cell - maximum acuity

High density in the fovea

Different opsins sensitive to different wavelengths of light.

Question 20

Describe the different layers of this image.

Answer 20

Throwing you a curve ball! Figure this one out on our own. Look at the image from earlier in the slides and determine what layers correspond to which :)

Question 21

Presense of any exogeneous substance (ex. blood) in the vitreous humor can do what?

Answer 21

reduce visual acutiy or may result in blind spots

Question 22

Optic nerve fibers are myelinated by?

Answer 22

Oligodendrocytes

And are bathed in CSF

Question 23

Inner retinal layer have blood supplied by?

Answer 23

Branches of the central retinal artery

Question 24

During development what supplies blood to the photoreceptors?

Answer 24

Retinal pigment epithelium

Question 25

Describe the distribution of rods and cones throughout the eye.

Answer 25

Question 26

How are visual signals processed into visual pathways?

Answer 26

With the retina, bipolar and ganglion cells are tuned to detect contrast.

Neurons at each level of the pathway have receptive fields defined by location and complexity.

Receptive fields become more complex as one moves to higher centers of the pathway.