Vision System

Question 1

Half of the total brain mass is devoted to visual processing

Answer 1

holy shit

Question 2

Occipital cortex serves what function

Answer 2

Perception

Question 3

Visual memories stored where?

Answer 3

Parietal and Temporal Lobes

Question 4

Visual reflex

Answer 4

Brainstem and spinal cord

Question 5

Visual system provides information required for setting of the circadian rhythms, general metabolic rate, mood, etc…

Answer 5

These parts of vision occur in the pineal gland (circadian rhythm) and diencephalon

Question 6

HTN often diagnosed through analyses of the retina before blood pressure changes are noted by the patient

Answer 6

ok

Question 7

Functions of the sympathetic nervous system can be tested by pupil dilation

Answer 7

ok

Question 8

Fine focusing of incoming light is accomplished by

Answer 8

Fovea which is at teh center of the macula of the eye. Many animals do not have a macula or a fovea which is why their vision is not as crisp as ours.

Question 9

Lens refraction abilitites are controlled by

Answer 9

Cilliary muscles that are under sympathetic and parasympathetic nervous system control

Question 10

What is the sclera

Answer 10

a protective layer for the retina and choroid

Question 11

What is the choroid

Answer 11

The vascular bed of the outer retina

Question 12

Retinal blood flow is provided by

Answer 12

• Central Retinal Artery that enters through the optic nerves and supplies about 20% of the blood in the human retina.
• Choroid supplies the vast majority of blood to the retina

Question 13

Fovea is devoid of vessels

Answer 13

If vessels grow there it distorts the image

Question 14

Pigment cells in the retina are called what and serve what purpose

Answer 14

Retinal Pigmented Epithelial cells. They provide a barrier to the Retina from the choroid

Question 15

Photoreceptor cell bodies lie where

Answer 15

outer nuclear layer, their projections lie in the outer plexiform layer

Question 16

Retinal pathway

Answer 16

Photoreceptors (rods and cones) -> bipolar cells -> to ganglion cells

Question 17

What is the purpose of interneurons

Answer 17

They help in convergence of the image from the millions of photoreceptors to hundreds of bipolar cells to tens of ganglion cells.

Question 18

Interneurons located where

Answer 18

Outer plexiform layer (horizontal cells)

Inner plexiform layer (amacrines)

Question 19

Ganglion cell axons coalesce to do what

Answer 19

Form optic nerve head.

Question 20

Where is the blind spot

Answer 20

Optic nerve entry into the retina

Question 21

RPE main function

Answer 21

separate vascular choroid from neural retina

Question 22

Macular degeneration results when….

Answer 22

blood vessels damage the RPE and break through their barrier to the macular region of the eye. This causes visual distortion of the image

Question 23

What is the other main function of the RPE

Answer 23

To eat outer rod segments every 10 days. As we age, this becomes less effective. Proteins are left in the RPE and they can autoflouresce. This is called Drusen which is a key factor of macular degeneration

Question 24

Melanin in the RPE does what

Answer 24

absorbs some of the light that comes to the photoreceptors

Question 25

Rods are responsible for

Answer 25

black and white vision

Question 26

Light transduction occurs in what segment of rods

Answer 26

outer segment

Question 27

KNOW that the outermost outer segment of rods is phagocytosed by the RPE cell layer every 10 days. A new outer segment extends from the inner segment and joins up with the other segments.

Answer 27

ok

Question 28

Cones are responsible for

Answer 28

color vision

Question 29

3 types of cones

Answer 29

L- long wavelenghts M- Medium wavelengths S- Shorter wavelengths

Question 30

M and L cones are carried on what chromosome

Answer 30

X...thats why men are more likely to be colorblind, because they have only 1 x chromosome.

Question 31

L cones

Answer 31

red

Question 32

M cones

Answer 32

green

Question 33

S cones

Answer 33

blue

Question 34

Vision occurs when rods and cones........ to light

Answer 34

hyperpolarize!!! This is the only sensory system where hyperpolarization is the key response to light

Question 35

KNOW slide 15

Answer 35

ok...Most important slide of presentation

Question 36

Once photoreceptors have processed the light, signal is passed to what

Answer 36

Bipolar cels

Question 37

Rod Photoreceptors transduce their signal to rod bipolar cells and cone photoreceptors transduce their signal to

Answer 37

Cone bipolar cells

Question 38

What cell types help to converge the signal from a bunch of rod photoreceptors to fewer rod bipolar cells

Answer 38

horizontal cells

Question 39

Ganglion cells

Answer 39

There are different types. They activate based on image and project to different regions of the brain

Question 40

Alpha ganglion cells

Answer 40

Most from rods.Teir job is to help locate the object in space. Project to magnocellular layer of LGN

Question 41

Beta ganglion cells

Answer 41

Found Primarily in central retina. Define color and texture. Respond predominantly to cones. Project to Parvocellular region of LAG

Question 42

What alows for crisp image representation

Answer 42

in teh fovea there is 1 photoreceptor/1 ganglion cell NO CONVERGENCE!!!

Question 43

Left visual field is processed where

Answer 43

Right visual cortex

Question 44

So we know that images are inverted and shrunk once they cross through the eye. What is it about the eye that causes the image to shrink

Answer 44

Refracted by the LENS and CORNEA

Question 45

Lens refraction is under control of what?

Answer 45

Ciliary muscles

Question 46

Note that convergence does not occur in the fovea!!! One photoreceptor supplies one ganglion cell

Answer 46

This is why the image is crisp.

Question 47

WHich fibers cross in the optic chiasm

Answer 47

only the nasal fibers

Question 48

Once passing through the optic chiasm, where do fibers move?

Answer 48

Into the Lateral Geniculate ganglion and into the visual cortex

Question 49

Diabetic retinopathy

Answer 49

changes in vasculature (GF) | Changes in

Question 50

Dry macular degen vs wet

Answer 50

Dry: LIttle vision loss in one eye usually. 90% of cases Wet: blood vessels grow into macula and cause significant visual loss...both eyes