Retina

Question 1

What is the nervous coat of the orbit called?

Answer 1

Retina

Question 2

What must light pass through to reach retina? 4

Answer 2

cornea, aqueous humor, lense, vitreous body

Question 3

What is the fovea centralis?

Answer 3

central point of retina with only cones

Question 4

What does the abundance of cones in fovea do?

Answer 4

gives high level of visual aquity

Question 5

Maculua lutea

Answer 5

Yellow area surrounding fovea

Question 6

what gives maculua lutea its yellow color?

Answer 6

Accumulation of lutein and zeaxanthin, carotenoids

Question 7

what do the carotinoids of the maculea do?

Answer 7

antioxidant activity, absorb excess blue/ultraviolet light.

Question 8

why is there a blind spot?

Answer 8

The optic dist is where axons and central artery exit the orbit, there are no receptors.

Question 9

What supplies blood to retina?

Answer 9

Brance of internal carotid, the central artery.

Question 10

What surface of retina does central artery exit onto?

Answer 10

Central artery exits onto the inner surface of retina

Question 11

What are the 4 retinal layers?

Answer 11

RPE retinal pigmented epithelium, Photo receptors, neural cells and ganglion cells

Question 12

What do photo receptors do?

Answer 12

absorb visible light

Question 13

What do neural cells due?

Answer 13

they integrate light information,

Question 14

What form are neural cells?

Answer 14

bipolar, (horizontal and amarcrine)

Question 15

Job of ganglion cells?

Answer 15

project visual information to thalamus, superior colliculus and more, their axon leaves the eye

Question 16

What does the outer layer of rods and cones contain?

Answer 16

stacks of pigmented disks.

Question 17

Pigmented disks in rods?

Answer 17

rhodopsin

Question 18

Pigmented disks in cones?

Answer 18

iodopsin

Question 19

what does the inner segment of photoreceptors, the part with the nucleus contain?

Answer 19

synaptic terminal that releases glutamate

Question 20

Visable light is part of whats frequency spectrum

Answer 20

electromagnetic radiation

Question 21

where are the pigments in photoreceptors located?

Answer 21

inside vescular disks on the terminal end

Question 22

What spectrum of visable light do pigments respond to?

Answer 22

450 - 700 nm

Question 23

What happens to photo receptor upon exposure to light?

Answer 23

Hyperpolarization that inhibits release of glutamate

Question 24

What channels close to hyperpolarize cell?

Answer 24

Na and Ca++

Question 25

what type of messenger signal closes the channels to cause hyperpolarization?

Answer 25

Opsin activates Phosphodiesterase PDE via a transducen

Question 26

What type of messenger is transducen?

Answer 26

G protein

Question 27

Light converts retinal how?

Answer 27

from cis retinal to trans retinol

Question 28

Photopic

Answer 28

vision in bright light, low sensitivity

Question 29

Scotopic

Answer 29

vision in dim ligh, highly sensitivity, night vision

Question 30

What receptor is photopic?

Answer 30

cones, best in bright light

Question 31

What receptor is scotopic?

Answer 31

rods, good for ight vision

Question 32

What receptor gives the best acuity?

Answer 32

cones, because they are concentrated in fovea

Question 33

what gives best spacial resolution, ie acuity?

Answer 33

cones

Question 34

What receptor is achromatic?

Answer 34

cones,, color vision through 3 pigmented cells.

Question 35

What receptors are more sensitive to scattered light?

Answer 35

rods, good for ight vision

Question 36

What receptor is better at detecting visual motion?

Answer 36

rods.

Question 37

Where are cones in the retina?

Answer 37

everywhere but they are most abundant in the fovea

Question 38

Where are rods in the retina?

Answer 38

The are not in the fovea but are extreamly abundant everywhere else.

Question 39

Why would the fovea have the most cones?

Answer 39

because it is the center of the visual field. So wants the best visual aquity

Question 40

How are cells arranged in the fovea?

Answer 40

The shallower cells, the ganglion and bipolar cells are pressed away to the side allowing light more direct acess to the cones for increased acuity

Question 41

Why is it good that the photo receptors are so deep in the retina?

Answer 41

IT puts them closest to the choroid body

Question 42

Why do rods and cones need to be near blood supply, choroid body?

Answer 42

because pigment turnover requires lots of oxygen

Question 43

How does light get past the ganglion and bipolar cells?

Answer 43

light passes through them, they refract just like aqueous humor

Question 44

What is the layer deep to the photoreceptors?

Answer 44

retinal pigment epithelium RPE

Question 45

What are the 5 jobs of the RPE?

Answer 45

Visual acuity, antioxidant, maintain photoreceptor excitability, nutrients provider, phagocytosis of cell debries

Question 46

How does RPE effect visual acuity?

Answer 46

limits reflection of light back to receptors after the first pass, prevents blurred image

Question 47

Why would RPE absorbe blue light?

Answer 47

blue light increases free radical formation in retinal cells

Question 48

what brings retinol to photoreceptors?

Answer 48

RPE retinal pigmented epithelium, Photo receptors, neural cells and ganglion cells

Question 49

what would deficient uptake of membrane fragments cause?

Answer 49

separation of receptors from choroid.

Question 50

if receptors separate from RPE, what would happen?

Answer 50

anoxia and cell death

Question 51

why is fovea avascular?

Answer 51

improved acuity without vascular interference

Question 52

how does waste and water get transported from extracellular space at fovea to choroid?

Answer 52

Membrain transporters in the RPE

Question 53

Why is retinal detachment relatively easy?

Answer 53

Attachment of REP to photoreceptors is unstable, there is nothing physically keeping them together.

Question 54

What can cause retinal detachment, 2?

Answer 54

Buildup of cellular waste under the retina or leaking blood vessels under RPE

Question 55

What is detached retina called?

Answer 55

macular degeneration

Question 56

What does optic nerve consist of? 3

Answer 56

Axons of ganglion cells, GLIAL cells, central artery and vein

Question 57

Why should optic nerve be called tract?

Answer 57

Because it has menegies just like the CNS

Question 58

What type of CNS glia does optic nerve have?

Answer 58

Oligodendrocytes and astrocytes

Question 59

oligodendrocytes do what?

Answer 59

myleinate axons

Question 60

astrocytes do what?

Answer 60

surround cell bodies and dendrites, and also contract blood vessels.

Question 61

Papilledema

Answer 61

increased CSF pressure that limits venous return from retina causing edema under optic disc.

Question 62

how to idea papilledema?

Answer 62

blurred disk margin when viewed with opthalmoscope

Question 63

What does papilledema do in additon to edema under optic disk?

Answer 63

Expaned CSF space around CN II, More veins in eye, axoplasmic stasis of ganglion cells.

Question 64

why do we not notice our blind spot?

Answer 64

binocular vision, info within blind spot is interpolated from adjacent areas of retina during eye movements or by visual cerebral cortex activty.