Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Ocular anatomy > Retina > Flashcards

Retina Flashcards

1
Q

What is the location of the retina

A

from ora serrata to the optic nerve head or disc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does the retina contain

A

light sensitve receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the function of the retina

A

Convert electromagnetic energy in the retinal image into neural signals

Neural signals ar then gathered to be transmiteed out of the ye thoruhg the optic nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the fovea

A

The dark spot at the back of the eye that allows the sharpes vision

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the ten layers in the retina, from closes to the sclera

A

Retinal pigment epitherlium

Photoreceptor layer

External (outer) limiting membrane

Outer nuclear layer

Outer plexiform layer

Inner nuclear layer

Inner plexiform layer

Ganglion cell layer

Nerve fibre layer

Inner limting membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where is the RPE located

A

Single layer of cuboidal cells extending from ora serrata to optic nerve head

Anterior continous with the pigmented epithelium of ciliary body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the function of the RPE

A

Protects the photoreceptors from excessive light

Supports the receptors
- provides receptors with a pathway of nourishment and oxygen from the choriocapillaries
-performs phagocytosis of discs and removing waste products shed by rods and cones from the photoreceptors

Blood retina barrier

Reisomerizarion of all trans retinal into 11 cis retinal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the two types of photoreceptors and the type of vision they are responsible of

A

Rods (for night vision)

Cones (for day and color vision)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does the outer and inner segment of photorecptors contain

A

Outer segment contains opsins (photopigments) in a series of disc membranes

Inner segment is made up of a cytoplasmic region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the photopigments in rods and cones

A

In rods, is rhodopsin

In cones, is iodopsins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How many rods and cones are at the central of fovea (forveola)

A

No rods but highest concentration of cones (highest at foveola at macula area)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which part of the retina has a decreased number of receptors

A

ora serrata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the total rods bs total cones

A

Rodes:120 mil

Cones: 6mil

Cones is half of rods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the difference of the degeneration of discs in cones vs rods

A

In rods, disc always degenerating with new ones formed at the base of the outer segment

In cones, disc continually degenerate but new ones occur along the entire extent of the outer segment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Does cone or rods take longer to be renenewed

A

cones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How is the outer segment tip shed

A

shed from rods and cones thourhg phagocytosis by RPE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Which photopigment (in which type of photoreceptor) can be bleached

A

Rhodopsin in rodss (visual purple pigment) can be bleached, bu it also reversible

Bleached from purple to orange to yellow then to white

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the visual cycle

A

biological conversion of a photon into a electrical signal inthe retina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

State how the visual cycle takes place

A

Retinol (Vitamin A) is transported to the retina via the circulation, where it moves into RPE cells
- for storage, retinol is esterfied to form a retinyl ester

When required, retinyl esters are hydrolyzed and isomerized to form 11 cis retinol which is oxidezed to form 11-cis- retinal

11-cis-retinal can be shuttled to the rod cells where it binds to opsin to form rhodopsin

Absorption of a photon of light catalyzes the isomerization of 11-cis-retinal to all-trans-retinal and results in its release
- triggers phototransduction which leads to generation of electrical signal to the opic nerve and brain resulting in vision

Once released, all trans-retinal is reduced to all trans retinol, which can be transported back to the RPE to complete the visual cycle (“recharged”)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the process of the dark current in the retina

A

Inner segment of receptor, Na+ is pumped out and K+ is pumped in by Na+/K+ pump

K+ moved out of the inner segment due to concentration gradient

In the dark, Na+ flow from more conc. external solution into the outer segment through a channel (opens only in dark) and flow in to the inner segment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Explain photoreceptors
stimulation in dark

A

Na+ channel open

receptor cells depolarizesat the synaptic end

increase in posistiviy of membrane potential

Rate of release of neurotransmitter (glutamate) increases at synaptic end

Induces signal at bipolar and horizontal cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Explain photoreceptros stimulation in the light

A

Na+ channel closes

receptor cells hyperpolarizes at the synaptic end

Increase in negativity of membrane potential

Rate of release of neurotransmitter (glutamate) decreases at the synaptic end

Induces signal at the bipolar and horizontal cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is phototransduction

A

Process where absorption of light result in the closure of cation channels in the outer segment

Hyperpolarization (increase negativity)

Depolarization (increase positivity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the hypotheses

A

cyclic guanosine monophosphate (cGMP) keeps the cation channel open

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

State the process of phototransduction in the dark

A

In the dark, rods have high conc. of cGMP which keeps the cation channel open to allow entry of Na+

receptor depolarizes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

State the process of phototransduction in the light

A

In lightm stimulated rhodopsin activates hundreds of transducin molecules

Each transducin molecule activates 70 phosphodiesterase which hydrolizes more than 10k cGMP molecules

cGMP drops drastically as they are hydrolysed by phosphodisterass

Cation channels closed as cGMP is not present to keep it open

No Na+ can enter resulting in a change in inward current, receptor hyperpolarizes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the external limiting membrane made of

A

Made up of junctions between neuroglia (muller cell) and neural cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Why is the external limiting membrane not a continous structure/ is widely fenestrated

A

Widely fenestrated to allow the processes of the rods and cones to pass thr

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What does the outer nuclear layer consit of

A

rods and cones nuclei

Cones have little outer fibres so their nuclei lie closer to the external liminting membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What does the outer plexiform layer consit of

A

contains processes and synapses between rods and cones, horizontal and bipolar cells

31
Q

What are the type of bipolar cells in rods and cones

A

In rods, only rods bipolar cells

In cones, cone bipolar can be flat or midget types

32
Q

What are the stuctures that could be found in the inner nuclear layer

A

nuclei of the horizontal, bipolar, amacrine and muller cells

as well as cappilaries of the central retian vessels

33
Q

What are the strucures that can be found in the inner plexiform layer

A

processes and synapses of the bipolar, amacrine and ganglion cells

34
Q

How does the thickness of the inner plexiform layer vary across the retina

A

Uniform thickness everywhere in the retina except its absence at the fovea

35
Q

What is the difference of inner vs outer plexiform layer

A

Synapse are more complex in the inner plexiform layer vs the outer

36
Q

What are the structures located in the ganglion cell layer

A

Ganglion cells nucleim muller cell fibres and retinal vessels

(muller n vessels are found in the cells with nuclei)

37
Q

how does the thickness of the ganglion cell layer vary in the retina

A

Thick at the macula but absent at the fovea

38
Q

What are the three type of ganglion cells

A

Midget, diffuse, stratified

39
Q

What structure does the nerve fibre layer consist of

A

axons of the ganglion cells

(axons are in bundle)

40
Q

What is the division line at the temporal side of the macula what does it separate

A

It is the temporal retinal raphe and seprarates the arcuate fibres from the superior and inferior retina

41
Q

What is the bundle that consist of axons in the macula, state where it passes and heads to

A

papillo macular bundle
- consits of axons passing to the optic nerve head from the central retinal area

42
Q

What is does the inner limiting membrane do

A

form a junctin between the retina and the vitreous humour

(vitreous fibres and neuroglia cell processes contribute to this layer)

43
Q

What are the differnet types of cells present in the retina and where are they located

A

Photoreceptors (rods and cones)
- photoreceptors to outer plexiform layer

Bipolar cells
- outer plexiform to inner plexiform layer

Horizontal cells
- outer plexifrom to inner nuclear layer

Amacrine
- inner nuclear to inner plexiform layer

Nerve cell (muller cells)
- outer nuclear layer to inner nuclear layer

Ganglion cells
- ganglions cell to nerve fibre layer

44
Q

What do bipolar cells do

A

communicate throuhg the retina between the photoreceptors and ganglion cell

45
Q

What cells do the bipolar cell synapse with

A

Horizontal cell
Amacrine cell
Ganglion cell

(will not synapse with its own cell)

46
Q

What are the two tyep of bipolar cells and what this mean

A

Depolarizing

Hyperpolarising

In the dark or light condition, bipolar cells will be stimulated by photorecepors
- to release the excitatory transmitter at their endings to excite the amacrine and ganglion cells

47
Q

What is the function of the horizontal cells

A

communicate acros the retina rods and cones

48
Q

Where are horizontal cells found and what do cell do they excite

A

Found where the photorecptors synapse with the bipolar cells and excite the dendrites of the bipolar cell

49
Q

Which cells does the amacrine cell synapse and communciate with

A

Synapses with bipolar and communicates with ganglion cells and other amacrine cells

50
Q

What is the function of the amacrine cell

A

transmit and modifies signals across the retina within the ganglion cell layer

51
Q

Where are the nerve cells found

A

Fills up space not taken up by the cells and forms the external and inner limiting membrane

(main neuroglia cell in the outer half of the neural retina)

52
Q

what is the function of the nerve cells

A

surround cells to hold them in place

supply nutrients and oxygen to the cells

53
Q

What cells does the ganglion cell synapse with

A

bipolar and amacrine cells

54
Q

How does the thickness of the ganglion cells vary across the retina

A

Very thin at ora serrata and thickest at the macula

absent at the fovea

55
Q

What does the ganglion cell respond best and poorly to

A

Responds best to a small spot of lift in the center of its circular receptive field

Responds poorly to diffuse illumination

56
Q

What are the types of receptive field

A

“on” center and “off center

57
Q

What happens if light shines on the center of a on center cell

A

The ganglion cell fires rapidly

58
Q

What happens if light shines on the center of a off center cell

A

The ganglion cell does not fire

59
Q

What happens if light shines on the whole cell

A

Weak response low frequency firing

60
Q

Where is the macula located

A

3-4mm temporal to optic disc

61
Q

What can the macula be divided into

A

Fovea
Parafovea
Perifovea

62
Q

Are vessels present at the macula

A

No but sometimes cillio retinal artery may be present

63
Q

What is the blood supply to the macula

A

RPE and choroid capillary bed to supply the macular area

64
Q

What is the raio of cones, bipolar and ganglion cells in the fovea

A

1:1

65
Q

What is the photorecptor present in the foveola

A

Cones

Provides the greatest resolution

66
Q

Where does the optic disc lie

A

Lies 3mm medially to the maculla

67
Q

What is the average diameter of the optic disc

A

1.5 mm

68
Q

What is the nerve fibres that is located at the optic disc

A

Ganglion nerve fibres

69
Q

Which part of the retina is known as the physiological blind spot

A

optic discs

70
Q

What is the optic cup and neuroretinal rim

A
  • central part of the optic disc has a slight depression
  • edge of disc is slighyl raised
71
Q

What passes thoruhg the depression in the optic disc

A

Where the central retinal artery and vein passes thorugh in the centre, pass over the rim and radiate to supply the retina

72
Q

What provides the blood supply to the optic disc

A

the scleral circle of Zinn-haller

73
Q

What is the blood supply of the retina

A

Outer retina: photoreceptors and RPE, receive supply from choriocapillaries

Inner retina: supplied by central retinal artery a branch from opthalmic artery

74
Q

What is the blood drainage of the retina

A

Veins are mostly in correspondence with the artery will eventually drain into the cavernous sinus at the back of the eye

Ocular anatomy (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions