Brainscape's Knowledge GenomeTM

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


See full index

PHTH 7303 Neuro > Exam 3 Week 14 ppt 1&2 Retinal structure and function > Flashcards

Exam 3 Week 14 ppt 1&2 Retinal structure and function Flashcards

1
Q

purpose of photoreceptors of the retina

A

convert photonic energy within the electromagnetic spectrum with wavelengths between 400 to 700 nm to electrical signals

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

What is generated from the signals of the retina sent to the brain?

A

a complex 3 dimensional world from a 2 dimensional input on the retina

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

One of three critical systems for balance

A

vision

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

Retina has how many major classes of cells?

A

7

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

Retina has how many histologically distinct layers

A

10

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

Two structures that make up the deepest cellular layer of retina

A

Rods and cones

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

Rods are photopic or scotopic?

A

scotopic

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

What does scotopic mean?

A

sensitive to low light levels but insensitive to color

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

Cones are photopic or scotopic?

A

photopic

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

What does photopic mean?

A

works at higher light levels but come in 3 forms with each sensitive to different color spectrum

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

How many rods and cones does each eye have?

A

80-110 million rods and 4-5 million cones

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

How are photoreceptors of rods and cones similar? (4)

A
  1. photosensitive outer segment with the photosensitive pigments
  2. Inner cytoplasmic segement (rich in mitochondria)
  3. Nuclear region
  4. Specialized presynaptic endings with invaginations which interfold with bipolar and horizontal cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How are photoreceptors in rods different? (3)

A
  1. Not in the fovea/macula lutea
  2. Highest concentrations just lateral to fovea
  3. High concentrations maintained in periphery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How are photoreceptors in cones different? (2)

A
  1. Most concentrated in the fovea/macula lutea

2. Very low density elsewhere

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

Which area has the highest density of photoreceptors?

A

fovea/macula lutea

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

Significance of highest density of photoreceptors in the fovea/macula lutea

A

this is the area with the highest visual acuity

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

Significance of the lack of rods in the fovea and high densities in the retinal periphery

A

the periphery of the field of vision has a higher low light sensitivity

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

Cell types in fovea

A

direct cone to bipolar to ganglion cell

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

Cells in peripheral retina

A

additional cells to allow interaction between photoreceptor and ganglion cells

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

Bipolar cells- 3 points to note

A
  1. Analogous to primary afferents, receive input from photoreceptors
  2. Specific to types of photoreceptors
  3. in ON and OFF varieties
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Horizontal cells- 3 points to note

A
  1. Laterally interconnecting interneurons which integrate and regulate the input from multiple photoreceptor cells
  2. Produce an integrated “lateral inhibition” on photoreceptor cells
  3. Enhance contrast
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Amacrine cells- 3 points to note

A
  1. Laterally interconnecting interneurons which integrate and regulate the input from multiple bipolar cells
  2. Produce an integrated “lateral inhibition” on both bipolar and ganglion cells
  3. Enhance contrast
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Ganglion cells- 3 points to note

A
  1. Analogous to 2° neurons of relay nuclei of other sensory systems
  2. Most superficial layer of neurons whose axons exit retina as the optic nerve
  3. > 100 million retinal receptor cells but only 1 million ganglion cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Where is the greatest and least amount of convergence of photoreceptor cells onto Ganglion cells

A 
greatest= peripheral rods 
least= foveal cones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

two types of ganglion cells

A

M (magnocellular) type and P (parvocellular) type

26
Q

P (parvocellular) type cells- 3 points to note

A
  1. Small receptive fields
  2. Specific to detail
  3. Sensitive to color and visual acuity (form)
    (these are one of two types of ganglion cells)
27
Q

M (magnocellular) type cells- 4 points to note

A
  1. Large receptive fields
  2. Not sensitive to color
  3. Very sensitive to low illumination
  4. Sensitive to gross patterns (location) and movement
    (these are one of two types of ganglion cells)
28
Q

How do Photoreceptors work?

A
  • Membranes depolarized so release glutamate in dark

- Light reacting with membrane bound opsins hyperpolarizes the membrane so decreases glutamate release

29
Q

How do bipolar cells work?

A
  • Glutamate both depolarizes and hyperpolarizes bipolar cells depending upon type of glutamate receptor
  • Produces OFF and ON bipolar cells
  • OFF cells inactive in light (OFF is active in the dark)
  • ON cells active in light (ON is active in the light)
30
Q

Which cells respond in an annular way to light on the retina?

A

Bipolar and Ganglion cells

31
Q

What happens to inner and peripheral region when cells respond in an annular way to light?

A

Inner “central” region responds one way and peripheral “surround” responds another.

32
Q

What causes inner and peripheral regions to respond differently?

A

Due to action of horizontal and amacrine cells

33
Q

Which cells have an “On” center - “Off” surround

A

Bipolar and Ganglion cells

34
Q

“On” center and “Off” surround

When light hits on the center of annulus on surface of retina then the bipolar or ganglion __________________

A

cell fires, but is then quiet when light off

35
Q

“On” center and “Off” surround

When Light on surround of annulus then bipolar or ganglion________

A

cell is inactive until light turned off on that outer region, when the cell then becomes active

36
Q

“On” center and “Off” surround

When Light shines on both center and surround then_____

A

there is some activity in the cell but less activity than when light is only on the center

37
Q

“Off” center and “On” surround

When Light shown on center of annulus on surface of retina then__________

A

ganglion cell is quiet then active when light goes off

38
Q

“Off” center and “On” surround

When Light on surround of annulus then_________

A

cell active until light turned off then quiet

39
Q

“Off” center and “On” surround

When Light shines on both center and surround then______

A

there is some but less activity than when light is only on the outer annulus

40
Q

“On” center - “Off” surround

When light hits on the center of annulus on surface of retina then the bipolar or ganglion __________________

A

cell fires, but is then quiet when light off

41
Q

“On” center - “Off” surround

When Light on surround of annulus then bipolar or ganglion________

A

cell is inactive until light turned off on that outer region, when the cell then becomes active

42
Q

“On” center - “Off” surround

When Light shines on both center and surround then_____

A

there is some activity in the cell but less activity than when light is only on the center

43
Q

“Off” center - “On” surround

When Light shown on center of annulus on surface of retina then__________

A

ganglion cell is quiet then active when light goes off

44
Q

“Off” center - “On” surround

When Light on surround of annulus then_________

A

cell active until light turned off then quiet

45
Q

“Off” center - “On” surround

When Light shines on both center and surround then______

A

there is some but less activity than when light is only on the outer annulus

46
Q

In what way do Bipolar and Ganglion cells provide enhanced contrast?

A
  • With sharp delineations between active and not active at borders of light and dark
  • This particularly true in peripheral vision
  • In macular degeneration see contrasts but not detail
47
Q

What is the blind spot?

A
  • Circular, elevated region where ganglion cell axons gather to leave the eye as the optic nerve
  • Devoid of rods and cones, represents the blind spot in the visual field
48
Q

Where does neural retina receive its blood supply? (2)

A
  1. Outer retinal layers via choroidal capillaries
  2. Inner retinal layers via central retinal artery, a
    • Branch of the opthalmic artery from the internal carotid
49
Q

What would result from blockage of central retinal artery?

A

Sudden blindness

50
Q

Age-related macular degeneration (AMD)- 4 points to know

A
  1. Increases in prevalence in sixth decade
  2. Leading cause of blindness in the elderly
  3. Loss of central vision and acuity
  4. Preserved peripheral vision and ability to determine contrasts
51
Q

Two types of Age-related macular degeneration (AMD)

A
  1. Dry

2. Wet

52
Q

Most common type of Age-related macular degeneration

A

Dry

53
Q

Which type of AMD is caused by detachment of retinal pigmented epithelium due to hypervascularization?

A

Wet

54
Q

Which type of AMD is caused due to atrophy of retinal pigmented epithelium (RPE)?

A

Dry

55
Q

Optic nerve- 4 points to know

A
  1. Arises from ganglion cells of the ipsilateral eye, is part of the CNS
  2. Myelinated by oligodendrocytes
  3. The optic nerve is ensheathed by pia, arachnoid and dura, and thus has subarachnoid space with CSF.
  4. Increased intracranial pressure causes bulging of the optic disc called papilledema
56
Q

from where do the outer retinal layers receive blood supply?

A

via choroidal capillaries

57
Q

from where do the inner retinal layers receive blood supply?

A

via the central retinal artery, which is a branch of the opthalmic artery, which is from the internal carotid artery

58
Q

Retinal blood supply: what artery does the opthalmic artery supply, and where does it come from?

A

the opthalmic artery supplies the central retinal artery (which supplies the inner retinal layers)
The opthalmic artery comes from the internal carotid artery

59
Q

retinal blood supply: what artery does the internal carotid artery supply?

A

the opthalmic artery (which supplies the central retinal artery which supplies the inner retinal layers)

60
Q

what is papilledema?

A

bulging of the optic disc because of increased intracranial pressure

61
Q

retinal blood supply: what do choroidal capillaries do?

A

it supplies the outer retinal layers

PHTH 7303 Neuro (89 decks)

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