Brainscape's Knowledge GenomeTM

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


See full index

NSB Lectures > Physiology of Vision > Flashcards

Physiology of Vision Flashcards

1
Q

What are the three layers of the eyeball?

A

Outer fibrous layer (sclera)
Middle vascular layer (choroid)
Inner neural layer (retina)

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

In which layer does the biochemical activity and hyperpolarisation take place?

A

Inner neural layer

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

What happens at bright light enters the eye?

A

Pupil constricts

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

What happens when the light is dim?

A

Pupil dilates

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

What allows the pupil to change size?

A

Muscles of the iris

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

What produces a focused image on the retina?

A

Cornea & lens

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

How is focus changed in the eye?

A

By varying the shape of the lens

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

What do cataracts do?

A

Make the lens opaque - stops light entering the eye making it difficult to see

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

What changes the power of the image in the eye?

A

Iris (constricting and dilating) can vary diameter x4 - which varies retinal intensity by x16.

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

What absorbs unwanted light in the eye?

A

A pigmented layer being the retina

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

How many times does light bend in the eye?

A

Twice - once when passing through the cornea and once when passing through the lens.

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

Which part of the eye bends the light the most?

A

Cornea - bends 2/3rds

Lens - bends 1/3

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

What shape is the lens?

A

Biconvex

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

Does a convex lens converge or diverge light rays?

A

Converging - brings rays together

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

Does a concave lens converge or diverge light rays?

A

Diverges light rays - spreads them apart

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

What is the refractive power of a lens measured in?

A

Diopters

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

What is the focal length of a lens?

A

Distance between a convex lens and its focal point (where the rays converge)

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

What can affect the focal length of a lens?

A

Genetics
Pathology

Length of eyeball
Curvature of lens

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

What is long sightedness called? What is it caused by?

Where is the focal point of the lens?

A

Hypermetropia (Hypermetropic)

Eyeball too short or Lens too weak

Focal point - behind the retina

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

What is short sightedness called? What is caused by?

Where is the focal point of the lens?

A

Myopia

Eyeball is too long to lens is too strong.

Focal point - in front of the retina

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

What is the most common refractive disorder of the eyeball? What is it caused by? What does it do to vision?

A

Astigmatism

Caused by curved eyeball (more rugby than football)

Means that light is focussed in more than one place.

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

Which refractive disorder is more common in the elderly? What does it do?

A

Presbyopia

Caused by laxity of the lens - doesn’t return to its normal shape

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

What type of lens do you need as a corrective lens for myopic patients?

A

Concave (diverging)

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

What type of lens do you need as a corrective lens for hypermetropic patients?

A

Convex (converging)

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

Where does the optic nerve leave the eye?

A

In the optic disc

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

Which is most sensitive part of the retina? How does it appear under an ophthalmoscope?

A

Fovea

Small yellow spot - far eyeball

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

What does the fovea have?

A

Lots of special cones for detailed vision

29
Q
A
30
Q

Which cells are found in the neural layer?

A

Ganglion cells
Bipolar cells
Photoreceptor cells (rods & cones)
Amacrine & horizontal cells (supportive)

31
Q

What do rods detect?

A

Black & white vision
Night vision
Dim light

32
Q

What do cones detect?

A

Colour vision & bright light

33
Q

What happens once photoreceptors are excited?

A

Signals are transmitted through the retina (photoreceptors to bipolar cells to ganglion cells) to the optic nerve fibres and then to the occipital cerebral cortex

34
Q

What is the process by which photons of light are converted to electrical signals?

A

Phototransduction

35
Q

What is the visual pathway in the brain?

A

From optic nerve to optic chaism to optic radiations and to the occipital cortex.

36
Q

Do we have more rods or cones?

A

More rods (120m to 5m)

37
Q

How many layers is the retina made of?

A

3 direct (receptors, bipolar cells and ganglion cells) and 2 transverse layers (horizontal and amacrine cells)

38
Q

What are the function of the transverse layers of the retina?

A

Signal processing including lateral inhibition

39
Q

What are the photosensitive pigments found in rods and cones?

A

Rods = Rhodopsin

Cones = Photopsin - each one has either red-sensitive, green-sensitive or blue-sensitive pigment

40
Q

What type of channels are used in phototranduction?

A

cyclic Guanosine Monophosphate (cGMP)

41
Q

What is the difference between different colours?

A

Their wavelength (Red 570, Green 535 and Blue 445)

42
Q

What causes colour blindness?

A

Loss or modification of one of the three cone pigments.

43
Q

Which gene carries the red and green pigments? What does this explain?

A

X

Why colour blindness is more common in males than females

44
Q

Which gene carries the blue pigment? Why is this rarer?

A

Found on chromosome 7 (not sex-linked) = which means it is much rarer to find as usually are 2 copies of chromosome 7.

45
Q

What does the visual system in the brain comprise of?

A

Eye
Optic nerve
Optic chiasm
Optic tract
Lateral geniculate nucleus
Optic radiation
Visual Cortex
Visual Association Cortex

46
Q

Which nucleus is found after the optic chiasm?

A

Lateral geniculate nucleus

47
Q
A
48
Q

What are the two fields of vision?

A

Temporal
Nasal

49
Q

What does the optic nerve from each retina do after leaving the eye?

A

Divides into L & R halves

50
Q

What happens to the two halves of the optic nerves in the chiasm?

A

L halves and R halves from each eye combine to form optic tracts

51
Q

Where do optic tracts relay? Where in the brain is this found?

A

Lateral geniculate nucleus
Found in the thalamus

52
Q

Where does part of each optic tract travel to?

A

Superior colliculus in the mid-brain

53
Q

Where does the output from the lateral geniculate nucleus go?

A

To the striate cortex in the occipital lobe.

54
Q

Which Brodmann area is the primary visual cortex?

A

17

55
Q

What do the following lesions cause?

A
55
Q

What do the following lesions cause?

A
56
Q

What is the term of loss of vision in the same half of both eyes?

A

Homonymous hemianopia

57
Q

What is the term for loss of vision in opposite halves of both eyes?

A

Bitemporal hemianopia

58
Q

What is the term of loss of vision centrally?

A

Scotoma

59
Q

What can cause scotomas?

A

Retinal damage
Lesions in visual cortex
Tumours in optic nerve, chiasm, tract or radiation.

60
Q

What is a common cause of bitemporal hemianopia?

A

Pituitary adenomas

61
Q

Which stream of the cortex is concerned with locomotion, motion & action?

A

The dorsal stream

62
Q

Where is the dorsal stream found in the cortex?

A

From the occipital to parietal cortex

63
Q

Which stream of the cortex is concerned with object & face identity and conscious perception?

A

Ventral stream

64
Q

Where is the ventral stream found in the cortex?

A

From the occipital to the temporal cortex

65
Q

Which disorder means that a patient is unable to recognise and identify visually presented objects or persons despite having normally functioning senses?

A

Visual agnosia

66
Q

What causes visual agnosia?

A

Problems between the occipital lobe and the temporal lobe - is a ventral stream problem.

67
Q

What is the inability to recognise familiar faces called?

A

Prosopagnosia

NSB Lectures (48 decks)

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