Brainscape's Knowledge GenomeTM

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


See full index

mnsr > mnsr 31 > Flashcards

mnsr 31 Flashcards

1
Q

eyes have developed —- at least — times in —-

A

independently, 3, metoza as arthropods, mollelus, and vertebrates

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

image formation requires a

A

lens - the eye

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

the independent development of the eye is an example of

A

convergent evolution

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

the eye converts

A

light energy into electrical signals using photoreceptors cells
- eye placement , binocular vision
- wider field of view
- distance and depth perception

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

for horizontal movements we use

A

medial and lateral rectus muscles

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

for vertical movements we use

A

posterior and anterior rectus muscles and superior and inferior oblique

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

eye movement can be — when we —- or can be —- by maintaining focus while moving our head aka vestibular ocular reflex

A

conscious, focus, unconscious

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

the tunic layers of the eyes

A

1- fibrous layer: scalera and cornea
2- vascular layer:iris, choriod, ciliary body
3- retina layer: pigmentent layer, natural layer

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

the outermost layer of the eyes composed of dense connective avascular tissue

A

fibrous layer

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

the function and properties of the scalera

A
  • white, opaque layer
  • provides strength and protection
  • has an attachment point for extra ocular muscles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

the function of the cornea

A
  • transparent layer
  • 2/3 of the focusing power allowing the light to enter the inner eye
  • the corner can be reshaped by laser or transplanted from donor patient,
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

the vascular/ uvea layer consist of

A
  • lens
  • iris
  • choroid
  • cillary body and ligaments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

the function of the choroid

A
  • supplies nutrients and 02 to the retina
  • layer of blood vessels
  • contains melanin , reduces reflection of light
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

the function of the ciliary body

A
  • ring shaped structure
  • consist of: radial ciliary muscles and cirucllary mucles
  • suspensory ligaments and zonule filaments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

the lens has

A
  • transparent and consist of:
  • inner epithelial layer
    -lens fiber cells
  • lens corspule - basement membrane
  • it separates the aqueous humour from the front and the vitreous humour behind
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

the function of the iris

A
  • circular ring structure
  • has radial pupillary dilators muscles
  • circular pupillary sphincters
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

in bright light, the pupil constricts by

A

cirucallry muscle contract in the parasynpthatic

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

in dim light, the pupil dilates by

A

radial muscles constricts in sympathetic

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

nervous/sensory tunic layer - retina layer consist of

A
  • inner epithelial pigmented layer w/ melanin
  • natural layer w/ inner light sensitive consist of photoreceptors( modified nerve cells to detect light), bipolar cells and retinal ganglion cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

—- consist of large concentration of the cones and the largest density at —-

A

macula , fovea
for high resolution, color and central vision

21
Q

damage in the macula is

A

macular degeneration

22
Q

optic disk consist of

A

optic nerve and blood vessels

23
Q

— is an area w no photoreceptors

A

blindspot

24
Q

rods and cones are in contact w —— that provides —-

A

pigmented epithelium, retinal for rhodopsin

25
Q

both rods and cones contain numerous —- of the plasma membrane and they contain —-

A

discs/ foldings, contains photopigment and the discs increase the light absorbing surface area

26
Q

— is back to front in relation to light entering the eye

A

retina
- the photorecptors face away from the incoming light

27
Q

the retina has five main types of neurons

A
  • ganglion
  • amacrine
  • horizontal
  • bipolar
  • photoreceptors ( rods and cons )
28
Q

rods, cones, bipolar and ganglion release —-
horizontal and amacrine release —-

A

glutamate ( excitatory )
GABA ( inhibitory )

29
Q

the fucntions of amacrine and horizontal cells

A

both are lateral interneurons and both help in the process of visual input in the retina
- HCs: connection between photoreceptors and bipolar cells
- ACs: connection between bipolar and ganglion cells

30
Q

ganglion cells receive impulse for

A
  • brightness, motion, color
  • they are sensitive to light
  • don’t play a role in vision BUT it can control the pupil size and synchornizng the circadian rhythms
31
Q

are repsonsible for the photooptic vision

A

cones cells

32
Q

activated in bright light, good visual details, is color sensitive

A

cones cells

33
Q

nocturnal animals contain mainly

A

rods

34
Q

responsible for high sensitivity but poor discrimination - scotopic vision

A

rods

35
Q

rods work best in — illuminatuin and is not functional in bright light bc - photo-sensitive pigment is degraded by bright light.

A

low illumination

36
Q

rods need time to adapt aka the dark adaptation which takes

A

30-60 minutes

37
Q

The visual pigment of the rods is rhodopsin
Consists of:

A

Opsin protein
Cofactor 11-cis-retinal

38
Q

11-cis-retinal is derived from

A

11-trans-retinol and vitamin A

39
Q

11-cis-retinal is maximally sensitive to

A

blue-green in the 500nm wavelengths and does NOT react to red light

40
Q

Cis-retinal rests within a pocket in the

A

opsin protein

41
Q

A deficiency of vitamin A leads to —– and eventual deterioration of the outer segments of the rods

A

night blindness

42
Q

explain the visual cycle

A

Light isomerises the 11-cis-retinal to 11-trans-retinal
Induces conformational change in the protein structure to generate activated rhodopsin.
Activated rhodopsin activates other signalling proteins, resulting in generation of a signal.
Activated rhodopsin quickly breaks down into the protein opsin (scotopsin in rods), releasing 11-trans-retinal
Later the 11-trans-retinal is reconverted to 11-cis-retinal by an enzyme
Rhodopsin very sensitive - a single photon of light energy can excite a single rod cell
Approx. 5 rods need to be excited before a flash of light is seen
There are about 125 million rods in each retina mostly away from the fovea.
Dark adapted, indirect gaze in low light can discern objects in shades of grey or silver. Light level below the threshold of colour sensitivity

43
Q

the summation effect is the

A

In the fovea the ratio of cones to ganglion cells is almost 1 : 1
High visual acuity
Peripheral areas of the retina may have some 300 rods / optic fibre
This explains the greater sensitivity in these areas to weak light because of the summation effect

44
Q

no. of cones and rods

A

6 million, 120 million
- we have 900,000 optic nerve axons
- 140 rods per 1 ganglion cells
- 6 cones per 1 ganglion cell

45
Q

The three types of cones

A

-Blue sensitive (max 430nm),
-Green sensitive (max 530nm)
-Red sensitive (max 562nm)
-Each contains a slightly different opsin - maximally sensitive to different wavelengths of light.

46
Q

Visible spectrum in humans is between

A

380nm and 760 nm

47
Q

most primates are — most mammals expect primates are — vertebrates as birds/reptiles/fish/amphilia have —

A
  • trichromatic
  • dichromatic
  • 4 classes of cones
48
Q

color blindess genes encoding the —- and is linked to —-

A

green and red sensitive (commonest type ), X chromosomes
- 1:12 males
-1:200 females

49
Q

the opening of the iris ( the coloured part of the eye) is called

A

the pupil

mnsr (22 decks)

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