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Physiology > 25-26 - Vision > Flashcards

25-26 - Vision Flashcards

1
Q

The main refractive part of the eye is the…

A

Cornea (not the lens!)

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2
Q

The pupil allows…

A

Entry of light into the eye

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3
Q

The iris contains…

A

Circular and radial muscles controlled by the ANS (determind by light level and emotional signals)

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4
Q

The lens allows for accomodation, the…

A

adjusting of focus over varying distances

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5
Q

The retina is the layer at the back of the eye, which is in fact part of the brain. It contains (5)…

A

the photoreceptors, horizontal cells, bipolar cells, amacrine cells, ganglion cells and nerve fibres.

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6
Q

Field of vision of each eye is…

A

150°

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7
Q

Accomodation involves the cillary muscles. When relaxed, they pull the ligaments taught, which…

A

Flattens the lens (for longer range vision)

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8
Q

When the ciliary muscles contract, the ligaments slacken, which…

A

Rounds the lens (for closer range vision)

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9
Q

The fovea is located at the…

A

Centre of the macula

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10
Q

The area of highest visual acuity is the…

A

Fovea (highest density of cones)

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11
Q

Cones are responsible for…

A

Colour vision in high light (Photopic)

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12
Q

Rods are responsible for…

A

Black and white vision in low light (Scotopic)

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13
Q

Ganglion cells and bipolar cells are located (in front of / behind) the rods and cones…

A

In front of

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14
Q

At the back of the retina is the…

A

Pigment epithelium in which photoreceptors are embeded

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15
Q

Why does the pigment epithelium contain melanin?

A

The black pigment prevents scattering by absorbing stray light = improved image quality

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16
Q

Cones come in 3 varieties…

A

Long reds, green mediums and blue shorts

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17
Q

Rods become…

A

Bleached in high light

18
Q

Bleaching of rods is why adaptation to dark…

A

Takes time

19
Q

Rods contain rhodopsin which is

A

Opsin + 11 Cis-retinal

20
Q

In the dark opsin and retinal are…

A

Bound

High cGMP, Na+ cannels are open, rod is depolarised and there is constant transmitter release 🌚

21
Q

In the light opsin and retinal are…

A

Split (bleaching)

Occurs due to hyperpolarisation of rod, decreasing NT release 🌞

22
Q

The visual system in the brain is divided into 2 streams (dorsal and ventral) these correspond to…

A

Where and What respectively

23
Q

Neurones in the visual cortex are more selective, responding to…

A

Bars and edges, specific positions and orientations, stimulus moving in a specific direction

24
Q

Which NT is released by photoreceptors…

A

Glutamate

25
Q

Horizontal and amacrine cells have the job of…

A

Spreading signals horizontally across the reitna

26
Q

Action potential come from the..

A

Ganglion cells

27
Q

Graded potentials come from the…

A

Photoreceptors, bipolar cells, horizontal and amacrine cells (everything before ganglion cells)

28
Q

The receptive field of a ganglion is the…

A

Small area of the retina at which light affects the ganglion cell

29
Q

Ganglion cells configured in a…

A

Centre surround organisation

30
Q

Centre surround organisation allows detection of…

A

Contrast (edges of discrete objects, e.g. change)

31
Q

Centre surround organisation is present for both…

A

Rod and cone ganglions cells

32
Q

2 types of cone ganglion centre surround configurations are…

A

Red-green and Blue-yellow

33
Q

White light has what effect on cone ganglion cells (of all configs)…

A

Weak firing and balanced excitation and inhibition

34
Q

Optic fibres cross over at the…

A

Optic chiasm

35
Q

Overlap between 2 fields of view allows…

A

Stereoscopic ‘3D’ vision

36
Q

Vision is processed in the L and R lateral geniculate nuclei. Notably the signals from…

A

each eye are processed on the opposite side.

L eye -> R GN
R eye -> L GN

37
Q

Which are more selective, lateral geniculate neurons, ganglion cells or cortical neurones in the visual cortex?

A

Cortical neurones

38
Q

The response of the visual cortex is generate by overlapping inputs from the …

A

Lateral geniculate nuclei (LGN)

39
Q

There are various areas of…

A

Visual processing in the cortex (colours, faces, etc)

40
Q

Dorsal stream…

A

WHERE 🐬 (dorsal fin, dolphin, where can I find dolphins)

41
Q

Ventral stream…

A

WHAT 😤 (venting about what)

Physiology (17 decks)

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