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NEEUUUUUURRRRRRROOOOO > Vision > Flashcards

Vision Flashcards

1
Q

What does the outer fibrous layer of they eye have?

A

Has a non-sketchy sclera around the outside

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2
Q

What happens to the sclera at the front of the eye?

A

Becomes the non-transparent cornea the front of they eye

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3
Q

What is the cornea at the front of the eye inflated by?

A

Inflated by fluid

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4
Q

What humor is nicely hydrated and where is it located?

A

vitreous humor is nicely hydrated and is located at the back

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5
Q

What allows cornea to bend light rays?

A

Cornea is highly curved so bends light rays

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6
Q

What does the lens do?

A

Lens inside bends light further

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7
Q

What is the lens suspended on the ends of?

A

Suspended on the ends of suspensory ligaments from the cillary body

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8
Q

What does the cillary body include and what can this do?

A

Cillary body includes a muscle which can contract and relax making the lens fatter or flatter

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9
Q

What does a fatter lens do to light?

A

Fatter lens refracts light more

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10
Q

What does the iris control?

A

Iris controls central size of pupil and amount of light entering eye

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11
Q

What is the cornea primarily responsible for?

A

Primarily responsible for focusing light rays

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12
Q

What does a lens additionally provide?

A

lens provide additional variable fine focus

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13
Q

What is the job of the pupil?

A

Pupils job is to stay as small as possible to improve focus

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14
Q

Why is the retinal pigment epithelium an important structure?

A

Important structure as it keeps the neural retinal alive

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15
Q

What is the neural retina?

A

Neural retina is an outpost of the brain and generated from the neural tube

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16
Q

What does the neural retina contain and what does this link?

A

Neural retina contains a neural circuit which links the photo receptors to the retinal ganglion cells

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17
Q

What is the primary visual pathway?

A
  • Axons from the retinal ganglion cells project back via the optic nerve
  • The 2 optic nerves meet at the optic chiasm
  • The optic nerves run along the optic tract which dives up the brain
  • Many of the axons have branches that extend to the brain stem
  • Main branch goes to the lateral geniculate nucleus in the thalamus
  • Relay cells are activated in the LGN that carry signals to the primary visual cortex
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18
Q

What are rod receptors for?

A

For night vision

19
Q

What are cone receptors for?

A

For day vision

20
Q

What is the structure of cone photoreceptors?

A
  • Outer segment involves membrane discs

- Inner segment involves nucleus

21
Q

What is the membrane potential of cone photoreceptors?

A

-45mV

22
Q

Why are cone photoreceptors polarised?

A
  • They’re polarised because they have K+ channels that are leaking out
  • Also have channels in there outer-segments that leak Na+ in and these are open by default
23
Q

What happens if light over outersegment gets brighter?

A

If light over outer-segment gets brighter, the cell hyperpolarises reducing release of glutamate

24
Q

What happens if light over outersegment gets darker?

A

If light over outersefment goes darker, the cells depolarise and more Na+ channels open and more release of glutamate

25
Q

Where is opsin present?

A

Opsin present on membrane discs in outer segment

26
Q

What is the protein component of photopigment?

A

Opsin

27
Q

What is the non protein component of photo pigment?

A

Retinal

28
Q

What are the 2 components that photopigment is made up of?

A
  • Opsin

- retinal

29
Q

Steps involved in the initiation of light response in transduction

A

11-cis C bind is fairly unstable in retinal

  • When light strikes the retinal, it ruptures that bond and when the bond reforms it forms in the trans configuration
  • All trans retinal acts an agonist on a GPCR
  • Leads to the activation of G proteins which activate enzymes that breakdown cGMP
  • This allows Na+ to close
30
Q

Steps involved in the termination of response in transduction

A
  • The opsin gets capped off by enzymes which causes trans retinal to go away
  • Opsin stops activating protein and stops activating enzymes
  • Enzymes form cGMP
  • 11 cis retinal then binds to opsin again
31
Q

What does loss of peripheral vision occur due to?

A

Occurs due to glaucoma, retinitis pigmentosa

32
Q

What happens if you lose your fovia?

A

You are registered blind

33
Q

What do photoreceptors communicate via to the ganglion cells?

A

Photoreceptors communicate via bipolar cells to the ganglion cells

34
Q

How do bipolar cells gather information and why is this done so?

A

Bipolar cells gather information through a whole pool of photoreceptors before passing it on to the ganglion cells so there is convergence in the pathway

35
Q

What does convergence increase and what does this mean?

A

Convergence increases pixel size therefore that’s why peripheral vision is more blind

36
Q

Why don’t blood vessels cross the fovea?

A

Blood vessels don’t cross fovea because that’s where the foveal pit is

37
Q

What types of images do you get at the foveal pit and why?

A

You get high detailed images at the pit because you can get good focus on the image

38
Q

What cones are in the foveal pit?

A

Only red and green cones in this area

39
Q

What is the image inverted by and so what does this mean?

A

Image in inverted by the optics

-So left side of the image found on the right side of both retinae

40
Q

What do axons from nasal retina do?

A

Axons from nasal retina swap sides therefore right side of both retinae go to the right side of the brain

41
Q

What is the image mapped on to?

A

Image is mapped on to the LGN and cortex with expanded central regions of the image

42
Q

What do the axons form in the LGN and cortex?

A

Axons form a retinotopic map in the LGN and cortex with the map for the 2 eyes in register

43
Q

What does the retinal ganglion cells report?

A

Report changes in illumination form one location to another

44
Q

What happens if theirs a change in brightness causing the excitation of a ganglion cell?

A

If there’s a change in brightness causing the excitation of a ganglion cell, then information from excited cones will be fed through an inhibitory interneuron and they’ll inhibit that ganglion cell
-This means its not responding to absolute illumination, its the difference between brightness of the center vs the surroundings

NEEUUUUUURRRRRRROOOOO (20 decks)

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