Neuro: Vision Flashcards
What are the 2 halves of the retina called?
- Temporal retina - half closest to temporal bone of skull
- Nasal retina - half closest to the nose
When looking at the world you have a temporal field of view and a nasal field of view, define each type of visual field
- Temporal field of vision - field of vision towards temporal bone
- Nasal field of vision - field of vision towards the nose
What part of the retina focuses light coming from temporal field of view and what part of retina focuses light coming from nasal field of view?
- Temporal retina focuse light from nasal field of view
- Nasal retina focuses light from temporal field of view
What is the sclera of the eye?
Sclera is the white fibrous outer layer of the eye

What is the cornea and how is it transparant?
- Cornea is the transparant front part of the eye
- It’s transparant because of the way that the collagen and cells that make up the sclera arrange themselves within the cornea

Why is there a need for the eye to produce intraocular pressure?
Intraocular pressure needed to keep the sclera rigid as it is flexible to a certain degree
How is intraocular pressure created within the eye?
Generated by aqueous humour (fluid that fills the space between cornea and lens)
What part of the eye produces aqueous humour and what part of the eye drains excess aqueous humour away?
- Produced by the ciliary body
- Excess aqueous humour drains into angle of the eye

As you get older what happens to the vitreous humour that fills most of the eye as someone gts older?
- Proteins that make up vitreous humour clump together
- This causes vitreous humour to shrink down and pull away from retina

What parts of the eye make up its optics?
- Cornea
- Lens
- Iris (pupil)
How is the lens able to change shape?
- Lens suspeneded by suspensory ligaments from the ciliary body
- Ciliary body contains ring of muscle and so when that muscle contracts or relaxes it causes the lens to change shape
What is the function of the iris?
Controls the diameter and size of the pupil and thus the amount of light that reaches the retina
Why does the iris need to control the size of the pupil?
- Iris needs to control size of pupil to ensure that light doesn’t hit the edge of the lens
- If light does hit edge of lens it won’t be focused onto retina properly
What are the different parts of the retina?
- Neural retina
- Retinal pigment epithelium

What are the functions of the retinal pigment epithelium?
- Provides biochemical support to photoreceptors
- Prevents retina from peeling away
What does the fact that both the retina and the retinal pigment epithelium developed from the neural tube mean for these structures?
Means they are both Central nervous sytem structures
Describe the pathway of the optic nerve from the retina to the primary visual cortex (Primary visual pathway)
- Axons of retinal ganglion cells within the neural retina run along surface of retina and converge to form optic nerve
- Optic nerve runs from retina down to the optic chiasm
- They continue from optic chiasm down optic tract to lateral geniculate nucleus (LGN)
- Cells of lateral geniculate nucleus project axons through optic radiation to the primary visual cortex

What happens to the axons of the retinal ganglion cells once they reach optic chiasm?
- Axons of retinal ganglion that are formed from the nasal retina cross over at optic chiasm
- Axons of retinal ganglion within nasal retina of the right eye cross over into the left side of the brain
- Axons of retinal ganglion that are formed from temporal retina DO NOT cross over at optic chiasm
What type of vision are the rod and cone photoreceptors responsible for?
- Rod photoreceptor - Night vision
- Cone photoreceptor - Day vision
What are the 2 main segments of the cone photoreceptor? What strictures does each segment contain?
- Outer segment - Phospholipid membrane discs
- Inner segment - Nucleus, axon and synaptic terminal

Why is the phospholipid membrane arranged into discs within the outer segement of the cone photoreceptor?
It arranges the chromophore between the membrane discs into layers perpendicular to light path
Describe what is happening within a cone photoreceptor when it’s a resting potential
- Resting potential of cone photoreceptor around -45mV (slightly depolarised)
- At resting potential K+ moves out of inner segement via K+ channels
- Within outer segment there are Na+ channels open that allow influx of Na+ into outer segement
- This causes slight depolarisation which allows for release of Glutamate from synaptic terminal
Describe what happens when light starts to hit cone photoreceptor
- Light hitting outer segement causes some of the Na+ channels on outer segement to close leading to less Na+ influx and less depolarisation
- K+ channels of inner segement still open so cone photoreceptor becomes hyperpolarised due to K+ efflux
- Hyperpolarisation prevents glutamate release from synaptic terminal
Within the outer segment what molecule is responsible for keeping the Na+ channels open?
cGMP










