Vision. Structure of the Eye. Flashcards
What are the specialised senses of the body?
Vision.
Hearing.
Balance.
Taste.
Smell.
The organs that give rise to special senses are all located in what part of the body?
The head.
What kind of nerves carry information relating to the specialised senses?
Cranial nerves, not spinal nerves.
Do cranial nerves have 1st, 2nd and 3rd order neurons?
Yes.
What is the major difference between the nerves that carry specialised senses and normal nerves?
The nerves that carry specialised senses have a specialised receptor cell that picks up the stimulus.
What name is given to the ganglia in the brain?
Nuclei.
Where are sensory and motor nuclei located within the brain?
Sensory nuclei are located dorsally within the brainstem.
Motor nuclei are located ventrally within the brainstem.
What part of the brain will most cranial nerves originate from?
The nuclei of the brain stem.
Where do the 1st order neurons of special sensory organs run from and to?
From the sensory organs will travel into the brainstem.
For specialised sensory information, where does synapsis from 1st to 2nd order neurons occur?
In the brainstem.
Where do the 2nd order neurons of special sensory organs run from and to?
From the brainstem to the thalamic region.
For specialised sensory information, where does synapsis from 2nd to 3rd order neurons occur?
In the thalamus.
Where do the 3rd order neurons of special sensory organs run from and to?
From the thalamus to the area of the cortex that corresponds to the location where the stimulus was generated.
E.g. The visual cortex.
What cranial nerves do not have a specialised area of the cortex?
Cranial nerves 1 and 2.
What is vision?
The ability to see light.
What is light?
An electromagnetic wave.
How does light get into our eyes?
The elctromagnetic wave is emitted by a source travels until it bounces off an object.
It is only when it has bounced off that object that we are able to see it.
What happens to light as it enters the eye?
It is refracted and forced through the pupil.
Why is light refracted by the pupil of the eye?
It concentrates the incoming light and allows it to fall onto the retina.
Where in the eyeball is the retina located?
At the back of the eye.
What is the job of the retina?
To transduce the electromagnetic energy into electrical impulses which can be sent to the brain.
What determines the amount of light that enters the pupil?
The lens of the eye.
What part of eye allows us to focus on objects at different distances?
The lens.
What animals are able to change the curvature of their lens?
Birds.
Reptiles.
Mammals.
What animals are able to change the distance between the retina and the lens?
Most invertebrates.
What is the lens of the eye composed of?
4 refractive indices.
What area of the eye has a pigmented epithelium?
The retina.
What part of the eye contains the rods and cones?
The retina.
What part of the eye absorbs the incoming light?
The rods and cones of the retina.
What happens in the eye once the rods and cones have picked up the light?
They activate a ganglion cell (1st order neuron) which will then travels to the brain.
How do the first order neurons (ganglia) leave the eye?
They leave the eye separately and then join together to form the optic nerve.
A ganglion cell (first order neuron) receives inputs from how many photoreceptor cells?
From multiple photoreceptor cells.
What name is given to the collection of photoreceptor cells that innervate a ganglion (1st order neuron)?
The receptive field.
What kind of synapses do the photoreceptors have with 1st order neurons (ganglions)?
Inhibitory and excitatory synapses.
