Vision Flashcards
What is the cornea?
Transparent surface that covers the pupil and iris
What is the sclera?
The white bit of the eye
What is the purpose of the lens?
To focus light rays on the retina (mine sucks because I need glasses)
What is the retina?
The internal lining of the rear 2/3 of the eye
What is the purpose of the retina?
To convert light energy into electrical impulses/neural activity
What is the macula?
The central area of the retina, it’s specialized for central vision
What is the fovea?
The center of the macula and retina, where the image is least distorted
What is the optic nerve made out of?
The axons of retinal ganglion cells
Where are the extraocular muscles located that enable the eye to move?
The sclera
What is light?
Electromagnetic energy emitted in the form of waves - different wavelengths appear as different colours
Which wavelengths of light are visible to the human eye?
400 - 700 nm
The flow of visual information within the retina
Photoreceptors to the bipolar cells to the ganglion cells
Two types of photoreceptors and their purpose
Rods: good for dim light (1000x more sensitive to light than cones)
Cones: good for color, transmit most of the visual information in bright light
Which kind of photoreceptors have the highest concentration in the fovea?
Cones! Rods are more common in the peripheral retina
What makes different cones sensitive to different wavelengths of light to enable colour vision?
Variations in photopigments (all rods have the same photopigment)
What are photosensitive retinal ganglion cells (pRGC)?
Sensitive to blue light, essential for circadian rhythm! (blue light is associated with morning)
Which has lower convergence and resulting higher acuity, rods or cones?
Cones!
Which three color frequencies can the cones in the human eye identify?
Blue, red, and green
What is the opponent process theory? How is it explained?
Color perception is controlled by the activity of two opponent systems (blue/yellow or red/green)
We never see certain color combinations, such as redish-green or yellowish-blue
Where is the blind spot located?
In the temporal hemiretina, where the retinal ganglion cells exit the retina (optic nerve)
What’s the difference between NT-gated K+ and Na+ channels?
NT-gated K+ channels: K+ moves out, causes hyperpolarization and is therefore inhibitory
NT-gated Na+ channels: Na+ moves in, causes depolarization and is therefore excitatory
Which types of cells carry information from your eyes to your brain?
Retinal ganglion cells