Unit 8: The Eye Flashcards
electromagnetic energy
-a form of energy that includes light that is simultaneously both a wave and a particle
wavelength
-the distance between 2 adjacent peaks in a repeating wave; different forms of electromagnetic energy are classified by their wavelengths
field of view
-the part of the world you can see without eye movements
cornea
-clear front surface of the eye that allows light in; also a major focusing element of the eye
-rigid, so it can only focus on 1 distance
iris
-the colored part of the eye; a muscle that controls the amount of light entering through the pupil
pupil
-an opening in the middle of the iris
-dark, pupil dilates which lets more light in
-bright area means that the pupil gets smaller bringing less light in
lens
-the adjustable focusing element of the eye, located behind iris
retina
- the paper thin layer of cells at the back of the eye where transduction takes place
receptors
-transduce light into a neural signal
rods
night vision, light detection grayscale vision
-in the periphery
cones
high visual acuity, color vision, daytime vision
-in the fovea
horizontal cells
-receive information from photoreceptors and other horizontal cells; cross talk across photoreceptors
bipolar cells
-receive information from photoreceptor; send signals to retinal ganglion cells
amacrine cells
-receive information from bipolar cells and other marine cells; cross talk function
retinal ganglia
-receive information from bipolar cells; send signal to Brain via the optic nerve
optic disc
-the part of the retina where the optic nerve leaves the eye and heads to the brain; along the optic disc
photopigment
- a molecule that absorbs light and by doing so releases an electric potential by altering the voltage in the cell
-contained in discs within rods and cones
hyperpolarization
-a change in voltage of a neuron whereby the inside of the cell becomes more negative than in its resting state
duplex theory of vision
-2 distinct ways in which our eyes work, the photopic, associated with the cones, and the scotopic associated with the rods
The Photopic System
-vision associated with the cones; it is used in the daytime, has good acuity in the fovea and has color vision
The scotopic vision
associated with rods
receptive field
-a region of adjacent receptors that will alter the firing rate of a cell that is higher up in the sensory system
center-surround receptive field
-a receptive field
-the center of the field responds opposite to how the surround of the receptive field responds
-if the center responds with an increase of activity to light then the surround responds with a decrease in activity to light
on-center receptive field
-the center produces excitation, whereas the surround produces inhibition
off-center receptive field
- the center produces inhibition, whereas the surround produces excitation
myopia
-near sightedness
-can focus well on near objects
-problems in usually both eyes
-the eye tends to be too long from front to back for the lens
hyperopia
-a condition causing an inability to focus on near objects, also called farsightedness
-occurs because accommodation cannot make the lens thick enough
-focus behind retina
Astigmatism
-develops from an irregular shape of the cornea or an irregular shape of the lens
-impossible for the lens to accommodate a fully focused image
Cataracts
-clouding of the lens
-affect older adults
-due to water build up
-can lead to blindness
macular degeneration
-destroys the fovea and area around it
-occurs in 2 forms: wet and dry
-dry: takes years and no treatment
-wet: fast onset, less common, and partially treatable
Retinitis Pigmentosa
- inherited progressive degenerative disease of the retina that may lead to blindness
-tunnel vision
