Chapter 2: Light and Vision-Vocab Flashcards
Wave
An oscillation that travels through a medium by transferring energy from one particle or point to another without causing any permanent displacement of the medium.
photon
A quantum of visible light or other form of electromagnetic radiation demonstrating both particle and wave properties.
absorb
To take up light, noise, or energy and not transmit them at all.
scatter
to disperse light in an irregular fashion.
accommodation
The process by which the eye changes its focus (in which the lens gets fatter as gaze is directed toward nearer objects).
aging-related macular degeneration (AMD)
A disease associated with aging that affects the macula. AMD gradually destroys sharp central vision, making it difficult to read, drive, and recognize faces. There are two forms of AMD: wet and dry.
amacrine cell
A retinal cell found in the inner synaptic layer that makes synaptic contacts with other cells of its kind, as well as bipolar cells and ganglion cells.
aqueous humor
The watery fluid in the anterior chamber of the eye.
astigmatism
A visual defect caused by the unequal curving of one or more of the refractive surfaces of the eye, usually the cornea.
bipolar cell
A retinal cell that synapses with either rods or cones (not both) and with horizontal cells, and then passes the signals on to ganglion cells.
cataract
An opacity of the crystalline lens.
chromophore
The light-catching part of the visual pigments of the retina.
cone
A photoreceptor specialized for daylight vision, fine visual acuity, and color.
contrast
The difference in luminance between an object and the background, or between lighter and darker parts of the same object.
cornea
The transparent “window” into the eyeball.
crystalline lens
The lens inside the eye that enables the changing of focus.
diffuse bipolar cell
A bipolar retinal cell whose processes are spread out to receive input from multiple cones.
duplex
In reference to the retina, consisting of two parts: the rods and cones, which operate under different conditions.
eccentricity
The distance between the retinal image and the fovea.
emmetropia
The condition in which there is no refractive error, because the refractive power of the eye is perfectly matched to the length of the eyeball.
filter
An acoustic, electrical, electronic, or optical device, instrument, computer program, or neuron that allows the passage of some frequencies or digital elements and blocks the passage of others.
fovea
A small pit, near the center of the macula, that contains the highest concentration of cones, and no rods. It is the portion of the retina that produces the highest visual acuity and serves as the point of fixation.
fundus
The back layer of the retina—what the eye doctor sees through an ophthalmoscope.
ganglion cell
A retinal cell that receives visual information from photoreceptors via two intermediate neuron types (bipolar cells and amacrine cells) and transmits information to the brain and midbrain.
graded potential
An electrical potential that can vary continuously in amplitude.