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Chp2Vision
Anatomical function of eye
61
Psychology
Undergraduate 3
02/06/2013

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Term
Wave
Definition
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.
Term
Photon
Definition
A quantum of visible light or other form of electromagnetic radiation demonstrating both particle and wave properties.
Term
Absorb
Definition
To take up light, noise, or energy and not transmit it at all.
Term
Scatter
Definition
To disperse light in an irregular fashion.
Term
Reflect
Definition
To redirect something that strikes a surface, especially light, sound, or heat.. usually back toward its point of origin.
Term
Transmit
Definition
To convey something (e.g. light) from one place or thing to another.
Term
Refract
Definition
1. To alter the course of a wave of energy that passes into something from another medium, as water does to light entering it from the air. 2. To measure the degree of refraction in a lens or eye.
Term
Image
Definition
A picture or likeness.
Term
Cornea
Definition
The transparent "window" into the eyeball.
Term
Transparent
Definition
Allowing light to pass through with no interruption, so that objects on the other side can be clearly seen.
Term
Aqueous humor
Definition
The watery fluid in the anterior chamber of the eye, just behind the cornea but in front of the lens.
Term
Crystalline Lens
Definition
The lens inside the eye that enable the changing of focus.
Term
Iris
Definition
The colored part of the eye, consisting of a muscular diaphragm surrounding the pupil and regulating the light entering the eye by expanding and contracting the pupil.
Term
Vitreous humor
Definition
The transparent fluid that fills the vitreous chamber in the posterior part of the eye.
Term
Retina
Definition
A light-sensitive membrane in the back of the eye that contains rods and cones, which receive an image from the lens and send it to the brain through the optic nerve.
Term
Accommodation
Definition
The process by which the eye changes its focus (in which the lens gets fatter as gaze is directed toward nearer objects).
Term
Presbyopia
Definition
literally "old sight". The loss of near vision because of insufficient accommodation.
Term
Cataract
Definition
An opacity of the crystalline lens.
Term
Emmetropia
Definition
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.
Term
Myopia
Definition
Nearsightedness, a common condition in which light entering the eye is focused in front of the retina and distant objects cannot be seen sharply.
Term
Hyperopia
Definition
Farsightedness, a common condition in which light entering the eye is focused behind the retina and accommodation is required in order to see near objects clearly.
Term
Transduce
Definition
To convert from one form of energy to another (e.g. from light to neural electrical energy, or from mechanical movement to neural electrical energy.)
Term
Fundus
Definition
The back layer of the retina, what the eye doctor see through an ophthalmoscope.
Term
Photoreceptor
Definition
A light sensitive receptor in the retina.
Term
Rod
Definition
A photoreceptor specialized for night vision.
Term
Cone
Definition
A photoreceptor specialized for daylight vision, fine visual acuity, and color.
Term
Duplex
Definition
In reference to the retina, consisting of two parts: the rods and cones, which operate under different conditions.
Term
Outer Segment
Definition
The part of a photoreceptor that contains photopigment molecules.
Term
Inner Segment
Definition
The part of a photoreceptor that lies between the outer segment and the cell nucleus.
Term
Synaptic terminal
Definition
The location where axons terminate at the synapse for transmission of information by the release of a chemical transmitter.
Term
Chromophore
Definition
The light-catching part of the visual pigments of the retina.
Term
Rhodopsin
Definition
This visual pigment found in rods.
Term
Melanopsin
Definition
A photopigment that is sensitive to ambient light.
Term
Photoactivation
Definition
Activation by light.
Term
Hyperpolarization
Definition
An increase in membrane potential such that the inner membrane surface becomes more negative than the outer membrane surface.
Term
Graded potential
Definition
An electrical potential that can vary continuously in amplitude.
Term
Eccentricity
Definition
The distance between the retinal image and the fovea.
Term
aging-related macular degeneration (AMD)
Definition
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 two forms of AMD: wet and dry.
Term
Macula
Definition
The central part of the retina that has a high concentration of cones.
Term
Fovea
Definition
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.
Term
Scotoma
Definition
A blind spot in the visual field.
Term
Horizontal cell
Definition
A specialized retinal cell that contacts both photoreceptor and bipolar cells.
Term
Lateral inhibition
Definition
Antagonistic neural interaction between adjacent regions of the retina.
Term
Amacrine cell
Definition
A retinal cell found in the inner synaptic layer that makes synaptic contacts with bipolar cells, ganglion cells, and other amacrine cells.
Term
Bipolar cell
Definition
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.
Term
Diffuse bipolar cell
Definition
A bipolar retinal cell whose processes are spread out to receive input from multiple cones.
Term
Sensitivity
Definition
1. The ability to perceive via the sense organs. 2. Extreme responses to radiation, especially to light of a specific wavelength. 3. The ability to respond to transmitted signals.
Term
Visual acuity
Definition
A measure of the finest detail that can be resolved by the eyes.
Term
Midget bipolar cell
Definition
A small bipolar cell in the central retina the receives input from a single cone.
Term
ON bipolar cell
Definition
A bipolar cell that responds to an increase in light captured by the cones.
Term
OFF bipolar cell
Definition
A bipolar cell that responds to a decrease in light captured by the cones.
Term
Ganglion cell
Definition
A retinal cell that receives visual information from photoreceptors via two intermediate neuron types (bipolar and amacrine cells) and transmits information to the brain and midbrain.
Term
P ganglion cell
Definition
A small ganglion cell that receives excitatory input from single midget bipolar cells in the central retina and feeds the parvocellular layer of the lateral geniculate nucleus.
Term
M ganglion cell
Definition
A ganglion cell resembling a little umbrella that receives excitatory input from diffuse bipolar cells and feeds the magnocellular layer of the lateral geniculate nucleus.
Term
Koniocellular cell
Definition
A neuron located between the magnocellular and parvocellular layers of the lateral geniculate nucleus. This layer is known as the konioncellular layer.
Term
Receptive field
Definition
The region on the retina in which visual stimuli influence a neuron's firing rate.
Term
ON-center cell
Definition
A cell that depolarizes in response to an increase in light intensity in its receptive-field center.
Term
OFF-center cell
Definition
A cell that depolarizes in response to a decrease in light intensity in its receptive-field center.
Term
Filter
Definition
An acoustic, electrical, electronic, or optical device, intrument, computer program, or neuron that allows the passage of some frequencies or digital elements and blocks the passage of others.
Term
Contrast
Definition
The difference in luminance between an object and the background, or between lighter and darker parts of the same object.
Term
Retinitis pigmentosa
Definition
A progressive degeneration of the retina that affects night vision and peripheral vision. RP commonly runs in families and can be caused by defects in a number of different genes that have recently that have recently been identified.
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