3.2 Vision: seeing the light Flashcards
(20 cards)
Cornea
A transparent covering on the eyes surface through which light enters.
Iris
The pigmented, circular muscle in the eye that regulates the size of the pupil to adjust to changes in the level of illumination.
Pupil
The black opening inside the iris that allows light to enter the eye.
Lens
The structure in the eye that focuses light rays on the retina.
Accomidation
The process by which the lens changes its shape to focus images more clearly on the retina.
Retina
The light sensitive layer of the inner surface of the eye that contains photoreceptor cells.
Photoreceptors
Light sensitive cells (rods and cones) in the eye upon which light registers
rods
Photoreceptors that are sensitive only to the intensity of light. ( Shades of light and dark)
cones
Photoreceptors that are sensitive to color.
Bipolar cells
A layer of interconnecting cells in the eye that connect photoreceptors to ganglion cells.
Ganglion cells
Nerve cells in the back of the eye that transmit neural impulses in response to light stimulation, the axons which make up the optic nerve.
Optic nerve
The nerve that carries neural impulses generated by light stimulation from the eye to the brain.
Blind spot
The area in the retina where the optic nerve leaves the eye and that contains no photoreceptor cells.
Fovea
The area near the center of the retina that contains only cones and that is the center of focus for clearest vision.
Feature detectors
Specialized neurons inn the visual cortex that respond only to particular features of visual stimuli, such as horizontal or vertical lines.
trichromatic theory
A theory of color vision that posits that the ability to see different colors depends on the relative activity of three types of color receptors in the eye (red, green, and blue violet.
Afterimage
The visual image of a stimulus that remains after the stimulus is removed.
Trichromats
People with normal color vision who can discern all the colors of the visual spectrum
Monochromats
People who have no color vision and can see only in black and white
Dichromats
People who can see some colors but not others.