The photoreceptors are responsible for changing light into impulses that are sent to the brain. A term used to describe a molecule or material that responds to light. Hole in the center of the iris, through which the light enters. Can be either round, as in humans, or slit-shaped, as in many nocturnal animals. The innermost layer of the eyeball.
Light is imaged onto the retina by the lens.
The retina contains three layers of neurons, including the photoreceptor neurons. The other neurons in the retina are responsible for sending impulse signals to the brain. A protein found in the membrane of rod cells that is responsible for the absorption of light, thus leading to our ability to see. Rod cells are responsible for seeing at low light levels. The light interacts with the molecule to excite either the molecule's motions or electrons.