7.6 Flashcards
The wavelengths of light capable of stimulating the receptors of the eye are between about 400 and 750 nm. These are collectively known as the ___ ___.
visible spectrum
The opening in the iris that allows light into the eye is the ___.
pupil
When a light ray passes from air into water its direction changes, a phenomenon called ___.
refraction
Which of the following cells provide lateral integration between neurons in the retina?
- amacrine cells
- horizontal cells
Because of the shapes of their light-sensitive outer segments, the two types of photoreceptors are called ___ and ___.
rods; cones
Vision is the perception of ___.
electromagnetic raditation
A photoreceptor cell that is extremely sensitive and is responsible for night vision is the ___ cell.
rod
When a ray of light enters the cornea perpendicular to the cornea’s surface ___.
it passes straight into the cornea without changing its direction of travel
Rod cells of the retina have a unique photopigment called ___.
rhodopsin
The correct order of the structures in the figure, beginning with the front of the retina on the far left to the optic nerve fibers on the far right is ___.
choroid, photoreceptor cells, horizontal cells, bipolar cells, amacrine cells, ganglion cells
In dim light, rods are ___ cones.
more active than
In the neural pathway of vision, the first cells where action potentials can be initiated are the ganglion cells, because these are the only cells in the pathway that ___ ion channels.
posses voltage-gated
Put the layers of the retina in the order that light passes through them.
- ganglion cells
- bipolar cells
- photoreceptor cells
Visual signals from the left half of the visual field travel to the ___ lateral geniculate nucleus of the thalamus.
right
Axons of ganglion cells in both retinas assemble to form the ___ nerves.
optic
When light strikes the retina and initiates action potentials that travel to the visual cortex, the first cell type that undergoes an action potential is a(n) ___ cell.
ganglion
The back layer of the retina, closest to the choroid, is composed of the ___ (rods and cones), while the front layer consists of the ___ cells, whose axons become the optic nerve.
photoreceptors; bipolar
the axons of ___ cells make up the optic nerve.
ganglion
The colors we perceive are related to the wavelengths of light that the ___ in the objects of our visual world reflect, absorb, or transmit.
pigment
Which statements are true of the condition known as color blindness?
- it occurs mostly in men
- two cone photopigments are coded for by the X chromosome
___ are small, jerking movements of the eyeball that rapidly bring it from one fixation point to another.
saccades
___ refers to the clouding of the lens caused by lifelong accumulation of precipitated proteins.
cataract
Which of the following cells provide lateral integration between neurons in the retina?
- horizontal cells
- amacrine cells
Objects that absorb all wavelengths of light are perceived as the color ___, while those that reflect a mixture of all wavelengths of light are perceived as the color ___.
black; white
A defect in genes encoding cone photopigments can cause a condition known as ___ ___.
color blindness
T/F: Saccades move the visual image over the retina to prevent bleaching and adaptation of the photoreceptors.
T (Saccades do move the visual image over the receptors, thereby preventing adaptation that would result from persistent photobleaching of photoreceptors in a given region of the retina.)
An object appears red because it absorbs ___ wavelengths, while simultaneously reflecting the ___ wavelengths.
shorter (blue); longer (red)
