Module 4.2 - The Visual System Flashcards
light travels in waves that vary in terms of 2 different properties. what are these 2 properties?
length and amplitude
true or false: different species see different wavelength
true
what are the 3 characteristics of light
wavelength, amplitude, purity
in what 3 ways are the characteristics of light experienced by us?
hue, intensity and saturation
hue
colour of the spectrum
intensity
brightness
saturation
colourfullness or density
sclera
the white, outer surface of the eye
cornea
the clear layer that covers the front portion of the eye and also contributes to the eyes ability to focus
pupil
regulates the amount of light that enters by changing its size; it dilates (expands) to allow more light to enter and constricts (shrinks) to allow less light into the eye
iris
a round muscle that adjusts the size of the pupil; it also gives the eyes their characteristic colour
lens
a clear structure that focuses light onto the back of the eye
how does the lens focus light onto the back of the eye?
through the process of accommodation
retina
lines the inner surface of the eye and consists of specialized receptors that absorb light and send signals related to the properties of light to the brain
true or false: the retina consists of a single layer
FALSE: the retina contains a number of different layers
photoreceptors
specialized receptors found at the back of the eye; they send information to biopolar and ganglion cells
optic nerve
a dense bundle of fibres that transmit activity from the ganglion cells to the brain
optic disc
an area on the retina with no photoreceptors
blind spot
area on the retina with no photoreceptors
why are we not aware of our blind spot?
because the mind “fills in” the blind spot
rods
photoreceptors that occupy peripheral regions of the retina; they are highly sensitive under low light levels
what colours are rods most responsive to?
black and grey
what is the ratio of rods to ganglion cells?
10:1
cones
photoreceptors that are sensitive to the different wavelengths of light that we perceive as colour