Chapter 3 Pt. 1-2 Flashcards
vision is based on what type of energy
visible light (light energy or photons from the environment)
electromagnetic spectrum
electrical energy spreading microscopic waves
most perceived light comes from reflected light and show colors based on electromagnetic spectrum
wavelengths
distance between peaks of electromagnetic waves
visible light to humans (in nm)
400 to 700 nm
color of shorter wavelengths
blue
color of medium wavelengths
green
color of longer wavelengths
yellow / orange / red
pupil
an opening for light to enter
iris
muscle that can make pupil dilate or constrict
cornea
nonadjustable clear part covering the front
80% of where images are focused
lens
adjustable to deal with distance
20% if where images are focused
ciliary muscles
help shape the lens to focus on far and close objects
changes the lens
retina
back of the eye containing rods and cones
optic nerve
sends electrical signals to the brain
rods
represent photoreceptors
large, cylinder shape
cones
represent photoreceptors
small, cone-like
what is the outer segment of the retina?
visual pigments
visual pigments
react to light and create electrical signals to optic nerve
chemical for colors
fovea
aka macula
small area containing only cones
the area that you look directly at is where fovea is located
photoreceptor distribution in fovea
50,000 cones
peripheral retina
outside of fovea
contains more rods than cones
photoreceptor distribution in peripheral retina
120 mil rods
6 mil cones
macular degeneration
when fovea is destroyed, people are unable to see the direct center (only) of what they are looking at
reitinitis pigmentosa
poor peripheral vision
degeneration of retina passed on from one generation to another
in severe cases, not only do rods get attacked but cones in fovea do too, causing blindness
blind spot
area where there is absence of retina and visual receptors
located near optic nerve
why is our blind spot not noticeable? review demos (fig. 3.7 and 3.8 on p. 43)
it is off the visual field where objects aren’t sharply focused
brain fills in the blind spot
accommodation
unconscious adjustment of lens’s shape to focus image
what happens to lenses when ciliary muscles tighten?
lens bend (thicker curvature)
focus on near object
what happens to lenses when ciliary muscles relax?
lens flatten (thinner curvature)
focus on far objects
near point
point at which a close object can precisely reach the retina so that it can be seen clearly
far point
point at which a far object can precisely reach retina so that it can be seen clearly
refractive errors
is accommodation foolproof? why?
presbyopia
myopia
two possible problems for myopia
hyperopia
how do photoreceptors process light energy?
transduction
what are visual pigment molecules and where are they located?
molecule
two parts of a visual pigment molecule
isomerization (+ what happens when it occurs?)
dark adaptation
threshold
sensitivity
three adaptation curves
visual pigment bleaching
visual pigment regeneration
how long do cones and rods regenerate their pigments?
two important relationships between perception and physiology when examining visual pigment regeneration
