vision and the eye Flashcards
what is the stimulus for vision?
electromagnetic energy or light waves
what is the lens?
elastic structure that changes to help focus
when the lens becomes thinner, it is focusing on objects that are?
far away/more distant
what is the retina?
a multi-layered structure at the back of the eye that contains light-sensitive photoreceptors
what is the function of the retina?
light-sensitive photoreceptors transduce light into electrical impulses
what is the cornea?
transparent protective structure at the front of the eye
what is the pupil?
and adjustable opening behind the cornea
what is the function of the pupil?
controls the amount of light that enters the eye through iris muscles
when pupils dilate, they? when pupils constrict, they?
get bigger; get smaller
what does your ability to see clearly depend on?
being able to accurately focus an image directly into your retina
what is myopia? people with myopia have difficulty seeing?
nearsightedness; difficulty seeing far away objects
what is hyperopia? people with hyperopia have difficulty seeing?
farsightedness; difficulty seeing up close objects
what are the two types of light sensitive cells found in the retina?
rods and cones
what are rods?
photoreceptors that contribute to black and white vision and are more sensitive to light then cones
what is the fovea?
the center of the retina that increases in concentration through the periphery of the retina
what are cones?
contribute to perception of color and detail and functions best in high illumination
what does the fovea only contain?
cones!
what are bipolar cells?
receive signals from rods and cones to form a synapse with them
which light sensitive cells is typically connected to bipolar cells?
rods! greater sensitivity to light
what do the ganglion cells do?
form a synapse with the bipolar cell
the axons of the ganglion cell form the?
optic nerve
what is the pathway of transduction?
rods/cones –> bipolar cells –> ganglion cells –> optic nerve
what cells modulate the signals of transduction?
horizontal and amacrine
what are photopigments?
protein molecules in the retina
what is the reaction of photopigments critical for?
visual transduction
photopigments undergo what type of reaction to transduce a light signal into neural code?
isomerization
photopigment cells need time to?
regenerate
what is the blind spot
axons that form the optic nerve create a blind spot with no photoreceptors
what are dark adaptations?
the progressive improvement of brightness sensitivity in low lighting conditions
the process of dark adaptation revolves around?
changes in the proportion of photopigments that are ready to transduce light to used photopigments in the process of regenerating
do rods or cones take longer to regenerate?
rods
what is pigment bleaching?
being temporarily ‘blinded’ by a bright light because the photopigment supply is depleted and must regenerate before transduction can occur again
how many types of photopigment do rods have?
one
what color of photopigment are rods most sensitive to?
blue (shortest wavelength)
