Chapter 10 Pt. 2 (Part 1) Flashcards
what is the significance of the fovea?
straight back
high cone density = higher acuity, accuracy
cones = color
what is the significance of the optic disk of the eye?
no image can be created but the brain fills it in
how does the eye refract light in order to focus on distant and near objects? (focal point)
changes focal point by
FAR OBJECT:
ciliary muscle: relaxed
zonular fibers: tight
lens: big
NEAR OBJECT:
ciliary muscle: contracted
zonular fibers: slack
lens: smaller
what is the role of the cornea in focusing?
refractive ability remains constant because the cornea curvature cannot be changed
what is the role of the lens in focusing?
refractive ability can be altered by changing the curvature of the lens to focus
what is the role of the ciliary muscle in focusing?
change refractive index of lens
what is the role of the zonular fibers in focusing?
change refractive index of lens
when light from an image hits the back of the eye, the image is actually upside down, but we don’t see everything upside down. why?
our brain corrects the image
what do rods and cone cells have in common?
they are photoreceptors that contain photopigment
what is photopigment? aka what does it do?
absorb light
what cells serve as connector neurons to link photoreceptors and retinal ganglion cells?
bipolar cells
what is the role of bipolar cells?
serve as connector neurons to link photoreceptors and retinal ganglion cells
what do horizontal cells do?
modulate photoreceptor stimulation of bipolar cells
modulate photoreceptor stimulation of bipolar cells
horizontal cells
what do amacrine cells do?
modulate bipolar cell stimulation of retinal ganglion cells
modulate bipolar cell stimulation of retinal ganglion cells
amacrine cells
retinal ganglion cells are the only neural cells in the eye that can generate ____, all the others only fire ____. why?
AP
graded potentials
no voltage-gated Na+ channels
what is the advantage of dilating the pupils?
lets more light into the eye. more light means you can interpret the environment better
what is the definition of refraction? what is it used for?
bending light. to bring objects into focus.
increase lens curvature (thickness) makes the lens _____ in order to ?
more refractive
focus on near objects
decrease lens curvature (thickness) makes the lens ____ in order to ?
less refractive
focus on distant objects
how to focus on near objects?
increase lens curvature
how to focus on far objects?
decrease lens curvature. relaxed ciliary muscle is default.
what is near-sightedness
lens bends light in too much
what is far-sightedness
lens can’t bend light in enough
what is astigmatism
light gets focused at multiple sites on the retina
what cell released GABA when depolarized?
horizontal and amacrine cells
horizontal cells modulate ___ potentials sent from _____ to _______
graded potentials
photoreceptors
bipolar cells
what do rods have that make them more sensitive to light?
larger outer segment
what is the significance of a larger outer segment in rods?
more sensitive to light
what is the significance of the smaller outer segment in cones?
less sensitive to light
what makes cones less sensitive to light
smaller outer segment
