Chapter 16A (eye) Flashcards
what is refraction
the light waves being bent
what are the three places that refraction occurs in the eye
going into the cornea, as they enter the lens, and as they exit the lens.
what is the goal of refraction
to allow the the light waves to converge on the retina.
what are cataracts
clouding of the crystallins
what is accommodation
when the lens fattens up as a result of ciliary zonules becoming slack.
During accommodation the zonules will __ and the ciliary muscle __.
slack, contracts
As the ciliary muscle contracts it __ the lens.
reaches closer to
__ is used when looking at something 20 feet or more away.
Emmetropia
The light rays coming towards your cornea are ___coming to the cornea in emmetropia
running parallel
With accommodation closer than 20 ft away are the light rays parallel or converging?
converging
is the lens flat or bulging during accommodation closer than 20 feet
bulging
The __ is taking the light waves in then refracting them and converge them at the__
cornea, retina.
When looking at something from far away the __ system is engaged.
sympathetic
__ is when the eyes medially rotate.
`Convergence
The retina is called the ___because that’s where it has all of the __
neural layer, photoreceptors.
why is the optic disc called the blind spot
because there are no photoreceptors
The photoreceptors are farthest back in the retina in the__
pigmented layer.
Rods __ in the dark and when this happens you cannot see.
depolarize
As rods are depolarizing they are inhibiting the __. In order for ___ to depolarize the photoreceptors need to __.
bipolar cells, bipolar cells, hyperpolarize
__ cells are the second order neurons in a visual pathway the __ cells are the first order.
Ganglion, bipolar
The optic nerve is formed by __ cells.
ganglion
If you want to see something you want your rods to __so the bipolar cells can ___where they will release excitatory neurotransmitters.
hyperpolarize, depolarize
The outer segment of rods and cones are where you find __
photopigments.
__is found in rods and is a combination of opsin and retinol.
Rhodopsin
The photopigment in a cone is called __
photopsin.
Different __of light is what translates color.
wavelengths
__ give you color vision because they respond to different wavelengths of light.
Cones
__are the only ones that can function in a low light situation.
Rods
Rods are mostly found in the ___ while the cones are clustered around the ___
periphery of the retina, macula lutea and fovea centralis.
Phototransduction means __
changing light energy or changing light to vision
In the dark the rods are __which gives poor vision
depolarizing
In the dark rhodopsin is __
not absorbing light
___ is what’s responsible for the hyperpolarization of the rods.
The breakdown of rhodopsin
In the dark the rods are __ and the bipolar cells are __
depolarizing, hyperpolarizing
can you see while the rods are depolarizing and bipolar cells are hyper polarizing?
no
In the light cis-retinol straightens out to__. Then ___and ___ split.
trans-retinol, trans-retinol, opsin
what causes rods to hyper polarize in the light
the split of trans-retinol and opsin.
what happens after the hyper polarization of the rod in the light?
glutamate which is inhibitory in the eyes is released
glutamate is __ in the eyes but usually __ everywhere else.
inhibitory, excitatory
Optic tracts send fibers to the__
corpora quadrigemina.
The __ run along the margin of the eyelid and anchor the levator palpebrae superioris muscle.
tarsal plates
The__ secrete oil to prevent dry eye and keep the eyelashes from sticking together.
tarsal glands
The lacrimal caruncle contains __ glands in the medial commissure.
sebaceous and sweat
__ is a transparent mucous membrane that covers the anterior sclera and produces lubricating mucous.
Conjunctiva
is the Conjunctiva present in the region of the cornea?
no
what is conjunctivitis
pink eye
The __produces tears containing mucus, antibodies, and lysozyme to cleanse and moisten the eye.
lacrimal apparatus
where do the tears drain into?
the lacrimal puncta→ lacrimal canals→ nasolacrimal duct→ nasal cavity.
The __ is filled with aqueous humor that forms and drains continuously, supplying nutrients and oxygen to the__
anterior segment, lens and cornea.
__ is when the aqueous humor does not drain and rising pressure can damage the retina and optic nerve.
Glaucoma
what separates the anterior and posterior chamber?
the iris
In the posterior segment the vitreous humor does what?
transmits light, supports the lens and retina, and helps maintain the shape of the eyeball.
The__of the eyeball is the outer most layer composed of __
fibrous tunic, dense collagenous connective tissue.
The ___ protects the shape of the eyeball and anchors the muscles.
sclera
The __is the transparent layers of stratified squamous epithelium and contains pain receptors.
cornea
The __ is the only tissue in the body that can be transplanted from one person to another with little or no possibility of rejection.
cornea
The __ contains the iris which is a dual layer smooth muscle organ that regulates light entry
vascular tunic
The__ is a vascular pigmented layer at the back of the eyeball that prevents the scattering of light within the eye.
choroid
The __ is the ring of smooth muscles which attach to the lens by suspensory ligaments (ciliary zonules)
ciliary body
The nervous tunic is comprised of the __
retina.
As light is reflected off of objects it travels to our eyes and is refracted by what three structures
entering the cornea, entering the lens, exiting the lens.
__ allows the lightwaves to converge at a focal point.
refraction
The __ is a transparent, flexible structure which can change shape in order to focus light on the retina.
lens
the lens is composed of layers of lens epithelium which contain __
protein crystallins.
what are cataracts
clouding of the lens
what is presbyopia
the decreased elasticity of the lens.
When the ciliary body __the ciliary zonules become slack.
contracts
if the lens fattens, will that help you focus on images that are far away or close up?
close up
are light rays parallel or diverging in emmetropia
parallel
are light rays parallel or diverging in accommodation
diverging
is the lens fat or flat during emmetropia
flat
is the lens fat or flat during accommodation
fat
is the sympathetic or parasympathetic system used during emmetropia?
sympathetic
is the sympathetic or parasympathetic system used during accommodation
parasympathetic
what is accommodative pupillary reflex
the constriction of both pupils used during accommodation
what is convergence
the medial rotation of both eyeballs during accommodation
is emmetropia used for closer or farther than 20 feet vision
farther
is accommodation used for closer or farther than 20 feet vision
closer
what is astigmatism
the inability to simultaneously focus light rays that enter the eye on different planes. focusing on vertical lines may cause horizontal lines to go out of focus. caused by a deviation in the shape of the cornea so that it is shaped like the back of a spoon
what is hyperopia
farsightedness- a condition in which the eyeball is too short. the retina lies in front of the focal point of the lens
how can hyperopia be fixed
with convex lenses
what is myopia
nearsightedness- a condition in which the eyeball is too long
how can myopia be fixed
with concave lenses
what is presbyopia
the reduced ability to accommodate for near vision with age. it is caused by declining flexibility of the lens
how is presbyopia corrected
with bifocal lenses or reading glasses
The retina is the layer which contains photoreceptors specialized for __
converting light energy into nerve impulses
The optic nerve carries impulses from the __ to __
retina, the brain
The optic disc is the site of the optic nerve attachment but lacks __ and __
rods and cones.
__ is the neural layer that separates from the pigmented layer.
Retinal detachment
the __ blocks photoreceptors from nutrients
vitreous humor
what cell type contains photoreceptors responsible for low-light vision and non-color vision
rods,
what cell type contains photoreceptors responsible for bright-light vision and color vision
cones
what is the function of bipolar cells
they are first order neurons of the vision pathway
what is the function of ganglion cells
second-order neurons of the visual pathway and the axons form the optic nerve
what are the functions of horizontal cells and amacrine cells
they regulate connections between other cells of the retina and enhance and contrast and perception of vision
what do rods regulate
they depolarize in the dark and hyper polarize in the light
what do bipolar cells regulate
they depolarize when photoreceptors are hyperpolarized
what do ganglion cells regulate
they depolarize due to excitatory neurotransmitters from bipolar cells
the inner segment of rods and cones___
joins the cell body and contain mitochondria and other organelles
the outer segment of rods and cones__
contains photopigments which change shape as they absorb light.
Cones have photopsin which is able to respond to _ different light wavelengths.
3
Rods and cones are distributed throughout the __
retina.
In the dark the rods undergo an automatic __
depolarization.
Axons of retinal ganglion cells form the __
optic nerve.
Fibers of the optic nerves split at the __
optic chiasma.
Medial fibers of the optic nerve decussate at the __and the lateral fibers remain __
optic chiasma, ipsilateral
After the optic chiasma, most fibers of the optic tracts continue to the __. Other optic tract fibers send branches to the __ ending in the superior colliculi.
thalamus, midbrain
__ connect fibers from the thalamus to the primary visual cortex in the occipital lobes.
Optic radiation
Both eyes view the same images from slightly different angles. Vision is__, the left view is transmitted to the right occipital lobe.
contralateral
Depth perception results from __ of the slightly different images. Loss of an eye results in loss of depth perception.
cortical fusion
Damage to the optic chiasma, the optic tract, optic radiation or primary visual cortex can result in__
the loss of the entire contralateral visual field.
