Special Senses Flashcards
_ percent of all sensory receptors are in the eyes
70 %
each eye has over _ nerve fibers
a million
most of the eye is enclosed in _
a bony orbit
a cushion of _ surrounds most of the eye
fat
_ meet at the medial & lateral commissure (_)
eyelids, (canthus)
_ are tarsal glands that produce an oily secretion that lubricates the eye
eyelashes
_ is a membrane that lines the eyelids
conjunctiva
_ connects to the outer surface of the eye
conjunctiva
_ secretes mucus to lubricate the eye & keep it moist
conjunctiva
_= lacrimal gland + ducts
lacrimal appartatus
_ produces lacrimal fluid; situated on the lateral aspect of each eye
lacrimal gland
_- drain lacrimal fluid from eyes medially
lacrimal caniliculi
_- provides passage of lacrimal fluid towards nasal cavity
lacrimal sac
_- empties lacrimal fluid into the nasal cavity
nasolacrimal duct
protects, moistens, & lubricates the eye
lacrimal apparatus
empties into the nasal cavity
lacrimal apparatus
Tears are a.k.a…
lacrimal secretions
Lacrimal secretions contain: (4 things)
mucus, antibodies, dilute salt solution, lysozyme
an enzyme that destroys bacteria
lysozyme
How many muscles attach to the outer surface of the eye?
6 muscles
extrinsic eye muscles produce what?
produce eye movements
the 3 layers that form the wall of the eyeball
Fibrous layer (outside), Vascular layer (middle), Sensory layer (inside)
white connective tissue area of eye
sclera
seen anteriorly as the ‘white of the eye’
sclera
transparent, central anterior portion of eye
cornea
allows for light to pass through
cornea
repairs itself easily
cornea
the only human tissue that can be transplanted without fear of rejection
cornea
a blood-rich nutritive layer in the posterior of the eye
choroid
pigments prevents light from scattering
choroid
modified anteriorly into 2 structures
vascular layer
smooth muscle attached to lens
ciliary body
regulates amount of light entering eye
iris
pigmented layer that gives eye color
iris
rounded opening in the iris
pupil
2 layers of the retina
outer pigmented layer & inner neural layer
which layer contains receptor cells (photoreceptors)
sensory layer
what are the 2 receptor cells?
rods & cones
sclera & cornea are in which layer?
fibrous layer
choroid, ciliary body, iris, & pupil are in which layer?
vascular layer
retina, rods & cones are in which layer?
sensory layer
signals pass from photoreceptors via a _?
a two-neuron chain
signals pass from the photoreceptors via a _, in which layer?
sensory layer
which 2 neurons are a part of the 2 neuron chain in the sensory layer?
bipolar neurons, ganglion cells
signals leave the retina toward the _ and through the _
toward the brain and through the optic nerve
where the optic nerve leaves the eyeball
optic disc (blind spot)
cannot see images focused on the _
optic disc
neurons of the retina & vision are in which layer?
sensory layer
most are found towards the edges of the retina
rods
allow dim light vision & peripheral vision
rods
all perception is in gray tones
rods
allow for detailed color vision
cones
densest in the center of the retina
cones
lateral to blind spot
fovea centralis
area of the retina with only cones
fovea centralis
visual acuity (sharpest vision) is here
fovea centralis
no photoreceptor cells are at the _
optic disc
biconvex crystal-like structure
lens
held in place by a suspensory ligament attached to the ciliary body
lens
anterior to the lens
anterior (aqueous) segment (chamber)
contains aqueous humor
anterior segment
anterior chamber aka…
aqueous chamber
posterior to the lens
posterior (vitreous) segment (chamber)
contains vitreous humor
posterior segment
posterior segment aka…
vitreous chamber
a way to get nutrients to the cells that are constantly regenerating
aqueous humor
watery fluids found bw lens & cornea
aqueous humor
similar to blood plasma
aqueous humor
helps maintain intraocular pressure *
aqueous humor & vitreous humor
aqueous humor is a part of which segment?
anterior segment
provides nutrients for the lens & cornea *
aqueous humor
reabsorbed into venous blood through the scleral venous sinus, or canal of Schlemm
aqueous humor
gel-like substance posterior to the lens
vitreous humor
vitreous humor is a part of which segment?
posterior segment
prevents the eye from collapsing
vitreous humor
light must be focused to a point on the _ for optimal vision
retina
the eye is set for _ vision
distance vision
distance vision is about how many feet?
over 20 feet away
the lens must change shape to focus on closer objects (less than 20 feet away), what is this called?
accomodation
images formed on the retina are called:
real images
what is reversed from left to right, upside down, & smaller than the object?
real images
location where the optic nerves cross
optic chiasma
fibers from the medial side of each eye cross over to the opposite side of the brain, what is this called?
optic chiasma
contain fibers from the lateral side of the eye on the same side & the medial side of the opposite eye
optic tracts
name an eye reflex
photopupillary reflex
internal muscles are controlled by which system?
the autonomic nervous system
bright light causes pupils to constrict through the action of which 3 muscles?
radial, circular, & ciliary muscles
in response to focusing on a near object, then looking at distant object (and vice versa)
accommodation (reflex)
_ muscles control eye movement to follow objects
external muscles
viewing close objects causes _
convergence (eyes moving medially)
eye focuses images on the retina properly
emmetropia
Myopia is _sighted
nearsighted
distant objects are blurry, what is this called?
myopia
light from those objects fails to reach the retina & are focused in front of it
myopia
results from an eyeball that is too long
myopia
hyperopia is _sighted
farsighted
near objects appear blurry while distant objects are clear
hyperopia
distant objects are focused behind the retina
hyperopia
results from an eyeball that is too short or from a “lazy lens”
hyperopia
images are blurry, results from focusing as lines, not points, on the retina due to unequal curvatures of the cornea or lens
astigmatism
inhibited rod function that hinders the ability to see at night
night blindness
genetic conditions that result in the inability to see certain colors
color blindness
due to the lack of 1 type of cone
(partial) color blindness
when lens becomes hard & opaque, our vision becomes lazy & distorted
cataracts
can cause blindness due to increasing pressure within the eye
glaucoma
loss of the same side of the visual field of both eyes; results from damage to the visual cortex on one side only
hemianopia
instrument used to illuminate the interior of the eyeball
ophthalmoscope
can detect diabetes, arteriosclerosis, degeneration of the optic nerve & retina
ophthalmoscope
night blindness, color blindness, & cataracts are all what?
homeostatic imbalances of the eyes
glaucoma, & hemianopia are both what?
homeostatic imbalances of the eyes
