Question | Answer |
sclera | s: dense fibrous CT "white" part of eye
f: stabilizes shape of eye during movement by muscles |
cornea | s: transparent area anterior surface of eye composed of dense matrix of multiple collagen fiber layers
f: permits passage of light & curvature aids focusing process |
choroid | s: cascular layer covered by sclera
f: capillary network delivers 02 & nutrients to tissue within neural tunic |
ciliary body | s: thickened region bulges into interior its ligaments extend to lens
f: supports the lens & controls its shape behind the pupil |
iris | s: colored part contains blood vessels, pigament cells, & layers of smooth muscle fibers
f: changes the diameter of the pupil with muscle fibers |
retina | outer pigmented layer contains photo-receptors
inner nervous tissue layer contains supporting cells & neurons that perform preliminary processing & integration of visual info |
photoreceptors | rod: allows to see in dimly lit but can't discriminate color
cones: give color & sharper images required in intense light |
optic disc | s: where the optic nerve comes in
why? no retina can attach to the spot |
fovea centralis | site of sharpest vision where we want light to go |
3 chambers & area | place: between
anterior: cornea & iris
posterior: iris & lens
vitreous: behind lens |
aqueous humor | location: anterior cavity
f: provides transportation for nutrient & waste, forms a fluid cushion, helps retain eye shape, stabilizes position of retinal |
vitreous humor | location posterior cavity |
glaucoma | build up of fluid in the eyes because no blood can flow->no O2->effects retina->eventually lose photoreceptors |
lens | held behind the iris by suspensory ligaments
composed of lens fibers surrounded by a capsule
focuses light on the retina
bulges for near vision & no tension
flattens for distant & has tensiion |
cataract | lens becomes clouded & can happen with general age |
eyelids | levator palpebrae superioris & orbiculari oculi
tarsal glands |
conjunctiva | protect doesn't allow things to go back in eye
layers: palpebral (inner of eyelid) & bulbar |
conjunctivitis | pink eye |
lacrimal apparatus | glands: produces tears & enzyme lysozyme & antibodies for antibacterial
lacrimal papilla
punctum
lacrimal canal
lacrimal sac
nasolacrimal duct |
extrinsic muscles | lateral rectus- laterally
medial rectus- medially
superior rectus- up & in
inferior rectus- down & in
superior oblique- down & out
inferior oblique- up & out |
5 processes required for focusing of light waves & stimulation of photoreceptors | 1. light waves in
2. refraction through media
3. accomodation of lens
4. constriction of pupil regulate light into vitreous
5. convergence of eyeballs=acuity |
transmission of light waves | cornea -> aqueous humor -> lens -> vitreous humor |
refraction | bending of light waves occurs when light passes @ an angle of one density to another
light focuses on the retina upside down & reversed L to R brain fixes |
structures in refraction & why | cornea- major bender
fluids very little effect
lens- adjust the shape of your lens to sharpen images by getting them to cross @ fovea ciliary body & smooth muscle adjusters |
lenses | convex- converge light waves
concave- diverge light adjust it |
myopia | "nearsighted" crosses too far away from retina b/c bend too soon could be lens |
hyperopia | "farsighted" light waves don't bend very much & don't cross b4 fovea |
accomodation | automatic adjustment of the curvature of the lens by contraction of the ciliary muscles to focus light waves on retina
occurs when objects are viewed closer than 20 ft |
how lens bulges | ciliary muscles contract & suspensory ligaments are loosened & lens bulges for accomodation |
presbyopia | accomodation disorder lens loses elasticity & near images focus behind retina old age "nearsight" |
constriction of pupil | radial- contract bigger/dilate
circular- contract smaller/constrict
triggered by light intensity & near vision
pathways:
~ parasympathetic of circular
~ sympathetic to radial dilate pupil |
convergence of the eyeballs | eyes rotate medially when viewing close objects with medial rectus
light waves entering each eye will focus on the same part of retina |
amblyopia | lazy eye
deviation of one eye
no concurrent convergence
2 images perceived by visual cortex |
retinal pigaments composed by | Vitamin A:orange & red veggies |
stimulation of photo receptors | photon of light reaches rod pigaments absorbs the light -> retinal & opsin separate from each other -> retinal is converted to original shape with use of ATP -> retinal & opsin comes back together nothing can happen in cell while doing this |
achromatopsia | color blindness missing certain pigments in cones |
nyctalopia | night blindness something wrong with the rods usually caused by prolonged deficiency of vitamin A which can permanently damage |
pathway of vision to brain | photoreceptors -> neurons of retina -> optic nerve -> optic chiasma -> optic tract -> thalmus -> primary visual cortex occipital lobe |
binocular vision & depth perception | field of vision overlaps
when only one eye functions properly depth perception is lost |
blindness | from same eye
so left field = left eye blind |
auricle is composed of | elastic cartilage
skin
helix
lobe
tragus |
external auditory canal | where ceruminous glands are |
tympanic membrane | double layer epithelium that can repair self
sensory innervation by cranial nerves |
middle ear | air-filled chamber=tympanic cavity
seperated from outer by eardrum inner by round & oval windows |
eustachian tube | that adjust pressure to equalize pressure on both sides of tympanic membrane |
ossicles | malleus, incus, & stapes
transmit sound waves from tympanic membrane to oval window |
muscles in ear | tensor tympani attaches to malleus
stapedius attaches to stapes
involved in reflexes to prevent damage to membranes & receptors |
inner ear | acts like bicycle tire
bony labyrinth contains fluid known as perilymph outer tube
membranous labyrinth contains endolymph inner tube
vestibule, semicircular canals, cochlea, organ of corti |
vestibule | bony contains round & oval windows
membranous 1. utricle top & saccule little 2. macula contains hair cells which sense gravity & linear movement & change in position of head |
otoliths | rocks in ear that moves with gravity on top of gel of cilia from macula static |
semicircular canals | membranous- semicircular ducts
ampulla- swellings where ducts connect with utricle
crista ampullaris contains hair cells which sense dynamic rapid turns embedded in flat gel called the capula |
cochlea | chambers: scala vestibuli- upper & continuous with vestibule & scala tympani- lower ends at round window both contain perilymph
cochlear duct - middle with endolymph roof: vestibular membrane & floor: basilar membrane |
organ of corti | in coclear duct along basilar membrane
where mechanical impulses converted to nerve impulse
sensory cells are hair cells 16,000 embeded on tectorial membrane
functional unit of hearing |
otitis media | middle ear infection usually bacterial some viral
tubes put in the membrane to drain fluid |
conduction deafness | conduction pathway usually b.w tympanic membrane to the oval window sometimes even the fluids or b4 the membrane are effected
causes: earwax, infection of middle ear, stuff in ear |
sensory deafness | something wrong with the receptors cells, craniall nerve VIII temporal lobe anything starting at the receptors to where the perception occurs |
tinnitus | "ringing in your ears" irritated cells by over stimulation like driving in car for long time |
smell | location: roof of nasal cavity
receptors: chemoreceptors-smell dissolves & can note smell & stimulated by chemicals dissovled in fluids (breathe in gas_ |
olfactory organs | found in the roof of the nasal cavity
composed of olfactory receptor cells (bipolar neurons with cilia) surrounded by supporting epithelial cells |
olfactory pathway | olfactory receptor cells -> through the holes in the ethmoid bone to the olfactory bulb -> olfactory tracts -> medial temporal lobe |
lesions in olfactory | hallucination usually bad smell |