Lecture 20 - Ear and Eye Flashcards
3 layers of the eye
tunica fibrosa, Uvea, and Retina
components of the tunica fibrosa
sclera and cornea
components of the uvea
choroid (vascular layer that provides nutrients to the retina), ciliary body, and iris
components of the retina
neural (rods and cones) and non-neural (lines the ciliary body and iris)
Anterior chamber vs the posterior chamber
Anterior - in front of the iris
Posterior - behind the iris in the vitreous chamber
Macula (fovea)
only cones in the back of the eyeball region. responsible for visual acuity and central focus.
Where is the blind spot in the eye?
where they are no rods or cones where the optic nerve and blood vessels leave.
What did the lens develop from?
tunica albuginea.
Where are the sclera and cornea located?
Make up the tunica fibrosa (outer most layer). Sclera in the back of the eye and the cornea in the front that is in contact with air and fluid.
Sclera make up and function
CT layer with fibroblasts, fibrous and amorphous tissue. Holds the eye in place
Cornea’s 5 layers
corneal epithelium, bowman’s membrane (non-cellular, thick extracellular material), stroma (thickest), descemet’s membrane, and endothelium (squamous)
Canal of Schlemm location and function
junction of sclera and cornea. facilitates equilibrium of pressure in the eye.
What surrounds the canal of schlemm?
trabecular networks
Choroid
vascular layer. provides nutrients to the sclera and the retina. contains the choriocapillary layer which is closest to the rods and cones of the retina. also contains melanocytes
Ciliary body
containing muscle that can contract the shape of the lens for visual accommodation.
Ciliary processes function
folds of epithelium on the surface of the muscle. Zonula fibers are attached to the lens, allowing for contraction or relaxation of the lens.
Ciliary processes make up
double layer of low columnar to cuboidal. Non-pigment on the outer layer and pigmented on the inner layer.
Iris
double layer of epithelium continues to the posterior iris. eye color is determined by amount of pigment in the epithelium.
Eye color
determined by amount of pigment in the epithelium. Less pigment (blue), intermediate (green), more pigment (brown)
Zonula fibers
oxytalin fibers (elastic fibers) that connect the ciliary proccesses to the lens.
Ora serrata
transition from the neural to non-neural retina
3 layers of photosensitive cells
outer layer - rods and cones embedded in the pigmented epithelium
middle layer - bipolar neurons
inner layer - ganglion cells
Mullet cells
support cells in the neural retina
Rod cells
black to shades of grey and white (rhodopsin)
Cone cells
color (variants of iodopsin)
Dry vs wet macula degeneration
dry - cellular debris between retina and choroid
wet - blood vessels grow from choroid and leak
4 accessory structures of the eye
lens, eyelid and conjunctiva, and lacrimal apparatus
Layers of the lens
Lens capulse (proteoglycans, type IV collagen), Lens epithelium (simple cuboidal to columnar), differentiating lens fibers, and mature lens fibers
Conjuctiva of eyelid
inner most layer and is in contact with the eyeball. Stratified columnar or stratified squamous.
Tarsal fibroelastic plate of the eyelid
provides rigidity, helps in movement
Meibomian gland of eyelid
secretes sebaceous type materials
Orbicular muscle of eyelid
contracts to help you move your eyes
Lacrimal apparatus
produces tears. tubuloalveoli acini and serous
Structures of the outer ear
pinna (lobe), auditory canal and ceruminous glands, and tympanic membrane (ear drum)
Pinna components
elastic cartilage and connective tissue
3 components of the tympanic membrane
external epidermis, middle fibrous CT, and inner simple cuboidal and or squamous epithelium
3 articulating bones
Malleus (hammer), incus (anvil), and stapes (stirrup)
purpose of the middle ear
to amplify the sound and to cause vibration of the oval window of the inner ear
2 nerves connected to the inner ear
vestibular and cochlear nerve
Vestibule
contains the utricle and saccule (which is responsible for motion - and has the macula).
Semicircular canals
in 3 different orientations to help with balance. contain the cristae ampullares (help with orientation and motion)
Cochlear duct
organ of corti (responsible for hearing via sensory hairs)
3 inner ear sensory regions
vestibule, semicircular canals, and cochlear duct
Most important chamber of the cochlear
scala media. endolymph filled (via stria vascularis layer of cells) to help maintain the viability of the organ of corti
How the organ of corti works
fluid within the canal is pushed by a pressure wave and causes the tectorial membrane to rub against the hair cells. This vibration is then transmitted to the cochlear/auditory nerve
Macula components
sensory cells that contain stereocilia and one true long cilia in a gelatinous layer. Otoliths on top of the layer. Movement will cause the gelatin layer to move. This causes an opening of ion channels in the hair cells.
Cristae ampullares
the copula (gelatinous layer) rubs against the other side of the canal.
