anatomy ch.16

tarsal glands

-modified sebaceous glands embedded in the tarsal plate of the eyelid -secrete an oily secretion that lubricates the surface of the eye

anosmia

;absence of the sense of smell-zinc deficincy, coled, excessive mucus, blow to head that tears oflactory nerves

superior tarsal muscle

Attaches to tarsus of upper eyelid Innervated by sympathetic nerves from superior cervical ganglion (Horner's) Elevates eyelid involuntary muslce that prevents the upper eylid from drooping

Cation channels allow cations, especially potassium to move through Potassium high in endolymph; therefore enters cell causing depolarization

Bending toward short stereocilia channels close hyperpolarization

Hair cells = receptor cells = modified neurons Hair cells synapse on afferent axons of CN VIII Axons make up cochlear nerve One hair cell per one cochlear nerve fiber

Cochlear nerve enters brainstem Synapses with second-order neuron

Why is the sense of touch not considered a "special sense"?

Its receptors are widespread throughout the body. Submit

refractory media

Light bending structures: lens, cornea, and humors

hair cells located in ampulla for eq

Located in gelatinous material covered by otoliths

Utricle—detects forward and backward motion

Saccule—detects up and down motion

Conductive deafness Inadequate conduction of sound waves through external and/or middle ear

Sensorineural deafness Inadequate transduction of sound waves to electrical signals in inne

Identify the areas that are filled with aqueous humor.

The anterior and posterior chambers (anterior segment)

lacrimal punctum

The edge of each eyelid has a tiny opening, through which tears drain.

You are listening to music on your iPod at a very loud volume. What happens in your middle ear to protect the hearing receptors in your inner ear?

The tensor tympani and stapedius muscles contract reflexively.

tensor tympani and stapedius

Two muscles in the middle ear that decrease ossicle vibrations when tensed Muffle loud sounds and protect the inner ear

blood supply of retina

Two sources of blood supply Choroid supplies outer third (photoreceptors) Central artery and vein of retina supply inner two-thirds Enter/exit eye in center of optic nerve Vessels visible in living person

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses; ossesous psiral lamina (Bone); cochlear nerve ( part of vetibulochochlear nerve VIII)

cochlear duct

a fluid filled cavity within the cochlea that vibrates when sound waves strike it

Identify the fluid filled space between the cornea and iris.

anterior chamber

anatomy of eyeball

anterior pole, posterior pole, aqueous humor, vitreous humor

ciliary zonule

attaches the lens to the ciliary body

external ear

auricle/pinna-shell-shaped projection external acoustic meatus-sweat glands and sebaceous glands to make ear wax tympanic membrane; eardrum

visual pathway

axons of ganglion cells exit the eye in optic nerve (II) and cross over optic chiasma (decussatate) and continue in an optic tract; go to lateral geniculate nucleus of the thalamus and go to primary visual cortex

In hyperopic (farsighted) eyes, diverging light rays from nearby objects cause the focal point to occur __________, resulting in __________ objects to appear blurry.

behind the retina / nearby

optic disc

blind spot; circular elvation where axons of gaglion cells converge to exit eye as optic nerve; lacks pohotoreceptors

internal ear

bony labyrinth and membranous labyrinth

bony labyrinth

cavity consisting of semicircular canals, vestibule and cochlea

close-up

ciliary muscle contracts, releasing tension on ciliary zonulue, lens becomes rounder and can see closer; controleld by parasympathetic fibers that signal the ciliary muscle to contract

conversion of sound to action potentials

cochlea

tarsal plates

connective tissue within the eyelids

membranous labyrinth

continous series ofmembrane-walled sacs and ducts that fit loosely within bony labyrinth

posterior canal

detects movement of head up and down to the side

frequency

determined by where on the basilar membrane deflection occurs

dim light/distant vision

dialtor pupillae contracts to widen the pupil

inferior oblique muscle

elevates eye and turns it laterally

superior rectus muscle

elevates eye and turns it medially

The pupil can adjust its size independent of the iris.

false

The iris divides the eye into the anterior and posterior segments.

false, the lens does

hyperopia

farsightedness; eye is short, causing focal point to occur behind the retina; need convex lenses

each olfactory sensory neuron has an axon that enters the CT of lamina propria; the axons gather into nerve bundles called

filaments of the olfactory nerve (cranial nerve I); penetrates the cribriform plate of ethmoid bone and enters olfactory bulb where the axons branch profusely and synpase with nursons called mitral cells

anterior segment

filled with aquesous humor; renewed for life

posterior segment

filled with clear vitreous humor; jellylike substance contianing fine firils of colalgen; fn to trnasmit light, support posteiror surface of lens, maintain intraocular pressure; have what you have

perilymph

fluid contained in the labyrinth of the inner ear

endolymph

fluid within the membranous labyrinth of the inner ear high concentration of potassium

ampullary cupula

gelatinous cap overlying hair cells of the crista ampullaris

lacrimal gland

gland located in the upper outer region above the eyeball that secretes tears

taste bud

globular collection of 50-100 epithelial cells gustatory: basal: gustatory hairs project from gustatory epithelial cells and edxtend through taste pore to surface of epithelium

taste info reaches brian stem and cerebral cortex through

gustatory pathway; occurs in facial nerve (VII), glossopharyngeal neve (IX), and vagus nerve (X); synapses in nuclues in medulla called solitary nuclues; impulses then goes to thalamus, and gustatory area of cerebral cortex in insula lobe

presyopia

hardening of lens as it gets thicker and less ealastic; convex corrective lenses correct (reading glasses)

mechanoreceptor

hearing, eq

choroid

highly vascular; melanocytes pigment it preventing light from scattering within eye; between sclera and retina; corresponds to arachnoid and pia mater in brain

chalazion

infection of a tarsal gland

sty

infection of ciliary gland

Which of these extrinsic eye muscles depresses the eye and turns it medially?

inferior rectus

Identify the structure that regulates the amount of light entering the posterior segment of the eye.

iris

Odors may elicits a variety of emotions if these impulses are relayed through the __________.

limbic system

superior oblique msucle

loops through trochlea, turns eye down and out

rod cells

more numerous; more sensite to light; permit vision in dim light; provide neither sharp images nor color viion, things look gray and fuzzy in dim light

first level of amplification

movement of ossicles

medial rectus muscle

moves eye medially

second level of amplification

mvt of oval window

myopia

nearsightedness; shape of eye/bending of lens results in focal point for distant objects that is in front of the retina; lens too strong for size of eye; need convex concave corrective lenses to diverge light

pupillary light reflex

normal constriction of pupils when bright light shines on retina

ucinate fits

olfactory hallucinations

sclear

opaque white, tough; white of the eye; protescts eyeball and provides shape; corresponds to dura mater of brain

cone cells

operate best in bright light; enable high-acuity, color vision; blue, red, green light substypes

anular ring

origin of the four rectus muscles

retina

outer pigemented layer lies agaisnt choroid and fn to absorb light and prevent it from scattering the eye; the thicker inner neural layer is nervous tissue that contaisn light-sesitive photoreceptor cells

The equilibrium pathway transmits most of its information to lower brain centers because the __________.

pathway responds to loss of balance and must be rapid and reflexive to prevent injury

process of eye

photoreceptor cells signal the bipolar cells which signal the ganglion cells to generate nerve impulses potentials, the axons from ganglion cells converge to form optic nerve

conjunctivitis

pink eye;inflammation of the conjunctiva

lacrimal apparatus

produces, distributes, and removes tears

olfactory epithleium

pseudostratified columnar with millions of biopolar nueorns called olfactory sesnory neurons which are surrouned yby supporting epihelial cells; there are olfactory stem cells that continually form new olfactory sensory neurons

special sesnory receptors are localized and confined to head region

receptor cells; neuronlike peithelial cells or peripheral neurons that transfer sensory info

see far

resting eye; lens stretched and set to focus almost-aprallel rays from distant points

inner layer

retina and optic nerve

fibrous layer

sclear and cornea

lateral canal

side to side

levator palpebrae superioris

skeletal elevates upper eyelid

lacrimal canliculus

small tube that tears epty into where tehy tracvel to lacrimal sac; this flue then enters nasolacrimal duct which empties into nasal cavity at inferior nasal meatus

bright light/close vision

sphincter pupillae contracts to constrict the pupil

The scala tympani __________.

terminates at the round window at the base of the cochlea and is filled with perilymph

middle ear

the chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window

When the lens of the eye bulges for close vision, which of the following happens?

the ciliary muscles contract

accommodation

the process by which the eye's lens changes shape to focus near or far objects on the retina

cornea

the transparent layer forming the front of the eye; avascualr; receives oxygen from air in front of it and oxygen/nutrients from aqeuous humor

conjunctiva

the transparent mucous membrane that lines the underside of each eyelid and continues to form a protective covering over the exposed surface of the eyeball palpebral conjunctiva-covers inner surfaces of eyelids bulbar conjunctiva folds back over anterior surface of eye, covers white of eye

ciliary body

thickened ring of tissue that encircles the lens; ciliary muscles acts to fucus lens; ciliary processes are raidating folds

fovea centralis

tiny pit or depression in the retina that is the region of clearest vision; contains only cones

auditory ossicles

transmit and amplify vibrations from tympanic membrane to oval window: malleus, incus, stapes (goes into oval window)

inferior rectus muscle

turns eye inferiorly and medially

lateral rectus muslce

turns eye laterally

Olfactory sensory neurons __________.

undergo replacement throughout life

anterior canal

up or down

cranial nerve 8

vestibular-eq cochlear-hearing

Receptor cells for sound Stereocilia Tips embedded in tectorial membrane

vibrations in perilymph of scala vestibuli cause deflection (vibration) of organ of corti This causes bending of haircell steriocilia

iris

visible, colores part of eye between cornea and lens; base attaches to ciliary body; round central opening (pupil) allows light to enter the eye; sphincter and dilator pupillae muscles