A&P Lab 12: Special Senses Flashcards
Eyebrows
fringe of hair superior to each orbit, which acts as a partial filter
Palpebrae
the eyelids, each composed of an outer layer of skin and an inner layer of mucous membrane
Eyelashes
the small hairs attached to the distal end of each eyelid, which help filter particles and sunlight
Conjunctiva
a thin, protective mucous membrane that covers the externally exposed surfaces
Palpebral conjunctiva
covers the inner wall of the eyelid
Bulbar conjunctiva
covers the anterior eye surface
Lacrimal apparatus
the structures that produce and drain the tears
Lacrimal gland
lateral and superior to each eye; produces tears that flow along the eye surface
Lacrimal canals
2; extend medially to drain tears into the lacrimal sac
Lacrimal sac
collecting chamber for tears
Nasolacrimal duct
channels tears from the lacrimal sac into the nasal cavity
Extrinsic eye muscles
6 skeletal muscles that are exterior to the eye and insert onto its outer surface to provide eye movement
Superior, inferior, medial, and lateral rectus
muscles which extend in a direction parallel to the long axis of the eyeball
Superior and inferior oblique muscles
muscles which extend at an angle to the long axis of the eyeball
Fibrous tunic
the outer layer of the eyeball; a tough, protective covering that consists of 2 components, the cornea and sclera
Cornea
the transparent anterior portion covering the iris and pupil
Sclera
the white external covering of the eye, which is composed of collagenous fibers; includes an opening called the scleral venous sinus at the junction of the cornea and itself
Scleral venous sinus
canal of Schlemm; opening in the sclera
Vascular tunic
middle layer of the eyeball, which transmits blood vessels to various parts of the eye; consists of the iris, ciliary body, and choroid
Iris
“rainbow”; colored circle of the eye, forming the anterior part of the vascular tunic; composed of circular smooth muscle that controls the diameter of the pupil
Pupil
black opening in the center of the iris; regulates the amount of light entering the eye (iris controls its diameter)
Ciliary body
structure arising at the junction of the cornea and sclera; consists of the ciliary muscle and ciliary processes
Ciliary muscle
circular arrangement of smooth muscle that alters the shape of the attached lens; part of the ciliary body
Ciliary processes
folds of tissue extending from the ciliary body toward the lens; contain fibrous extensions called suspensory ligaments
Suspensory ligaments
the ciliary processes contain these fibrous extensions, which form attachments to the lens
Ora serrata
at the posterior fringes of the ciliary muscle is this serrated feature
Choroid
the posterior part of the vascular tunic; lines the interior of the sclera and includes pigments that absorb light; highly vascular
Retina
the inner layer of the posterior eyeball, which contains the sensory receptors sensitive to light; begins at its union with the ora serrata to cover the innermost posterior wall, deep to the choroid; includes an outer pigmented layer and an inner portion of sensory receptors and neurons (neural layer); also includes photoreceptors, bipolar cell layer, ganglion cell layer, macula lutea, and the optic disc
Pigmented layer
outer portion of the retina
Neural layer
inner portion of the retina with sensory receptors and neurons
Photoreceptors
sensory receptors of the eye, which respond to light by triggering action potentials
Rod cells
respond to low levels of light to allow us to perceive shades of gray, black, and white
Cone cells
require brighter light; enable us to see color
Bipolar cell layer
neurons that form a thin layer superficial to the photoreceptors; its neurons synapse with rods and cones
Ganglion cell layer
the neurons that form a layer superficial to the bipolar cells and synapse with them; its axons extend through the optic disc to exit the eyeball as the optic nerve
Optic nerve
CN II; creates a blind spot where it exits the eyeball
Macula lutea
region of the retina that contains only cone cells; the area in its center contains the highest concentration
Fovea centralis
highest concentration of cone cells at the center of the macula lutea; area of highest visual acuity (sharpness of vision)
Optic disc
the area of the retina that marks the exit of the optic nerve; lacks photoreceptors (forms blind spot)
Blind spot
part of the optic disc that lacks photoreceptors
Interior cavities
interior of the eye, divided into the anterior and posterior cavities
Lens
separates the anterior and posterior cavities; a transparent disc that is thickest in its center; serves to bend light waves before they fall on the retina
Anterior chamber
part of the anterior cavity; located between the cornea and the iris
Posterior chamber
part of the anterior cavity; located between the iris and the lens
Aqueous humor
fluid that fills the anterior and posterior chambers; continually recycled
Vitreous humor (vitreous body)
gelatinous material contained within the posterior cavity; helps stabilize the shape of the eyeball and hold the retina in place
Refraction
the bending of light rays
Accommodates
changing shape (to bend light rays); achieved by contraction or relaxation of the ciliary muscles (pull or relax the suspensory ligaments to flatten or bulge the lens)
Emmetropic
eyesight with a normal range of distance and near vision
Hyperopic
farsighted; eyesight in which the lens fails to accommodate for far vision (distant objects appear blurred)
Myopic
nearsighted; eyesight that fails to accommodate for near vision
Astigmatism
common condition in which the lens is unable to accommodate because the path of light is defective, resulting in blurred near and far vision; caused by irregularities in the curvature of the lens and/or cornea
Presbyopia
condition in which aging causes the lens to lose its elasticity
Distance visual acuity
ability to read at 20 feet; testing for this requires the use of a Snellen eye chart (consists of letters of various sizes on a white background); the distance at which the emmetropic eye can read a line of letters of a particular size is printed at the end of that line
Near visual acuity
ability to read 12-14 inches away; uses the Snellen eye card
Outer ear
collects and funnels sound waves, which are converted to mechanical vibrations by the eardrum
Middle ear
air-filled cavity within the temporal bone that transmits vibrations from the eardrum to the oval window
Tympanic cavity
air-filled cavity of the middle ear
Inner ear
consists of a labyrinth embedded within the temporal bone containing the mechanoreceptors that trigger both hearing and equilibrium
Auricle
external appendage of the ear composed of elastic connective tissue and covered with skin; collection device for channeling vibrations into the ear; AKA the pinna
Helix
outer rim of the auricle
Lobule
feature inferior to the opening in the ear
External auditory canal
opening that penetrates through the mastoid area of the temporal bone and lined with skin; about 2.5cm long and 0.6cm wide; contains ceruminous glands
Ceruminous glands
wax-secreting glands
Tympanic membrane
eardrum; thin membrane of skin that separates the outer ear and middle ear; converts sound waves to mechanical vibrations
Auditory ossicles
3 small bones within the tympanic cavity that articulate to form a tiny lever system, which serve to transmit and amplify the vibrations; malleus, incus, stapes
Auditory tube
AKA Eustachian or pharyngotympanic tube; a narrow tube connecting the tympanic cavity and the nasal cavity; usually closed, but opens during yawning and swallowing to equalize pressure between the middle ear and the external air
Oval window
small membrane-covered opening that separates the middle ear and the inner ear
Round window
small membrane-covered opening between the middle ear and the cochlea (inner ear)
Bony labyrinth
series of internal canals lined with bone within the temporal bone; contains a fluid called perilymph
Perilymph
fluid contained within the bony labyrinth
Membranous labyrinth
a membrane-lined canal that is enclosed within the bony labyrinth; contains a fluid called endolymph
Endolymph
fluid contained within the membranous labyrinth
Semicircular canals
3 large loops (semicircles) that form the posterior aspect of the inner ear; the loops are anterior, lateral, and posterior, each at right angles to the other 2; the interior = membranous labyrinth with perilymph
Ampulla
expanded end of each loop of the semicircular canals; contain sensory receptors involved with equilibrium
Hair cells
sensory receptors involved with equilibrium; located within cristae (ampullares)
Cristae
each of these consists of hair cells and supporting cells
Cupula
the hair cells are covered by this gelatinous structure; when the head moves, movement of the endolymph pushes this against the hair cells, stimulating them to generate action potentials
Vestibule
the middle of the 3 inner ear chambers; includes 2 sacs of membranous labyrinth
Utricle
posterior chamber of the vestibule
Saccule
anterior chamber of the vestibule
Maculae
the utricle and saccule contain these, which house the sensory receptors (hair cells bundled to contact a membrane = otolithic membrane) that respond to head position and gravity to help you to distinguish up from down and changes in speed
Otolithic membrane
houses mineral crystals
Otoliths
mineral crystals housed in the otolithic membrane; movement of the head causes these to shift, bending the hair cells, and stimulating action potentials
Cochlea
the anterior chamber of the inner ear; resembles a spiral snail shell
Cochlear duct
the interior of the cochlea contains membranous labyrinth that encloses this chamber, which is connected to the saccule and houses sensory receptors (hair cells within the organ of Corti) for hearing
Scala vestibuli
superior channel of the inside of the cochlea; contains perilymph
Cochlear duct
middle channel of the inside of the cochlea; filled with endolymph
Vestibular membrane
this thin membrane separates the scala vestibuli from the cochlear duct
Basilar membrane
the opposite membrane of the cochlear duct; border the inferior channel
Scala tympani
inferior channel of the inside of the cochlea; contains perilymph
Organ of Corti
within the cochlear duct, this lies on top of the basilar membrane
Tectorial membrane
in contact with the stereocilia (cilia longer than normal); the basal end of the hair cells synapse with neurons from the cochlear branch of the vestibulocochlear nerve (CN VIII)
Conduction deafness
a loss of hearing may result from this failure to conduct sound waves and vibrations to the inner ear
Sensorineural deafness
a neurological failure such as damage to the vestibulocochlear nerve (CN VIII)
Weber test
examines the ability of a subject to conduct sound waves
Rinne test
examines the possibility of both conduction deafness and sensorineural deafness
Olfaction
sense of smell
Olfactory epithelium
area of sensitivity; includes olfactory cells and supporting cells
Olfactory cells
bipolar neurons whose dendrites are embedded in the nasal mucosa (olfactory hairs)
Olfactory hairs
serves as the actual receptors for dissolved chemicals and are thereby classified as chemoreceptors
Olfactory nerves
the axons of the olfactory cells form these
Olfactory bulb
the axons of the olfactory cells form the olfactory nerves; they extend through foramina in the cribiform plate to enter the cranial cavity, where they synapse with neurons here
Olfactory tract
action potentials travel along this to the olfactory sensory area in the temporal lobe of the cerebral cortex
Gustation
the sense of taste; detected by sensory receptors that form part of the organs known as taste buds
Taste buds
organs of gustation, located mainly on the posterior surface of the tongue; some are found on the soft palate, the pharynx, and the cheeks; each one is a microscopic structure shaped like an onion; chemoreceptors are embedded within them
Papillae
on the tongue, the taste buds are housed within these small projections; 3 types - filiform, fungiform, and large circumvallate
Gustatory cells
chemoreceptors embedded within taste buds
Gustatory hair
the dendrite of a gustatory cell
Taste pore
the gustatory hair projects out of the taste bud by way of this opening
