Exercise 24: Special Senses
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poorlilrich on February 13, 2010
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98 terms
Terms | Definitions |
|---|---|
 Palpabrae | eyelids |
| Conjunctiva | the thin, protective mucous membrane that covers the anterior eye and folds to cover the inner eyelid |
| Palpebral conjunctiva | covers the interior of the eyelid |
| Bulbar conjunctival | covers the anterior part of the white of the eye, but not the cornea |
| Lacrimal apparatus | is a group of structures involved in producing and draining tears |
| Lacrimal gland | produces and secreates tears onto the eye surface |
| Lacrimal canals | drain tears from teh eyes into the enlarged lacrimal sac |
| Lacrimal sac | the lacrimal canals drain tears from the eyes into this sac |
| Nasolacrimal duct | receives tears from the lacrimal sac and drains the tears into the nasal cavity |
| Extrinsic eye muscles | aare six skeletal muscles that insert on teh exterior of the eyeball to move the eyeball in all directions: the superior, inferior, medial, and lateral rectus muscles are parallel to the long axis of the eyeball; the superior and inferior oblique muscles attach to the eye ball at an angle |
| Inferior oblique | moves eye superiorly and laterally |
| Inferior rectus | moves eye inferiorly |
| Lateral rectus | moves eye laterally |
| Medial rectus | moves eye medially |
| Superior oblique | moves eye inferiorly and laterally |
| Superior rectus | moves eye superiorly |
| Wall of the eyeball | has three layers: the outer fibrous tunic, the middle vascular tunic, and the inner retina |
| Fibrous tunic | is composed of teh cornea and sclera |
| Cornea | the transparent anterior portion that covers the iris and pupil |
| Sclera | the touch, white part of the eye that forms the majority of the eyeball |
| Scleral venous sinus | is an opening found at the junctino of the cornea and sclera; drains aqueous humor back into the bloodstream |
| Vascular tunic | is composed of the iris, ciliary body, and choroid |
| Iris | the most anterior portion of the vascular tunic and contains pigmented cells; it is made of circular smoth muscle and controls the pupil size |
| Pupil | is the opening in teh middle of the iris that allows light to enter the eyeball and changes size in response to teh intensity of light |
| Ciliary body | begins posterior to teh iris at the junction of the cornea and sclera and consists of the ciliary muscle and ciliary processes |
| Ciliary muscle | is a circular smooth muscel that ocntracts to control the sape of the lens |
| Ciliary processes | are folds that protrude from teh ciliary body toward the lens; they contain capillaries that secrete aqueous humor, the fluid in the anterior chamber of the eyeball |
| Suspensory ligaments | are thin fibers that attach the lens to the ciliary processes |
| Choroid | is the most posterior part of the vascular tunic that lines most of the interior of the sclera; it contains many blood vessels that nourish teh retina |
| Retina | is the inner coat that begins at teh ora serrata; the retina continues posteriorly, lining the interior of the choroid; teh pigmented layer of the retina is the outer portion, and the neural layer is the inner portion that contains photoreceptors and associated neurons |
| Ora serrata | the serrated boundary between the ciliary muscle and the retina |
| Interior of the eyeball | contains the lens, anterior cavity, and vitreous chamber |
| Lens | divides the interior of the eyeball into an anterior cavity and a vitreous chamber (posterior cavity) |
| Anterior cavity | is a space between teh cornea and the lens that is filled with watery aqueous humor; this cavity is subdivided into an anterior chamber and a posterior chamber |
| Anterior chamber | part of the anterior cavity; between the cornea and the iris |
| Posterior chamber | part of the anterior cavity; betwen teh iris and the lens |
| Vitreous chamber | is the larger, posterior cavity located between teh lens and the retina; is filled with a gel-like substance called teh vitreous body (humor) that holds the retina flat agains the choroid |
| Neural portion of the retina | an outgrowth of the brain and contains three layers of neurons: the photoreceptor layer (deepest cell layer), the bipolar cell layer (middle layer), and the ganglion cell layer (the superficial cell layer) |
| Photoreceptor cell layer | contains the rods and cones, which synapse with the bipolar neurons in teh bipolar cell layer |
| Rods | are used in night vision and respond to low levels of light, allowing us to perceive shades of gray, black, and white; visual acuity with rods is low |
| Cones | require brighter light for stimulation, but allow us to see color and provide high visual acuity |
| Bipolar cell layer | cells here synapse on the ganglion cells in teh ganglion cell layer |
| Ganglion cell layer | axions from the ganglion cells extend through the optic disc and leave the eyeball as the optic nerve |
| Optic disc | does not contain photoreceptors and forms the blind spot of the retina; it is also teh site where the central retinal artery and vein center enter and leave the retina, and the only place where the retina is secured to teh otehr layers of the eyeball |
| Macula lutea | the site of macular degeneration, is in the center of the neural portion of the retina |
| Central fovea | in the middle of the macula lutea is this; this area of the retina has the highest density of cones of any area of the retina and is not covered by ganglion and bipolar cell layers; therefore , this area ahs the highest visual acuity of any area of the retina; when we look at an object, the light rays reflected from teh object are focused onto teh central fovea |
| Ophtalmoscope | the retina can be viewed with this; it illuminates teh interior of the eye |
| Regions of the ear | the external ear, the middle ear, the internal ear |
| External ear | consists of the auricle, external auditory canal, and tympanic membrane; extends fromt eh auricle to teh tympanic membrane |
| Auricle | teh flexible external structure that is commonly called the ear, collects sound waves and directs them toward the external auditory canal |
| Helix | the rim of the auricle |
| Lobule | the flesy, inferior portion of the auricle |
| External auditory canal | conducts sound waves from the auricle to the tympanic membrane |
| Tympanic membrane | (eardrum) converts sound waves to vibrations that are transferred to middle ear structures |
| Middle ear | is an air-filled cavity within the temporal bone that extends from teh tympanic membrane to teh oval window; structures include the auditory ossicles, oval window, roudn windown and auditory tube |
| Auditory ossicles | are small bones within teh cavity that are connected by synovial joints; they transfer vibrations from the tympanic membrane to teh oval window; include the malleus, incus, and stapes |
| Malleus | the outermost auditory ossicle and is attached to the tympanic membrane |
| Incus | the middle auditory ossicle and connects to the stapes |
| Stapes | the innermost auditory ossicle; connects to the incus and teh oval window |
| Oval window | the membrane-covered opening that separates teh mdidle and inner ear and transfers vibrations to the inner ear |
| Round window | is a membrane-covered opening between teh middle ear and cohlea |
| Auditory tube | conects the middle ear to the nasopharynx, and equalizes the air pressure of the ear with atmospheric air |
| Internal ear | is housed within the temporal bone; it consists of cavities within teh bone called the bony labyrinth that encloses a series of connected membranous sacs, the membranous labyrinth |
| Bony labyrinth | contains a fluid called perilymph that surrounds the membranous labyrinth; endolymph is the fluid within teh membranous labyrinth; the bony labyrinth has 3 main regions: the vestibule, the semicircular canals, and the cochlea |
| Vestibule | is the middle area of the bony labyrinth that encircles 2 sections of membranous labyrinth, the utricle and the saccule |
| Utricle | is the posterior section of the membranous labyrinth within the vesttibule, and is houses equilibrium receptors |
| Saccule | is the anterior section of the membranous labyrinth within the vestibule; the saccule is continuous with the utircle and also houses equilibrium receptors |
| Semicircular canals | are 3 bony canals posterior to the vestibule that project posteriorly, laterally, and superiorly from teh vestibule; each canal is at right angles to the other two |
| Semicircular ducts | are sections of membranous labyrinth within the semicircular canals which contain equilibrium receptors and connects with the utricle |
| Ampulla | is the widened end of each semicircular canal and duct |
| Cochlea | the spiral area of teh bony labyrinth anterior to the vestibule; makes 3 turns around a bony cone; a section through this shows 3 channels: the scala vestibuli, teh cochlear duct, and teh scala tympani |
| Cochlear duct | is teh section of membranous labyrinth within the cochlea; contains the hearing receptors and is connected to teh saccule |
| Vestibulocochlear nerve | hearing and equilibruim receptors initiate nerve impulses which are carried by this nerve to the brain; has 2 branches: the vestibular branch and the cochlear branch |
| Vestibular branch | part of the vestibulocochlear nerve; carries nerve nerve impulses generated by equilibrium receptors |
| Cochlear branch | carries nerve impulses generated by the hearing receptors |
| Scala vestibuli | is part of the cochlea and is superior to teh cochlear duct; it is separated frmo the cochlear duct by the vestibular membrane; it is continuous with the scala tympani and is filled with perilymph |
| Scala tympani | is also part of the cochlea and is posterior to cochlear duct; it is separated from teh cochlear duct by the basilar membrane; it is continuous with the scala vestibuli and is filled with perilympth |
| Cochlear duct | is part of the membranous labyrinth, houses the spiral organ of corti and is filled with endolymph |
| Spiral organ of Corti | sits on teh basilar membrane; it contains hair cells (receptors for hearing) and supporting cells |
| Hair cells | have a hair bundle composed of stereocillia at their apical end; superior and in contact with teh stereocilia is the tectorial membrane; the basal end of teh hair cells synapse with sensory and motor neurons from the cochlear branch of the vestibulocochlear nerve |
| Types of equilibrium receptors | there are 2 types: the maculae and the cristae |
| Maculae | located in teh utricle and saccule; provide information on head position (static equilibrium), as well as linear acceleration and deceleration, a type of dynamic equilibrium; consists of hair cells with hair bundles and supporting cells |
| Otolithic membrane | is in contact with teh hair bundles of the maculae; contains calcium carbonate crystals called otoliths |
| Otoliths | movemtn of the head causes movemetn of the otoliths and otolithic membrane, which bends the hair bundles; the dirrection of movement will determine if the hair cells release more or less neurotransmitter to the associated sensory neurons |
| Crista | located in teh membranous semicircular ducts within the ampullae; detects rotational accelaeration and deceleration, a type of dynamic equilibrium; each consists of hari cells and supporting cells; the hair bundles of the hair cells are covered by a gelatinous structure called the cupula |
| Cupula | a gelatinous structure that covers the hair bundles of the hair cells in teh crista; when the head moves, movement of the endolympth pushes the cupula causing the hair cells to bend; bending of the hair bundles results in generation of nerve impulses in the vestibular branch of the vestibulocochlear nerve |
| Olfactory epithelium | covers teh inferior surface of the cribriform plate, the superior nasal concha, and the upper part of the middle nasal concha; contains olfactory receptors cells, basal stem cells, and ducts of olfactory glands |
| Olfactory receptor cells | are bipolar neurons whose dentritic end is embedded in the mucus layer covering the surface of the olfactory epithelium and whose axons form the olfactory nerves; they are located on olfactory haris that project from the dentrites of the olfactory receptor cells |
| Olfactory nerves | pass through the olfactory foramina in the cribriform plate and synapse on neurons in the olfactory bulb; nerve impulses then travel along the olfactory tract to the lateral olfactory area of teh cerebral cortex; olfactory receptors adapt to odors very quickly |
| Taste buds | are found on the tongue, soft palate, pharynx (throat) and larynx; are microscopic, onion shaped structures that contain gustatory cells, gustatory hairs, and supporting cells |
| Gustatory cell | each has one gustatory hair that projects through an opening, the taste pore, on the apical end of the taste bud |
| Gustatory receptors | are located on the gustatory hairs; the basal end of gustatory cells synapse onto the dendritic end of sensory neurons; axons from the sensory neurons contribute fibers to the facial nerve (cranial nerve VII), glossopharyngeal nerve (IX), or vagus nerve (X), depending on the location of the taste bud |
| Papillae | taste buds on teh tongue are located here; elevated structures that give the tongue its rough appearance; there are 4 types: vallate, fungiform, foliate, and filiform |
| Vallate papillae | are the largest papillae and form an inverted V at the posterior of the tongue |
| Fungiform papillae | are mushroom shaped and are scattered over the surface of the tongue |
| Filiform papillae | are slender, pointed, projections that cover teh surface of the tongue and give the tongue a rough texture; these papillae have tactile receptors but not taste buds; taste buds are found in vallate, fungiform, and foliate papillae |
| Foliate papillae | are present mostly in children and are lcoated in lateral margins of the tongue |
| Taste sensations | there are four primary: sweet, bitter, salty, and sour; and a possible fifth, MSG (monosodium glutamate); gustatory receptors most senstive to sweet and salty sensations are found on the tip of the tongue, while bitter sensation are in teh back and sour sensations are on teh sides of the tongue; other taste sensations are a mixture of these four; smell, temperature, and texture (tactile sensation) contribute to our sense of taste |
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