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72 Cards in this Set
- Front
- Back
General senses
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large group of touch receptors
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Special senses
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taste, smell, sight, hearing, balance
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Special sensory receptors
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localized to head, not free endings of sensory neurons, special receptor cells = neuron-like epithelial cells or small peripheral neurons
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Taste
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gustation, chemoreceptors that respond to food dissolved in saliva fluids, tongue is stratified squamous epithelium
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Filiform papillae
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very numerous, small conical pointed in shape, line up in parallel rows which enables tongue to grasp food, NO taste buds
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Fungiform papillae
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mushroom shaped, spread over anterior 2/3rds of tongue, contain taste buds
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Vallate papillae
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V-shaped row bordering posterior third of tongue, anterior to terminal sulcus groove, contain taste buds
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Taste buds
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contain taste receptors, 50-100 epithelial cells, gustatory and basal cells, long microvilli (gustatory hairs) extend through taste pore to surface, cells replaced every 7-10 days
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Tastes
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sweet, sour, salty, bitter, umami (glutamate)
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Gustatory pathway
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through facial (7), glossopharyngeal (9), and vagus (10) nerves, bitter taste receptors found in stomach, neurons synapse in solitary nucleus of medulla, to thalamus and to gustatory area of cerebral cortex in insula
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Smell
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olfaction, chemoreceptors respond to airborne chemicals that dissolve in nasal mucosa, part of olfactory epithelium (pseudostratified simple columnar), 3 cell types: olfactory sensory neurons, supporting olfactory, basal epithelial cells
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Olfactory epithelium
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contain cell bodies of olfactory sensory neurons, have apical dendrite that projects to epithelial surface and ends in knob with olfactory cilia (receptive structures for smell), mucus captures/dissolves odor molecules
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Smell, body to brain
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gather into bundles of axon filaments of olfactory nerve, pass through cribiform plate of ethmoid bone, attach to olfactory bulbs and synapse with mitral cells, which transmit impulses along olfactory tract to limbic system or piriform lobe
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Anosmia
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absense of sense of smell due to injury, colds, allergies, etc
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Uncinate fits
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distortion of smells or olfactory hallucination, result from irritation of pathways, or after brain surgery or head trauma
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Eye and vision
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contain 70% of all sensory receptors in body, take up 40% cerebral cortex processing info, anterior 1/6th of eye is visible, lens anc iliary zonules divide eye into anterior/posterior segments
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Eyelids (palpebrae)
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separated by palpebral fissure, meet at medial/lateral angles, lacrimal caruncle = reddish elevation at medial canthus, tarsal plates = CT in eyelids, tarsal glands = modified sebaceous glands
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Conjunctiva
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transparent mucous membrane, palpebral conjunctiva, bulbar conjunctiva, conjunctival sac
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Lacrimal apparatus
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keeps surface of eye moist, lacrimal gland produces lacrimal fluid, lacrimal punctum, lacrimal canaliculus, lacrimal sac (fluid empties into nasal cavity), nasolacrimal duct, inferior meatus
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Extrinsic eye muscles
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control eye movement, originate in walls of orbit, insert on outer surface of eyeball, annular ring = origin of 4 rectus muscles (lateral/medial/superior/inferior rectus, superior/inferior oblique)
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Vitreous humor
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clear, jelly-like, transmits light, supports posterior surface of lens, helps maintain intraocular pressure
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Anterior eye chamber
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b/w cornea and iris
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Posterior eye chamber
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b/w iris and lens
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Aqueous humor
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formed from filtrate of capillaries in ciliary processes, flows from posterior chamber through pupil into anterior chamber, reabsorbed into venous blood by scleral venous sinus, renewed continuously, provides nutrients to lens and cornea
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Glaucoma
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intraocular pressure in anterior segment, occurs when aqueous humor drains more slowly than it forms, compression on retina and optic nerve, can lead to blindness
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Lens
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thick, transparent, biconvex disc, held in place by ciliary zonule, lens epithelium = covers anterior surface of lens, elongated lens fibers form bulk of lens, new lens fibers continuously added, lens enlarges throughout life
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Fibrous layer of eye
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external, dense CT in 2 different regions, sclera (white, provides shape and anchor for eye muscles) and cornea, limbus = junction b/w sclera and cornea, scleral venous sinus = allows aqueous humor to drain
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Cornea
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epithelium, thick layer of dense collagen-rich CT, avascular, gets oxygen from air and nutrients from aqueous humor, richly supplied with sensory nerve endings, mostly pain receptors
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Vascular layer of eye
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middle layer, composed of choroid, ciliary body, iris
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Choroid
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vascular, darkly pigmented membrane, under sclera, brown from melanocytes, prevents scattering of light rays in eye, corresponds to arachnoid and pia maters
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Ciliary body
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thickening ring of tissue that encircles lens, smooth muscle which focuses lens
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Ciliary process
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posterior surface of ciliary body
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Ciliary zonule
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suspensory ligament, halo of fine fibrils attached around entire circumference of lens
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Iris
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color of eye, attached to ciliary body and positioned anterior to ciliary body, smooth muscle, pupil = round opening, sphincter and dilatory pupillae muscles, vary size of pupil, papillary light reflex = protective response of pupil constriction when bright light is flashed
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Inner layer of eye
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retina = thin outer pigmented layer with melanocytes and thick inner neural layer with nervous tissue (ends at posterior margin of ciliary body, ora serrata retinae), optic nerve
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Macula lutea
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contains mostly cones
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Fovea centralis
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contains only cones and is region of highest visual acuity
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Optic disc
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blind spot
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Neural layer
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contains photoreceptor cells (rods and cones, signal bipolar cells), bipolar cells (signal ganglion cells to generate nerve impulse), ganglion cells (run along internal surface of retina), 4th type if interneurons (amacrine and horizontal cells) which process visual info, all converge to forms optic nerve
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Rod cells
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more sensitive to light, allow vision in dim light
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Cone cells
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operate best in bright light, enable high-acuity, color vision
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Photoreceptors
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rods/cones have inner and outer segment, outer segments are receptor regions that contain light absorbing pigments, light particles modify the visual pigment, generate nerve impulse
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Visual pathways to cerebral cortex
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begins at retina, light activates photoreceptors, signal bipolar cells, signal ganglion cells, axons exit eye as optic nerve, run through optic chiasm into optic tract, send axons to lateral geniculate nucleus of thalamus and synapse with thalamic neurons, fibers of optic radiation reach primary visual cortex
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Visual pathways to other parts of brain
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some axons from optic tracts brach to midbrain (superior colliculi controls extrinsic eye muscles, pretectal nuclei mediate papillary eye reflexes), others branch to suprachiasmatic nucleus to hypothalamus which processes visual input to help synchronize daily biorhythms with daylight-darkness cycle
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Blood supply to retina
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outer third gets it by capillaries in choroid, inner two-thirds serviced by central artery and vein of retina
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Cataracts
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lens becomes opaque, results in blindness
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Age-related macular degeneration
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involves buildup of deposits in retina, causes loss of vision in macula, which is center of visual field
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Trachoma
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contagious infection from Chlamydia of conjunctiva, causes eyelids to become distorted and inverted, results in eyelashes scraping against cornea which can lead to blindness from corneal scarring
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The ear
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receptor organ for hearing and equilibrium, outer/middle/internal ear
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Outer ear
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auricle (pinna) helps direct sounds, external acoustic meatus lined with skin/hair/sebaceous glands and ceruminous glands, tympanic membrane forms boundary b/w external and middle ears
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Otitis externa
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infection/inflammation of skin lining external acoustic meatus (external ear canal), swimmer’s ear can cause this
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Otitis media
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infection of tympanic membrane
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Middle ear
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tympanic cavity = air-filled space within petrous portion of temporal bone, medial wall penetrated by oval and round window, pharyngotympanic tube links middle ear and pharynx, tensor tympani and stapedius muscles = 2 tiny skeletal muscles in middle ear cavity
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Ear ossicles
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in middle ear: malleus (attached to eardrum), incus (b/w malleus and stapes), stapes (vibrates against oval window)
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Internal ear
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labyrinth, lies within petrous portion of temporal bone
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Bony labyrinth
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semicircular canals, vestibule, cochlea, filled with perilymph ( continuous with cerebrospinal fluid)
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Membranous layrinth
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series of membrane-walled sacs/ducts, fit within bony labyrinth, semicircular ducts, utricle and saccule, cochlear duct, filled with endolymph
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Semicircular canals/ducts
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facilitate equilibrium related to rotational acceleration of head
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Vestibule
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contains utricle (continuous with semicircular ducts) and saccule (continuous with cochlear duct), which contain macula (spot of sensory epithelium), facilitates equilibrium related to static equilibrium and linear acceleration of head
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Macula
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contains receptor cells (hair cells, base synapses with vestibular nerve), monitor position of head when head is still (static equilibrium) and when head is moving straight ahead (linear acceleration), contains columnar supporting cells, apex of stereocilia and one kinocilium, tips of hair cells embedded in otolithic membrane (jelly-like disc that contains crystal of calcium carbonate called otoliths)
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Cochlea
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contains cochlear duct, facilitates hearing, spiraling chamber, coils around a pillar of bone (modiolus), osseous spiral lamina = spiral of bone in modiolus, cochlear nerve runs through core of modiolus, vestibular membrane = roof of cochlear duct, basilar membrane = floor of cochlear duct (supports spiral organ of Corti)
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Cochlear duct
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lies between 2 chambers: scala vestibuli (connected to oval window) and helicotrema (region at apex of cochlea where scala vestibuli and scala tympani are continuous)
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Spiral organ of corti
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inside cochlear duct (scala media), receptor epithelium for hearing, consists of supporting cells are columnar epithelium, inner (transmit vibrations of basilar membrane) and outer (3 layers that actively tune cochlea and amplify signal) hair cells, stereocilia (tips of hairs) embedded in gel-like tectorial membrane, hair cells synapse with sensory fibers of cochlear nerve
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Auditory pathway from organ of corti in cochlea
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spiral organ of corti to spiral ganglion of cochlear nerve, cochlear nuclei (CN 8) of medulla, superior olivary nucleus of medulla-pons junction, inferior colliculus of midbrain, medial geniculate nucleus of thalamus, primary auditory cortex of temporal lobe
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Conduction deafness
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sound vibrations cannot be conducted to inner ear, ruptured tympanic membrane, otitis media, otosclerosis
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Sensorineural deafness
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results from damage to any part of auditory pathway
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Semicircular canals
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lie posterior and lateral to vestibule, anterior/posterior (in vertical plane) and lateral (horizontal plane) semicircular canals
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Semicircular duct
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snakes through each semicircular canal
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Membranous ampulla
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swelling in semicircular duct, located in bony ampulla, houses crista ampullaris (contains receptor cells of rotational acceleration and supporting cells and receptor hair cells [kinocilium and stereocilia], which project jelly-like cupula)
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Equilibrium pathway
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transmits info on position/movement of head, relayed from receptors in vestibule and semicircular canals of inner ear through vestibular nuclei in medulla to flocculonodular lobe in cerebellum
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Motion sickness
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mismatch of sensory inputs
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Meniere’s syndrome
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equilibrium is greatly disturbed, excessive amounts of endolymph in membranous labyrinth
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