Special Senses

Terms	Definitions
special	-all isolated in head
five special senses	olfaction gustation vision equilibrium hearing
olfactory organs	-smell -located in nasal cavity -olfactory epithelium
olfactory epithelium	-olfactory receptors -supporting cells -basal (stem) cells - divide to become olfactory cells or supporting cells
olfactory glands	-secretions absorb water and form a thick, pigmented mucus -coat surfaces of olfactory organs
olfactory receptors	-highly modified neurons -reception involves detecting dissolved chemicals (odorants) as they interact with odorant-binding proteins
olfactory discrimination	-distinguish thousands of chemical stimuli -CNS interprets smells by the pattern of receptor activity
olfactory receptor population	-considerable turnover (about every few weeks) -number of olfactory receptors declines with age
gustation	-provides information about the foods and liquids consumed
gustatory receptors	also, taste receptors -distributed on tongue and portions of pharynx and larynx -clustered into taste buds
taste buds	-lingual (tongue) papillae (projection) on superior surface of tongue -three types of lingual papillae -circumvallate papillae - 100 ~ each -fungiform papillae - 5 ~ each -filiform papillae - provide friction
basal cells	-found in taste buds -transitional (support cells) -gustatory cells - extend taste hairs thru taste pore; survive 10 days
primary taste sensations	-sweet -salty -sour -bitter
secondary taste sensations	umami - beed/chicken broths and parmesan cheese water - detected by water receptors in the pharynx
accessory structures of eye	-provide protection, lubrication, support -palpabrae - eyelids -superficial epithelium of eye - -lacrimal apparatus -
palpabrae	-eyelids -blinking keeps surface of eye lubricated, dust- and debris-free medial canthus and lateral canthus - where two eyelids are connected eyelashes - robust hairs that prevent matter f/ reaching surface of eye tarsal glands - secrete lipid-rich product that helps keep eyelids from sticking together
superficial epithelium of eye	conjunctive epithelium covering - inner surfaces of eyelids (palpebral conjunctiva) and outer surfac of eye (ocular conjunctiva)
lacrimal apparatus	produces, distributes, and removes tears lacrimal glands - tear gland; secretions contain lysozyme, an antibacterial enzyme
layers of eye	-outer fibrous tunic -middle vascular tunic -inner neural tunic
eyeball	-hollow -divided into two cavities -large posterior cavity -small anterior cavity
fibrous tunic	sclera - white of eye cornea - limbus - border between cornea and sclera
vascular tunic	also, uvea functions - -provides route for blood vessels and lymphatics -regulates amount of light entering eye -secretes and reabsorbs aqueous humor -controls shape of lens
vascular tunic II	iris - changes diameter of pupil ciliary body - contains ciliary processes, ciliary muscle that attaches to suspensory ligaments of lens choroid - vascular layer that separates fibrous and neural tunics; delivers oxygen and nutrients to retina
neural tunic	-retina -outer layer called pigmented part -inner neural part - contains visual receptors and associated neurons; rods and cones are types of photoreceptors
rods and cones	rods -most numerous -detect light -no color info -respond to almost any photon, regardless of energy content cones -color -densely clustered in fovea at center of maculalutea -have characteristic ranges of sensitivity phobias centralis -only cones are located here -best place for vision
chambers of eye	-ciliary body and lens divide eye -large posterior cavity (vitreous chamber) -smaller anterior cavity -anterior chamber - extends f/ cornea to iris -posterior chamber - between iris, ciliary body, and lens
smaller anterior cavity	aqueous humor -fluid circulates within eye -diffuses thru walls of anterior chamber into canal of schlemm -re-enters circulation intraocular pressure -fluid pressure in aqueous humor -helps retain eye shape
large posterior cavity	also, vitreous chamber vitreous body -gelatinous mass -helps stabilize eye shape and supports retina
lens	lens epithelia - acts like a sac that lens fibers sit in lens fibers -anterior portion of lens -cells in interior of lens -no nuclei or organelles -filled with crystallins, which provide clarity and focusing power to lens cataract - condition in which lens has lost its transparency
light refraction	-bending of light by cornea and lens focal point -specific point of intersection on retina focal distance -distance between center of lens and focal point
light refraction of lens	accomodation -shape of lens changes to focus image on retina astigmatism -condition where light passing thru cornea and lens is not refracted properly -visual image is distorted visual acuity -clarity of vision -normal rating 20/20 myopic - near-sighted; see close things hyperopic - far-sighted; see far things
anatomy of rods and cones	outer segment -membranous discs visual pigments -where light absorption occurs -rhodopsin -opsin plus retinal -retinal - synthesized from vitamin A inner segment organelles
photoreception	-photon strikes retinal portion of rhodopsin molecule -opsin is activated -bound retinal molecule has two configurations 11-cis form 11-trans form
color vision	-integration of information from red, green, and blue cones color blindness -inability to detect certain colors
field of vision	depth perception -by comparing relative positions of objects between left eye and right eye images
auricle	-surrounds entrance to external acoustic meatus -protects opening of canal -provides directional sensitivity
external acoustic meatus	-ends at tympanic membrane (eardrum) tympanic membrane -thin, semitransparent sheet -separates external ear from middle ear
ceruminous glands	-integumentary glands along external acoustic meatus -secrete waxy material (cerumen) -keeps foreign objects out of tympanic membrane -slows growth of microorganisms in external acoustic meatus
auditory tube	malleus - hammer incus - anvil stapes - stirrup
inner ear	-contains fluid called endolymph -subdivided into vestibule, (3) semicircular canals, cochlea oval window -connected to base of stapes round window
vestibule	-encloses saccule and utricle -receptors provide sensations of gravity and linear acceleration
semicircular canals	-contain semicircular ducts -receptors stimulated by rotation of head
cochlea	-contains cochlear duct (elongated portion of membranous labyrinth) -receptors provide sense of hearing
semicircular ducts	-continuous with utricle -each duct contains ampulla with gelatinous
stereocilia	-resemble long microvilli
ultricle and saccule	-provide equilibrium sensations -maculae -statoconia -otolith - ear stone; gel and statoconia
auditory ossicles	-convert pressure fluctuation in air into much greater pressure fluctuations in perilymph of cochlea
cochlear duct receptors	basilar membrane -separates cochlear duct from tympanic duct
pressure wave	pitch - sensory response to frequency amplitude - intensity of sound wave frequency - number of waves cycle - used instead of wave cps - cycles per second; measures frequency hertz - Hz; unit for measuring frequency intensity - measure of energy in sound wave decibels - sound energy reported in ~ -from softest to loudest a trillion-fold increase occurs -young children have greatest range
age and hearing	-tympanic membrane gets less flexible -articulations between ossicles stiffen -round window may begin to ossify
anatomy of the ear
circulation of aqueous humor
cochlea
external features and accessory structures of the eye
gustatory receptors
image formation
inner ear
middle ear
olfactory organs
organization of retina
saccule and utricle
sectional anatomy of the eye
semicircular ducts
steps in sound and hearing
_______ is nearsightedness, or an ability to see only a short distance	myopia
_______ is farsightedness, or an ability to see only far objects	hyperopia