chapter 15 bold words

olfaction

initiated at olfactory epithelium

basal cells

stems cells that continually replace olfactory neurons; lifespan of 30-60 days

supporting cells

columnar cells that surround olfactory neurons

olfactory nerve (CN I)

combined axons of olfactory neurons

olfactory bulb

structure that sits above cribriform plate of ethmoid bone, inferior to frontal lobe of brain

olfactory tract

composed of axons that exit olfactory bulb; travel to other regions of CNS for interpretation

odorants

in inhaled air are detected by olfactory neurons

activation of olfactory receptors

odorants are dissolved in mucus surrounding olfactory neuron’s cilia

odorant-binding proteins

transport odorants through mucus to receptors on cilia of olfactory neuron

anosmia

lack of olfaction

hyposmia

reduced olfactory sensitivity

gustatory sense or taste

involves chemoreceptors that are stimulated by various chemicals

taste buds

tongue is covered with rounded projections called papillae

taste sensations

taste relies on detection of five classes of chemicals sweet, sour, salty, bitter, umami

taste receptors

classified by substance they detect, with only one type of receptor associated with an individual gustatory cell

activation of taste receptors

substance must dissolve in saliva before it can reach a taste bud where it may be deteced as a gustatory stimulus

eyeballs

located in orbits on either side of nasal cavity

cavities and chambers of eye

eyeball is divided into anterior and posterior cavities by lens and ciliary body

posterior cavity

larger cavity found behind lens; filled with a gelatinous material called vitreous humor

vitreous humor

made mostly of collagen and water; presses retina against choroid and helps maintain eyeball shape

anterior cavity

in front of lens and ciliary body; further divided into anterior and posterior chambers

posterior chamber

between lens and iris

anterior chamber

between iris and cornea

aqueous humor

both anterior and posterior chambers are filled with it

aqueous humor

watery fluid secreted by ciliary body; flows from posterior chamber through the pupil into anterior chamber

scleral venous sinus

blood vessel network found at anterior edge of iris; drains aqueous humor out of anterior chamber

glaucoma

aqueous humor cannot drain fluid builds up in anterior and posterior chambers

vision

perception of light reflected by various objects

emmetropic state

eye is relaxed and focusing on distant objects

errors of refraction

accommodation has its limits either due to aging lens or shape of eyeball

presbyopia

condition where an indvidual’s near point of accommodation is 10-20 inches or greater

astigmatism

is a condition where the curvature of lens or cornea is irregular and light rays are not evenly refracted

emmetropia

desired situation where length of eyeball is ideal in anterior to posterior directions

hyperopia

condition where eyeball is too short or cornea is too flat

myopia

condition where distance between cornea and lens is too great or cornea is too curved

cones

photoreceptors that function best in bright light for processing high resolution color vision

rods

photoreceptors that do not detect colors

otitis media

inflammation of middle ear cavity

acute otitis media

pharyngotympanic tube acts as a conduit for pathogens in nasopharynx to reach middle ear

cochlear implant

surgically implanting electrodes that bypass damaged hair cells and directly stimulate cochlear nerve

static equilibrium

maintaining balance when head is tilted but head and body are not moving

dynamic equilibrium

maintaining balance when head or body is undergoing rotational or angular motions