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olfaction
sense of smell
olfactory epithelium
occupies the superior part of the nasal cavity, covering the inferior surface of the cribriform plate and extending along the superior nasal concha; consists of three kinds of cells: olfactory sensory neurons, supporting epithelial cells, and basal epithelial cells
olfactory sensory neurons
first order neurons of the olfactory pathway
olfactory cilia
sites of olfactory transduction
olfactory receptor
detect inhaled chemicals; within plasma membranes of olfactory cilia
supporting epithelial cells
columnar epithelial cells of the mucous membrane lining the nose; provide physical support, nourishment, and electrical insulation for the olfactory sensory neurons and help detoxify chemicals that come in contact with the olfactory epithelium
basal epithelial cells
stem cells located between the bases of the supporting epithelial cells; continually undergo cell division (mitosis) to produce new olfactory sensory neurons
olfactory (Bowman’s) glands
produce mucus that is used to dissolve odorants (odor molecules) so that transduction can occur
chemoreceptors
what are the receptors in the nose called?
bypass thalamus
what is special about olfaction’s sensory pathway? (something it misses)
olfactory transduction
binding of an odorant molecule to a olfactory receptor protein
gustation
sense of taste
salty, sour, sweet, bitter, umami
five main senses of taste
vallate papillae
type of papillae that is large, v-shaped at the back of the tongue housing 100-300 taste buds
fungiform papillae
type of mushroom-shaped papillae that is scattered over the tongue (5 taste buds each)
foliate papillae
type of papillae on lateral sides of the tongue looks like leaves; degenerate in early childhood because made for milk reception
filiform papillae
type of papillae that has no taste buds but contains tactile receptors, covers the entire surface of the tongue, increases friction to make it easier for the tongue to move food
tastants
Chemicals that stimulate gustatory epithelial cells
facial (VII) nerve
nerve that serves the taste buds in front 2/3 of the tongue
glossopharyngeal (IX) nerve
nerve that serves taste buds in posterior 1/3 of the tongue
vagus (X) nerve
serves taste buds in the throat and epiglottis
vision
the act of seeing
electromagnetic radiation
energy in the form of waves that radiates from the sun
visible light
the part of the electromagnetic spectrum with wavelengths ranging from about 400 to 700 nm
lacrimal apparatus
a group of structures that produces and drains lacrimal fluid or tears in a process called lacrimation
photoreceptors
the type of receptors that are in the eye (rods & cones)
rods
type of photoreceptor that allows for vision in dim light; only does B&W and gray vision; also helps with depth perception
cones
type of photoreceptor that produces color vision; RGB colors, most vision has to do with this type of receptor
wavelength
the distance between two consecutive peaks of an electromagnetic wave
accessory structures of the eye
eyelids, eyelashes, eyebrows, lacrimal apparatus, extrinsic eye muscles
palpebral muscles
muscles that help control eye lid movement; helps open and close eye
extrinsic eye muscles
muscles that are responsible for moving the eyeball itself in all directions
conjunctiva
a thin, protective mucous membrane that lines the eyelids and covers the sclera
conjunctivitis
infection of the conjunctiva; also known as pink eye
fibrous tunic
a tunic (coat) of the eyeball that contains the cornea and the sclera
vascular tunic
a tunic (coat) of the eyeball that contains the choroid, ciliary body and the iris
glaucoma
the build up of interocular eye pressure
fovea centralis
area in the macula lutea with the highest concentration of cones and therefore highest visual acuity
opthalamoscope
instrument to view the vascularization of the retina
blind spot
the point at which the optic nerve exits the eye; aka the Optic disc
anterior cavity
contains the anterior chamber and posterior chamber
anterior chamber
area between the iris and cornea that is filled with aqueous humor
posterior chamber
area that lies behind the iris and in front of the leans and is also filled with aqueous humor
posterior cavity
aka the vitreous chamber; filled with a transparent gelatinous substance, the vitreous humor
Myopia
nearsightedness; eyeball is longer than it should, see close but not far
concave
lens shape used to fix myopia/nearsightedness
hyperopia
aka farsightedness or hypermetropia; eyeball shorter than it should be; image is behind the retina; can see far but not close
convex
lens type that is used to correct hyperopia/farsightedness
astigmatism
abnormality where the cornea or lens has an irregular curve; blurred or distorted vision
presbyopia
degenerative disease of the eye; lens loses elasticity & has difficulty focusing on close objects; difficulty adjusting to changes in lightning
accommodation
ability of the eye to change curvature of lens by adjusting fibers and allowing eyes to keep focus even on moving objects
emmetropic
when an eye has normal (20/20) vision, refracts light correctly and focus clear image on the retina
rhodopsin
a g-couple protein receptor and most abundantly found in rod cells, sense light, allows eye to see in B & W in dim light
Binocular vision
vision in which both eyes are used together, input from both eyes
photobleaching
a process for rods in which light is absorbed creates isomerization of cis-retinal to trans-retinal which causes chemical changes and the production of receptor potential; the change in shape causes separation and therefore the color is changed
light adaptation
this occurs when an individual moves from dark surrounding to light ones; occurs in seconds
dark adaptation
this takes place when one moves from a lighted area to a dark one; takes a minute to complete; has to do with rates of bleaching and regeneration of photopigments in rods and cones
glutamate
inhibitory neurotransmitter that rods release in the dark inhibiting bipolar cells from transmitting signals to ganglion cells which provide output from retina to brain
hemispheric lateralization
the crossing over of signals to the opposite of the brain (ex. signals from the right eye are received in the left side of the occipital lobe)
mechanoreceptors
a type of receptors that detect vibrations; used in hearing
hearing
the ability to perceive sounds
external ear
portion of the ear that contains the auricle (pinna), external auditory canal, and the tympanic membrane (eardrum)
ceruminous glands
glands in the ear that secrete cerumen (earwax) to protect the canal and eardrum
middle ear
a portion of the ear that contains 3 auditory ossicles (malleus, incus, and stapes); sound vibrations transmitted from the eardrum through these 3 bones to oval window
auditory tube
aka pharyngotympanic tube or eustachian tube; extends from the middle ear into the nasopharynx to regulate air pressure in the middle ear
internal ear
aka labyrinth; portion of the ear that contains the cochlea & semicircular canals
cochlea
a bony spiral canal translates vibrations into neural impulses that the brain can interpret as sound
static equilibrium
maintenance of the body’s position relative to the force of gravity (ex. elevator)
dynamic equilibrium
maintenance of the body’s positions in response to sudden movements (ex. rollercoaster)
vestibular apparatus
the organ that maintains equilibrium; includes the saccule, utricle (both otolithic organs), and semicircular canals
otoliths
calcium carbonate crystals; aka ear stones
tinnitus
ringing in the ears
Weber test
Test done by placing the stem of a vibrating tuning fork on the midline of the head and having the patient indicate in which ear the tone can be heard; tests for unilateral deafness
Rinne test
hearing test using a tuning fork; checks for differences in bone conduction and air conduction; tests for sensorineural deafness
Romburg (Balance) test
test done by standing flat with feet both on the ground and eyes closed, then again with one leg up; tests to see if static equilibrium receptors are working
Barany test
rotation test for assessment of vestibular function; testing for nystagmus; can be done by spinning in chair then observing eyes
Conduction deafness
when there is a decreased ability to conduct the energy of sound waves through the external & middle ear to hearing receptors in inner ear; can be due to ear wax build up, damage to tympanic membrane or fusion of auditory ossicles
vertigo
sensation of circular motion either of oneself or external objects; severe cases may be accompanied by nystagmus
scala vestibuli
connected to the oval window; conducts sound vibrations to cochlear duct filled with perilymph & sends pressure waves to scala tympani
genticulate nuclei
in thalamus, moves impulses from medulla oblongata to primary auditory area in temporal love