A&P 2 Special Senses

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