4 senses Flashcards

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1
Q

why are the senses important

A

adaptive significance

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2
Q

adaptation

A

ie/ neurons becoming less responsive over time

for example, a clock ticking in the background slowly goes away

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3
Q

pinna

A

external ear or external auditory meatus

captures, focuses and filters sound

they are directional - ears point in a specific direction which aids in localization - figuring out where the sound is coming from

highly mobile in some species

performs early sound processing - pattern of ridges inside act as a spectral filter - increasing and decreasing certain sound frequencies

directs sound waves into ears

guides them into ear canal - leading to middle ear

act as radiators - heavily vascular in some species

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4
Q

meatus

A

hole from outside to inside

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5
Q

middle ear

A

tympanum and ossicles

concentrates sound energy

breeding ground for bacteria, pressure is painful, subject to infection

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6
Q

tympanum

A

eardrum

membrane that seals the end of the ear canal + ossicles

vibrates when struck by sound waves from ear canal - converts sound energy into a form of kinetic energy

when ruptured hearing is impaired

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7
Q

ossicles

A

tiny bones - chain of them

smallest bones in your body

three of them

concentrate and amplify vibrations focusing pressure on small oval window

amplification is important for converting vibration in air into movements of fluid in the middle ear

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8
Q

what are the 3 ossicles

A

malleus (hammer), incus (anvil) and the stapes (stirrup)

form an articulated chain (leading from back of ear to cochlea (inner ear)) - mechanically coupling the vibrating tympanum to inner ear (oval window)

for the tymphanum to vibrate, air pressure must be equal on both sides - middle ear contains eustachian tube

if middle ear is tighter than ear is tighter than ear drum, sound waves can not move as freely

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9
Q

eustachian tube

A

in middle ear

localizes pressure

leads away to the oral- nasal cavity - this is how ear infections get in

connects to let air in and out

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10
Q

middle ear muscles

A

tensor tympani
stapedius

attach to the end of ossicles

contraction of the muscles alters the ability of the ossicles to move in response to a vibrating tympanum

has a modulating movement of the ossicles , reducing the amount of response to sounds

makes the bones stiffer and less sinsitive

activate just before we produce a self made sound ie/ speech, cough - hence why we do not think our own sounds are crazy loud

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11
Q

tensor tympani

A

is a tiny muscle connected to the malleus, which is the ossicle attached to the tympanum (makes this tight)

sound waves strike here and cause it to vibrate at the same frequency as the sound.

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12
Q

stapedius

A

connects the stapes to the floor of the middle ear

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13
Q

modulation of sound

A

occurs within 200 msec of a loud noise

happens with our own voice

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14
Q

oval window

A

where the stapes connects to the cochlea

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15
Q

sound

A

vibrational energy that in a series of compressions

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16
Q

decibel

A

measure of sound frequency perceived as loudness

perception of amplitude

perceived as a local increase or increase in air pressure

plotted as a sine wave

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17
Q

sound emitters

A

produce successive compressions are rarefactions in air - think of a loudspeaker cone

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18
Q

frequency

A

time from peak to peak

pitch Hz or cycles/sec

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19
Q

amplitude

A

peak height

loudness

db is relative

volume, how loud is the sound (strength)

intensity force sound exerts per unit area

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20
Q

harmonics

A

are multiples of the fundamental frequency of an emitter

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21
Q

fundamental frequency

A

predominant frequency of an auditory tone

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22
Q

timbre

A

is the unique “signature” sound of an emitter, comprised of the fundamental frequencies plus harmonics (or overtones)

character of the sound of an instruments

ie/ we know the sound of different instruments like piano/guitar (knowing they sound different)

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23
Q

doppler shift

A

occurs if the emitter is in motion

velocity (ie/ how an ambulance sounds far vs. away is added to the rarefraction-compression cycle to change

used by many species, especially bats

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24
Q

resonance

A

intensity of a vibration

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25
Q

pure tone

A

a tone with a singer frequency of vibration (frequency and amplitude)

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26
Q

transduction

A

converting from one form of energy to another

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27
Q

the inner ear

A

the organ that actually encodes the sound of elements

called a transducer

only the size of a pea

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28
Q

cochlea

A

fluid filled

converting sound waves from the world into something we can understand (neural activity)

fluids that fill is are not compressible

vibrations transmitted from the tympanum are communicated to the endolymph via the action of the stapes against the oval window

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29
Q

what are the gel fluids that fill the cochlear tubes

A

endolymph and perilymph

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30
Q

oval window

A

connection point of ossicles (stapes) to the cochlea

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31
Q

the fluid in the cochlea is not compressible, what does this cause?

A

there is movement (waves) produced in the endolymph - this propagates through the length of the cochlea

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32
Q

round window

A

bulges to accommodate the pressure that comes from the compressed fluid

lets energy out of the cochlea

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33
Q

organ of corti

A

transduces sound waves into neural energy

receptor system

the most important part of the cochlea for hearing

converts vibration from sound into neural activity

consists of auditory sensory cells (hair cells), elaborate framework of support cells, auditory nerve terminals that transmit neural signals to and from the brain

basiliar membrane and tectorial membrane

waves are created in the fluid of the scala vestibula causing the basilar membrane to ripple

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34
Q

vestibulocochlear nerve

A

fibers contact the bases of hair cells

some fibers convey sound info to the brain

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35
Q

where is the organ of corti located

A

in the scala media (middle canal of the 3 parallel

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36
Q

basilar membrane

A

middle canal

one of the membrane that divides the tubes of the cochlea

base: increased frequency, stiff
apex: decrease frequency

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37
Q

hair cells

A

rows of specialized receptors

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38
Q

inner hair cells

A

sterocilia protrude from top of hair cell

closer to central axis

base near basiliar membrane

when stimulated, release glutamate onto auditory nervefibers

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39
Q

stereocilia

A

tiny bristle

nesstles into hollows of tectorial membrane
- form mechanical bridge between two membranes
- forced to bend when sounds cause basiliar membrane to ripple

approximate the tectorial membrane

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40
Q

tectorial membrane

A

another divider

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41
Q

depolarization of hair cells

A

even a tiny bend in stereocilia causes a large depolarization of the hair cells

causes the operation of a special type of large and selective ion channels
- allows rush of potassium and calcium in at the base

causes synaptic vesicles to fuse with synaptic membrane and release neurotransmitters to stimulate adjacent nerve fibers

hair cells sway back, stereocilia shuts

the opening and shutting of channels is a way of encoding frequency

depolarization reaching the base of the hair cell causes a calcium channel to open - resulting calcium current provokes transmitter release

the transmitter acts on the auditory nerves leading from the hair cells to the brain

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42
Q

outer hair cells

A

12000
in 3 rows arranged in parallel

same arrangement of stereocilia

release ACh and are influenced by GABA (inhibatory NT)

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43
Q

hair cells ability to switch on and off

A

allows them to track the rapid oscillation of the basiliar membrane

hair cells are sensitive

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44
Q

how does the organ of corti work?

A
  1. ossicles transmit vibrations to the fluid of the cochlea, setting up traveling waves
  2. waves cause the basilar membrane to ripple - like the shaking of a carpet
  3. hair cells have their bases in the basilar membrane, and their stereocilia inserted into the tectorial membrane above
  4. for any frequency, amplitude of the traveling wave is exaggerated at one particular location of the basilar membrane, due to a prcess akin to resonance

energy is put into the base of the basiliar membrane which is at the stapes which vibrates the round window to go into the membrane

high frequency and smaller response at base
low frequency and heightened response in apex

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45
Q

IHC - afferent

A

leads to brain

carries info that we perceive as sound

activated by glutamate from the IHS

convey APs to the brain that provide perception of sound info

95 percent of fibers leading to brain

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46
Q

IHC - efferent

A

from brain to IHC

serve a modulatory function (influences how hair cells are) by inhibiting the IHC - afferent fibres. ACh

allow brain to control responsiveness of IHC’s

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47
Q

OHC - afferent

A

from OHC to brain

small diameter fibres using ACh

convey info about activity/mechanical state of basilar membrane (moment to moment state)

not thought to be involved in conscious perception of sound

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48
Q

OHC - efferent

A

from brain to OHC

using GABA, alter the responsiveness of OHC

tuning to make sharper, amplified

can change their length - can modify the stiffness of the regions of the basilar membrane - resulting in sharper tuning and amplification

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49
Q

what does movement of basilar membrane do to stereocilia

A

causes a deformation and benidng

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50
Q

tip link

A

connects hair cells

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51
Q

tuning

A

basilar membrane is tuned by virtue of its changing width but not enough to explain discrimination of 2 Hz

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52
Q

Neural tuning

A

at higher levels, inputs from numerous auditory fibers (combine and go to brain which increases tuning) converge on neural systems that determine (filter) the frequency of received sound

individual neurons in brain respond selectively to particular frequencies and are inhibited by neighbouring frequencies

53
Q

lateral inhibition

A

to sharpen own response will surpress the responses to neighbours

sharpens focus on most central frequency

54
Q

electromechanical tuning

A

OHC’s can instantaneously change their length - this changes the responsiveness of the basilar membrane

OHC action amplifies basilar membrane response, sharpening tuning

thus, the basilar membrane is active, rather than passive

55
Q

otoacoustic emissions

A

the active nature of the cochlea causes it to emit clicks under certain conditions (just as a microphone can act as a speaker under some conditions)

20 db

56
Q

evokes otoacoustic emissions

A

provoked by presented sounds

useful for testing hearing in infants, effects of drugs on hearing, experiments on basic cochlear mechanisms

57
Q

spontaneous otoacoustic emissions

A

people that have a good sense of hearing

fair chance that you cochlea are producing spontaneous clicks, but you can not hear them

associated with especially sensitive hearing

females make more

more common in right here thereform left hemisphere (asymmetry)

58
Q

left hemisphere

A

specialized for language and connected to right cochlea

59
Q

major centers in higher brain structures for hearing (in order)

A

cochlear nuclei
superior olivary complex
inferior colliculus
medial geniculate
auditory cortex

60
Q

tonotopic arrangement

A

map of frequencies of a specific location

orderly map

from low to high frequency

precision allows for sharper tuning - differentiating between sounds

auditory neurons are excited by some frequencies and inhibited by others

61
Q

cochlear nuclei

A

brainstem

first receiving center in brain - some initial processing

low level integration, tuning and projection to other brain areas

where auditory nerve fibers terminate

receive input from auditory hair cells

output projects to superior olivary complex

62
Q

superior olivary complex

A

located in brainstem

receives and integrates inputs from both cochlea

basis of binaural (stereo) hearing - first part of brain that does this

localizes sound by comparing the two ears

passes info to inferior colliculus

63
Q

inferior colliculus

A

midbrain

tuning

spatial localization (where sound came from) for some species

primary auditory centers of midbrain

output goes to medial geniculate

64
Q

medial geniculate

A

part of the thalamus

outputs extend to many auditory cortical areas

projects to the auditory cortex

65
Q

auditory cortex

A

superior temporal cortex (primary auditory area)

integrates non-auditory info with sound

conscious perception of sound

66
Q

pitch discrimination

A

we can typically hear sounds for 20 Hz to 20,000Hz

subjective, frequency (physical property of sound) is absolute

place theory

volley theory

67
Q

place theory

A

that perceived pitch corresponds to the location on the basilar membrane that is most strongly activated

how it vibrates at certain spots, location of activated hair cells

example of labeled lines each neuron fires in response to its faveourite frequency

68
Q

treble

A

increased frequency

base

69
Q

bass

A

decreased frequency

apex

70
Q

volley theory

A

that pitch is a function of the rate of firing in auditory fibres

500hz= 500AP bending corresponds to the amount of APs

71
Q

infrasound

A

less that 20Hz (elephants and whales)

72
Q

ultrasounds

A

more than 20,000 Hz (bats and porpoises)

73
Q

sound localization

A

evolutionary significance

binaural (2 ear) cues are the best and most obvious

74
Q

intensity difference

A

how loud the sound is

for a sound off the midline, one ear is closer than the other to the source

this results in differences in the amplitude of sound received by the two ears (comparison between them)

noise level will vary between ears - helps us localize sound

75
Q

head shadow

A

the head blocks sound from getting to the more distant ear, exaggerating the intensity difference

difference more pronounced at higher frequency

76
Q

time of arrival

A

when a sound is produced the initial sound waves arrive later at the more distant ear - arrive at one ear before the other

one ear a little closer to the source

the difference in arrival time at the two ears is directly related to the angle of the sound source (but could be in front of or behind the head, in the absence of other cues)

77
Q

phase differences

A

related to time of arrival (peaks and troughs)

for an ongoing sound, the peaks and troughs of the sound wave (compressions and rarefactions) have to go farther to hit the more distant ear, and thus arrive a little later (out of phase)

the auditory system can compare the degree of phase discrepancy for an ongoing sound - the greater the discrepancy, the greater the angle of the sound source

78
Q

onset disparity

A

difference between two ears in hearing beginning of the sound

79
Q

ongoing phase disparity

A

continuing mismatch in two ears between time of arrival of all peaks and troughs that make up the sound wave

80
Q

ear meat effects

A

direction of the pinna discriminates from front to back

some animals can swivel the pinnae to locate the sound source

spectral changes can reveal up-down info

81
Q

cortical areas

A

extracting biologically relevant info

recognizing important sounds: footsteps, animal calls, vocals of familiar vs. unfamiliar people

81
Q

spectral filtering

A

external ear provides another localization cue - hills and valley

82
Q

left-right asymmetry

A

planum temporale: bigger on the left possibly due to left hemisphere speech specializations

many music function of right

some language on right side, and some music on left

83
Q

amusia

A

disorder characterized by the inability to discern tunes accurately to sing

abnormal function in the right frontal lobe and impovershed connectivity between frontal and temporal cortex

can’t access pitch info

84
Q

what are the three types of deafness

A

conduction
sensorineural
central

85
Q

deafness

A

can prevent sound waves from reaching cochlea, trouble converting sound waves to APs and dysfunction of brain regions that process sound

hearing loss so profound that speech cannot be perceived even with the use of hearing aids

86
Q

conduction deafness

A

normally a problem with the ossicles

middle ear problem - sound blocks vibrations from reaching inner ear

can have ossicles removed

partially or fully fused with aging

ossicles become fused together and vibrations of the eardrum can no longer by conveyed to the oval window of the cochlea

87
Q

sensorineural deafness

A

often cochlear

main sort of hearing loss - hair cells blown over like a bunch of tiny trees

ringing that never goess away

headphones, gunshots , car stereos are especially bad

tinnitus

hair cells fail to convert the basilar membrane ripples into volleys of Aps that inform

most often results of permanent damage of hair cells - can happen because of being exposed toloud sounds or from birth - maybe infection

88
Q

tinnitus

A

long term exposure to loud sounds, causing ringing in the ears

89
Q

central deafness

A

arising from brain damage

damage to auditory brain structures can affect hearing in various ways

impaired by perception of behaviour relevant sounds

ie/ strokes, tumours, traumatic injury

90
Q

word deafness

A

selective trouble with speech sounds despite normal speech and normal hearing for nonverbal sounds

91
Q

cortical deafness

A

rare, bilateral lesions of auditory cortex

struggle to recognize all complex sounds (verbal and non verbal)

more complete impairness

92
Q

hearing loss

A

moderate to severe sensitive sensitivity to sound

93
Q

vestibular system

A

system lies in hollow spaces in the temporal lobe

awareness of motion allowing for planning of future movement and anticipate changes due to the movement of the had

have strong connections to the brain

source of motion sickness - may be an adaptation for dealing with poisoning

sense of balance - product of inner ear that adjoin cochlea

94
Q

where do vestibular system fibres terminate

A

in vestibular nuclei while some project to cerrebellum to aid motor programming - outputs project to motor areas of the brain

95
Q

3 semicircular canals

A

in vestibular system

each in different planes

work together to track the movement of the body

fluid filled

movement of head in one direction causes fluid to circulate

ampulla

otoliths

receptrs are hair cells - bending produces APs

96
Q

planes of rotation for the three semicircular canals

A

pitch - nodding up and down
yaw - shaking head side to side
roll - tilting head left/right

97
Q

ampulla

A

buldge, base

hair cells translate fluid movement in neaural signal (action potentials)

cilia embedded here - bending cilia in ampulla signals to the brain that the head has moved. movement of the head creates a flow of fluid that bends the stereocilia

98
Q

otoliths

A

overlie the hair cells, and amplify the effect of them

earstone - mass lags slightly when the head moves

react to gravity and inertia

made of calcium carbonate - theory rhat it may be dissolved by alcohol making us feel spinner

99
Q

saccule and utricle

A

fluid filled cavity

code the position of head when not moving

bulbs

located in ends of semicircular canals

each have an othilic membrane

100
Q

motion sickness

A

experience of nausea because of unnatural passive movement - movement of the body we can not control

too much vestibular stimulation

ie/ passengers in the car are more likely to get it than the driver (not in control)

101
Q

sensory conflict theory

A

we feel bad when we receive contradicting sensory messages - especially between visual and vestibular

hypothesis is that stimulation activates a system originally evolved to rid the body of swallowed poison

little evidence, remains a mystery

102
Q

somatogravic illusion

A

in conditions of low visability, acceleration may be determined as an upward tilt of the plane

103
Q

tongue

A

possesses sensory cells for pain, touch and temperature

104
Q

taste buds

A

between papillae in the walls

50-150 taste receptor cells that detect taste

105
Q

papillae

A

tiny lumps on the tongue that increase SA of the tongue

106
Q

taste cells

A

have microvilli that extend from them into a tiny pore, where they come into contact with

sensitive to tastants

1/5 of basic tastes

life span= 10-14 days - constantly being replaced

anything dissolved in the saliva can get here

107
Q

fungiform papillae

A

mushrooms

usually one taste bud each

108
Q

foliate papillae

A

sides of the tongue

multiple taste buds

109
Q

circumvallate papillae

A

big suckers at the back of the tongue

multiple taste buds

110
Q

kokumi

A

only some people have

primary fat taste

111
Q

what are the five basic tastes

A

sweet, salty, sour, bitter and umami

112
Q

which tastes need simple ion channels

A

salt and sour

113
Q

salt

A

simple ion pore tht admits sodium ions from NaCL

cells have sodium channels, they will enter and create a signal

causes a depolarization and release of neurotransmitter

pore is also sensitive to Cl

TRPV1 - secondary salt sense, can also sense heat

114
Q

sour

A

derive from acids which release H+ ions

ions block potassium channels on the tastebud cells

acid in foods taste sour - more acidic the food the more sour it tastes

115
Q

sweet

A

a type of metabotropic receptor

GPCR - recptor activating 2nd messenger system

T1R2 + T1R3 - combine to make a receptor that detects sweet

116
Q

bitter

A

metabotropic type receptor

important biological system - posions

T2R’s

exhibit broadly tuned sensitivity to any bitter substance - evolved as a poison detector family

often signals in the presense of toxins

117
Q

unami

A

glutamate receptor

T1R1 + T1R3 dimer (GPCR)

closely related to sweet

meaty, savour flavour

responds to amino acids and glutamate

MSG

118
Q

where does taste project from

A

extends from tongue to several brainstem nuclei and then to thalamus, then to gustatory region of the somatosensory cortex

119
Q

taste is a labeled line system

A

selectively inactivating taste cells expressing for one taste that does not effect the others

120
Q

olfaction

A

odour perceptions

requires stronger stimulation for humans

forms the lining of the nasal cavity

121
Q

what are the three major cell types in the olfactory system

A

support cells
basal cells
olfactory receptor cells (main)

122
Q

odorants

A

dissolve into the mucousal layer and interact with receptors of the dendritic cilia

GPCRS is the second messenger system that responds to odours

123
Q

olfactory neurons go into

A

olfactory bulb and then to glomerulus with tunes and sharpens and then organizes them into a tonotropic map

124
Q

mitral cells

A

convey olfactory info to the brain

extends from glomerulus

125
Q

targets for olfactions

A

does not go through thalamus

targets are hypothalamus, amygdala and prepyriform cortex

126
Q

regeneration in olfaction

A

olfactory cells are constantly being replaced

adaption to chemical attack and viruses

basal cells convert to neurons

127
Q

ensheathing cells

A

similar to glial cells

stem cells at the location of injury get 10 percent of function back into the spinal cord

128
Q

pseudogenes

A

resemble genes similar to other species