Special Senses

Question 1

what are the properties of sound

Answer 1

pure tone is described by two measures -

1. amplitude or intensity measured as sound pressure measured in decibels (dB) –> perceived as loudness
2. frequency or number of cycles per second of vibration, measured in hertz (Hz) and perceived as pitch

Question 2

what are the physical properties of sound

Answer 2

amplitude and frequency and harmonics

Question 3

what are the perceptual properties of sound

Answer 3

loudness and pitch

Question 4

what muscles permit movement of pinna

Answer 4

auricularis muscles (anterior, posterior, superior)

Question 5

what are the two muscles in the middle ear

Answer 5

tensor tympani and stapedius muscles

act to improve perception and sound protection –> both damaging sounds and those that are self produced

Question 6

what are the fluid filled canals in the cochlea

Answer 6

1. vestibuli
2. media
3. tympani

Question 7

what causes vibrations against the oval window in the cochlea

Answer 7

the staples vibrations

causes fluid within the cochlea to move

Question 8

what is the round window

Answer 8

a moveable membrane that is required to accommodate pressure that arises when the oval window is pushed

Question 9

what is the organ of corti

Answer 9

the structure responsible for converting the vibrations produced by the ossicles into neural activity

Question 10

what are the 3 components of the organ of corti

Answer 10

1. sensory cells (hair cells)
2. auditory fibres that make up the vestibulocochlear nerve
3. supporting cells

Question 11

what are the hair cells in the inner ear

Answer 11

both inner and outer

are involved in transmitting the perturbations in the basilar membrane and transmit this information to the vestibulocochlear nerve

Question 12

what are the functions of the inner hair cells

Answer 12

associate with many auditory nerves

involved in sound perception

Question 13

what are the functions of the outer hair cells

Answer 13

associate with few auditory nerves

are not primarily involved in sound detection, instead they fine tune information by changing tension on the basilar membrane (relax or stiffen)

Question 14

what are the efferent projections from brain involved in

Answer 14

to inhibit input from loud sounds

Question 15

what are the neurotransmitters in the inner hair cells

Answer 15

glutamate

Question 16

what are the neurotransmitters in the outer hair cells

Answer 16

acetylcholine

Question 17

what does inner ear hair cell movement cause

Answer 17

hair cell cilia cause rapid changes in ion channels

fast mechanically gated ion channels –> no second messenger systems

respond with graded potentials

channels are large (non-specific) so other cells can enter the cell

Question 18

what is the basilar membrane movement

Answer 18

vibrates in response to sound exhibit a topographical organization

*detect different frequencies in acoustic vibrations

high frequencies cause maximal distortions in base and low frequencies cause large changes at apex

Question 19

what are the auditory pathways that link the brainstem and brain

Answer 19

1. superior olivary nucleus is the first stage when inputs from both the right and left cochlear nuclei are integrated (binaural)
2. the inferior colliculus is the primary auditory center in the midbrain –> this nucleus sends outputs to medial geniculate nuclei (MGN) in the thalamus

MGN then projects to auditory cortex

Question 20

what is the auditory theory –> sound localization via binaural cue

Answer 20

intensity differences

results from the differences in loudness that reaches the ear

head provides a barrier the sound must move around

higher freq sounds are more susceptible to intensity differences compared to low freq sounds (longer sound waves)

Question 21

what are latency differences

Answer 21

results from the difference in the arrival times of sound waves

one ear is always a little closer to sound

thus onset disparity (difference in two ears) and ongoing phase disparity (continuous mismatch of all frequency peaks)

Question 22

what is the auditory theory in mammals

Answer 22

the superior olivary nucleus is the main localization nucleus for sound with two divisions

1. lateral superior olive processes intensity differenec
2. medial superior olive (MSO) processes latency differences but encodes sounds by relative activity of the left and right sides

Question 23

what are common causes of conduction deafness in the external ear and middle ear

Answer 23

1. external ear

cerumen (excessive earwax)

otitis externa (ear infection, aka swimmers)

2. middle ear

fluid accumulation in eustachian tube

Question 24

where does sensorineural deafness originate from

Answer 24

cochlear or auditory nerve lesions

damage to hair cells (ex. outer) can result in tinnitus (a sensation or ringing in ears)

Question 25

what are cochlear implants used to treat

Answer 25

deafness due to hair cell loss

Question 26

what is word deafness

Answer 26

unable to recognize spoken words speech production and simple sound discrimination are still function

Question 27

what is cortical deafness

Answer 27

difficulty in recognizing auditory stimuli rare bilateral damage to the auditory cortex stroke induced damage to various nuclei in the auditory pathway

Question 28

what organ do animals have for olfactory detection

Answer 28

vomeronasal organ

Question 29

what secrete mucous at the olfactory epithelium

Answer 29

bowman's glands secrete mucous that line epithelium

Question 30

what do ordorants have to be

Answer 30

partially lipid soluble odorant receptors are on the cilia

Question 31

what replaces receptors in the olfactory epithelium

Answer 31

basal stem cells

Question 32

how are odorants detected and activate intracellular processes

Answer 32

graded potential and action potentials

Question 33

what are the receptors in the olfactory epithelium and bulb

Answer 33

large number of receptors, small number of mitral cells means sensitivity of mitral cells is very high but spatial awareness of smell origin is poor but improved by lateral inhibition

Question 34

how is olfaction is significantly different from other sensory systems

Answer 34

chemical detection and circuitry olfactory epithelium --\> olfactory bulb --\> limbic system --\> motor pathways

Question 35

what are characteristics of olfaction

Answer 35

1. highly sensitive 2. shows complete adaption 3. complex concentration/perception characteristics

Question 36

why do dogs have a better sense of smell

Answer 36

1. larger olfactory epithelium so more receptors 2. twice as many active receptor proteins 3. olfactory bulb is much larger 4. vomeronasal organ show low functionally in humans

Question 37

where are the taste receptor cells in the tongue

Answer 37

are in buds on papillae in the tongue sensation derives from tastants (molecules giving rise to taste)

Question 38

what are the taste receptors

Answer 38

1. salty 2. sour 3. bitter 4. sweet

Question 39

what are the two types of taste receptors

Answer 39

each cell will have one type of receptors but buds can detect multiple types of tastants (concentrations of each receptor type will differ between buds) 1. small charged particles or ions (salty and sour) --\> enter taste receptor cells through ion channels in microvilli 2. molecules bind to receptor (sweet and bitter)

Question 40

how is taste percieved in dogs

Answer 40

from nasal epithelium --\> olfactory bulb --\> limbic system --\> sensory cortex