week 6 Flashcards by Maxwell Field

What is hearing

the sense of detecting sound

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what is sound

from the movement or vibration of objects

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What are the properties of sound

frequency and pitch
amplitude and loudness
complexity and timbre

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What is audition

direct the sound waves into the hearing part of ear
Sense the fluctuation in air pressure
Translate these fluctuations into an electrical signal that your brain can understand

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What is the external ear

captures, focuses and filters sound
Pinnae: funnel-like structure channels sound into the ear
Ear canal: narrowing amplifies sound waves toward eardrum (tympanic membrane)

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what is the middle ear

concentrates/amplifies sound energies
Ossicles= Malleus (Hammer), Incus (Anvil), Stapes (stirrup)

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What is the inner ear

Cochlea
converts vibrational energy into waves of fluid
the auditory part of the vestibulocochlear nerve

Also includes- vestibular apparatus and eustachian tube

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What is cochlea

coiled structure, bony exterior, hollow compartments
Vibrations from the ossicles to oval window membrane sends waves through fluid filled cochlea
Vibration is transmitted to organ of Corti via Basilar membrane
Movement of sensory hair cells transduce sound waves into neural activity, which is sent along auditory nerve to the brain

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What is Basilar membrane

vibrates when the stapes moves the fluids of the inner ear. Different sound wave frequencies cause peak pending of the membrane at different point along its length

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What is Organ of Corti

sends vibrations to auditory nerve

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what is the auditory pathway to brain

ear (cochlea)-> cochlear (brainstem)-> superior olive (brainstem)-> inferior colliculi (midbrain)-> medial geniculate nucleus (thalamus)-> Auditory cortex (temporal cortex)

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what is auditory cortex

primary auditory cortex- Temporal lobe, lies within Heschl’s gyrus, within sylvian fissure , tonotopic

Secondary cortex: surrounds primary aud. cortex, Planum temporale, behind HG, and superior

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What is hearing pitch

enabled by tonotopic organisation: each hair responds to a small range of frequencies based on location on basilar membrane

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What is temporal coding

the rate of sound waves

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What is hearing loudness

intensity sound wave amplitude, larger pressure changes produce more intense basilar vibration
greater shearing of hair cells
cochlear bipolar neurons fire more frequently

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how does hearing detect location

Difference in timing at each ear
Relative loudness
Detected by nuclei in the brainstem that receive input from both L&R ventral cochlear nuclei:
Superior Olive (medial part) neurons respond to difference in arrival time between each ear
Superior Olive (lateral part) and trapezoid body neurons respond to differences in loudness

what is hearing loss

decreased sensitivity to sound

What is deafness

loss of hearing; speech not perceivable with hearing aids

What is conduction deafness

pathology of the outer/middle ear: prevent vibrations reaching cochlear

What is sensorineural deafness

Originate from cochlear or auditory nerve lesions
Cochlear losses most common

What is age related hearing loss (prebycusis)

affects 70% of over 65s
Many potential causes
usually changes to inner ear: slow decay and or damage to sensory hair cells

Damage to auditory cortex

Left primary cortex damage : deficit in differentiating speech sounds
eight primary auditory cortex damage : deficit in discriminating musical sounds
Bilateral auditory cortex damage: everything sound the same is confused

What is chemoreception

oldest sensory system
detects presence of specific chemicals and works with taste to create flavour

What is Olfaction

Hardest sense to describe an seems to be about familiarity recognition
Olfactory receptors: large, diverse set olfactory receptors coded in 350 genes, allowing differentiation of 10,000+ smells

What is Nasal cavity

has a respiratory segment and olfactory segment Olfactory segment along the roof of the nasal cavity lined with olfactory epithelium

What is olfactory receptor

the olfactory epithelium=receptor surface have a short thick dendrite ending in 10 to 20 cilia, that projects into a mucous layer

What is the pathway to the brain for the olfactory bulbs

receptor cells project to olfactory, olfactory nerves are non-myelinated and are in bundles forming olfactory cranial nerve receptors form synapses with dendrites of mitral cells at glomeruli

How does signal get sent from olfactory bulb to the brain

Mitral cells send axons from olfactory bulb to a broad range of forebrain areas (amygdala, pyriform cortex and orbitofrontal cortex)

Abnormalities of olfaction

Anosmia(absence of the sense of smell)-can be anosmic for certain odour, can be temporary or permanent Hyposmia(diminished olfactory sensitivity)- hyposmia might be very early sign of Parkinson's disease Dysosima(distorted sense of smell)- misinterpreted smells or hallucination of smell

What is the tongue

muscular organ and the primary organ of gustation Upper surface of the tongue is covered in papillae and tast buds

What is taste receptors

taste buds are the sense organ for taste. found on and under our tongue, on soft palate: 5 types sweet, sour, salty, bitter and umami. chemicals from the food must first dissolve in saliva

What is taste

stimuli interact with receptors tips genetic differences in ability to detect bitterness

Where does the nerve signal go from the taste buds

Nerve fibres travel from taste buds to the brain stem via cranial nerves

What is the second pathway to brain

projects through pons to hypothalamus and amygdala

What is the pathway to brain part 1

through posterior medulla to ventroposterior medial nucleus of thalamus From there ether goes to -> primary somatosensory cortex (tactile information), Gustatory cortex of the insula (flavour)

What are abnormalities of taste

Ageusia(absence of the sense of taste)- it may be caused due to cranial nerve damage or problems with endocrine system Hypogeusia(diminished taste sensitivity)- often due to medication Dysgeusia(disturbed sense of taste)- diagnosis is usually complicated since of taste is tied together with other sensory systems. various potential causes and treatments