ENT- physiology Flashcards
what is the range of frequencies the average human ear can perceive (Hz)
20 Hz- 20,000 Hz (pitch)
the external ear collects sounds and directs sound waves into where?
the tympanic membrane
what do vibrations in the tympanic membrane stimulate
the ossicular chain of the middle ear
where does the ossicular chain of the middle ear transmit energy to
the cochlea
what does the middle ear act as
an amplifier mechanism
tympanic membrane aka
the eardrum
what is the ratio of the surface area difference between the tympanic membrane and the oval window
18:1
what is the oval window
membrane that separates middle ear from inner ear
hair cells inside the cochlea bend and this leads to what?
depolarisation
which cranial nerve is responsible for transmitting auditory signals
cranial nerve VIII
what does cranial nerve VIII do in hearing?
transmits electrical signals from inner ear to the brain
what is brodmans areas 41/42
specific regions in the brains auditory cortex, located in temporal lobe, specifically superior temporal gyrus
at how many weeks in utero can a foetus hear
18 weeks
at how many weeks in utero can a foetus respond to sound/voice
26 weeks
at birth, how many infants have bilateral severe/profound hearing loss?
1;1,000
many more will have milder losses
how old is a baby when they usually start cooing and recognising mothers voice
3 months old
typically, how old are babies when they start babbling
6 months old
how old is a baby, typically, when they start saying mama/dada
12 months old
how many words should a baby know by age 2
50+ words
what does the vestibular system control
postural equilibrium
coordination of position of head
movement of the eyes
What does the utricle sense in the vestibular system?
horizontal linear movements (eg side to side, forward)
what does the saccule sense in the vestibular system?
vertical linear movements (eg moving up/down)
name the otolith organs
urticle
saccule
the saccule and urticle each contain a sense organ called…?
the macula
the maculae in the saccule and urticle are located how far from each other? (degrees)
90 degrees from each other
what are otoliths
small granules of calcium and protein , aka ear stones
what are otoliths aka
ear stones
what are the semicircular canals
three ring-like extensions from the vestibule
where at the rings of the semicircular canals located
one in horizontal plane
two in vertical plane
what is CN VIII called?
vestibulocochlear nerve
when the head moves, what happens to endolymph and hair cells in the vestibular apparatus
endolymph moves
this causes hair cells to bend
what is CN VIII responsible for
hearing and balance
what is nystagmus
involuntary eye movement
where does the vestibulospinal tract output to
neck
back
leg muscles
what are taste buds responsible for
detecting chemicals in food and sending signals to the brain for interpretation
what type of receptors are taste and smell receptors
chemoreceptors
what does the structure of a taste bud resemble
slices of an orange
what is the lifespan of taste receptor cells
around 10 days
what are taste receptor cells constantly replaced by
basal cells
how are taste receptor cells electrical signals transmitted to the brain
via afferent nerve fibres
which four places are taste buds mainly present
tongue
palate
epiglottis
pharynx
the majority of tastebuds sit where
in the papillae of the tongue
what are the four types of papillae
filliform
fungiform
vallate
foliate
what are the most numerous types of papillae
filiform
which type of papillae do not contain taste buds
filiform
which type of papillae do contain taste buds
fungiform
foliate
vallate
which three cranial nerves are involved in the process of taste
CN VII- facial nerve
CN IX- glossopharyngeal nerve
CN X- vagus nerve
To remember cranial nerves “Oh oh oh to touch and feel virgin girls vag…. and hymen”
olfactory
optic
oculomotor
trochlear
trigeminal
abducent
facial
vestibulocochlear
glossopharyngeal
vagus
accessory
hypoglossal
where is cranial nerve VII (facial nerve) located in relation to taste sensation
anterior 2/3 of tongue
where is cranial nerve IX (glossopharyngeal) located in relation to taste sensation
posterior 1/3 of tongue
where is cranial nerve X (vagus) located in relation to taste sensation
areas other than tongue, eg epiglottis and pharynx
what are the 5 primary tastes
bitter
sour
sweet
salty
umami (meat or savoury)
what primary taste would alkaloids taste like
bitter
what primary taste would acids taste like
sour
what is aguesia
loss of taste function
what is hypoguesia
reduced taste function
what is dysguesia
distortion of taste function
what is the main cranial nerve involved in smell
olfactory nerve (CN I)
what does the olfactory nerve (CN I) do in relation to smell
mediates common odours
what does the trigeminal nerve (CN V) do in relation to the nose
has a chemical and non-chemical stimulus
protective effect
which type of epithelium is the olfactory neuroepithelium composed of
pseudostraified columnar epithelium
what is the lifespan of olfactory receptors
~ 2 months
Which neurotransmitters are primarily involved in transmitting olfactory signals?
glutamine
dopamine
what is anosmia
inability to smell
what is hyposmia
reduced ability to smell
what is dysosmia
altered sense of smell
what is phantosmia
smell perceived in the absence of stimulus (olfactory hallucination)
what is the stimulant of sweet taste
glucose
what are the stimulants of savoury taste
glutamate
amino acids
which mucosa is associated with smell
olfactory mucosa
what are the three main types of cells located in olfactory mucosa
olfactory receptor cell
supporting cell
basal cell
in ordered to be smelled, a substance must be what
sufficiently volatile (can enter nose with inspired air)
sufficiently water soluble
what does sound frequency dictate
frequency = pitch of sound
what does sound amplitude dictate
amplitude = intensity/loudness of sound
what type of gland is a salivary gland
exocrine gland
what are the three major salivary glands
parotid
submandibular
sublingual
which type of epithelium is found in the throat
resp or squamous epithelium depending on site
which type of epithelium is found in the nose
nose, sinus etc- resp
nasal vestibule- squamous
what are the two primary components of salivary glands and name three cells found in these components
acinar component
ductal component
- serous cells
- mucous cells
- myoepithelial cells
how do serous cells stain
darkly staining
how do mucous cells stain
clear grey staining
what do serous cells contain
digestive enzymes including amylase
what do mucous cells contain
glycoproteins
what structures make up the middle ear
tympanic membrane
malleus
incus
stapes
oval window
Eustachian tube
what three tiny bones make up the ossicular chain of the middle ear
malleus
incus
stapes
is the malleus attached to the tympanic membrane
yes
what is the function of the eustachian tube
air pressure equaliser + ventilator for middle ear mucosa
is the Eustachian tube open/closed at rest
closed
what are the two openings from the middle ear to the cochlea (inner ear)
oval window
round window
what two structures make up the inner ear
cochlea
vestibular sytem
what is the fluid system that suspends the otic capsule called
perilymph
list the central pathways for sound (ECOLI)
eight cranial nerve
cochlear nucleus
olivary complex
lateral lemniscus
inferior colliculus
