physiology Flashcards
what is the sense organ of tase
tastebuds
life span of tastebuds
10 days
where are tastebuds found
tongue, palate, epiglottis and pharynx
where are the majority of tastebuds found
in the papillae of the tongue
name the 4 types of papillae of the tongue
filliform, fungiform, vallate and foliate
which type of papilla of the tongue doesn’t contain taste buds
filliform
pathway of tasting
binding of chemical to receptor cells produces depolarising potential
initiates action potential in afferent nerve fibres
signals conveyed by cranial nerves via brainstem and thalamus to cortical gustatory area
name the 5 primary tastes
bitter, sour, salty, sweet and umami
what is aguesia
loss of taste function
what is dysguesia
distortion of taste function
what is hypoguesia
reduced taste function
where is olfactory neuroepithelium found
the olfactory cleft
what is olfactory neuroepithelium composed of
pseudostratified columnar epithelium
name the 4 main cells in olfactory epithelium
basal cells
supporting cells
bi-polar sensory (afferent) neurone
duct cell of bowmans gland
role of basal cells in olfactory neuroepithelium
form the new stem cells from which the new olfactory cells can develop
role of duct cell of bowmans gland in olfactory neuroepithelium
secretes mucous
process of smelling
smell detected by olfactory receptors
axons assemble into bundles of nerves
enter the cranial cavity via the cribiform plate
enter the olfactory bulb which transmits info along the olfactory tract to each temporal lobe and olfactory areas
where is the olfactory bulb located
lies in the olfactory groove within the anterior cranial fossa
approximately how much inspired air reaches the olfactory neuroepithelium
10-15%
how do odorants reach smell receptors during quiet breathing
diffusion
what is the role of mucous (2)
moist and protective environment
aids in dispersing odorants to the olfactory receptors
what is anosmia
inability to smell
what is hyposmia
reduced ability to smell
what is dysosmia
altered sense of smell
what is phantosmia
spell perceived in the absence of a stimulus
name 3 conductive causes of abnormality in smell
nasal polyps
rhinitis
nasal mass
what is used to assess olfaction
UPSIT (scratch and sniff)
name some sensorineural causes of abnormality of smell
viral
head trauma
neurological conditions: parkinsons, dementia
brain tumours
medications
what is sound
a pressure caused by oscillating molecules set in motion by a vibration
what frequency of sound can humans perceive
20-20,000 Hz
role of the middle ear in hearing
amplifies sound
role of the inner ear in hearing
receives mechanical signals and converts them into electrical signals
movement of mechanical signals in ear (hearing)
footplate of stapes vibrates oval window
creates pressure waves in the perilymph of cochlea
transmitted to the endolymph in the cochlear duct
basilar membrane vibrates causing hair cells on the organ of corti to move against the tectorial membrane stimulating depolarisation
stimulation of CN8
from when can a foetus hear in utero
18 weeks
from when can a foetus respond to sound/voice in utero
26 weeks
what stimulates hair cells in the membranous labyrinth of the inner ear
the movement of endolymph
what senses head position
utricle and saccule
what is the sense organs of the utricle and saccule
macula
position of macula in utricle and saccule and how it relates to function
90 degrees to each other so they can respond to positions in different planes
how do the utricles and saccules work
contain otoliths which move due to gravity when the head moves
this causes sterocilia to bend initiating action potentials in the vestibular nerve fibres
what senses head movement
semi-circular canals
what are the semi-circular canals
3 ring-like extensions from the vestibule
orientation of the semi-circular canals
one in the horizontal plane and 2 in the vertical plane
what is it called where the base of a semi-circular canal meets the vestibule
ampulla
what is contained within the ampulla
crista ampullaris
what is the crista ampullaris
hair cell-containing structure which responds to rotational movement
role of the vestibulo-ocular reflex
helps maintain visual stability during head movements
what is the mechanism of vestibulo-ocular reflex
compensatory eye movements (nystagmus)
