Physiology of taste and smell Flashcards
what is gustation?
physiology of taste
what are the organs of taste?
taste buds
where are most of the sensory receptors for taste?
in taste buds on tongue
2 types of cell in taste bud?
receptor cells and support cells
life span of taste receptor cells
10 days
where are taste buds present?
tongue, palate, pharynx, epiglottis
which papillae have taste buds?
fungiform
foliate
vallate
which papillae doesnt have taste buds?
filiform
what happens when a taste chemical binds to a receptor?
the cell ionic channels are altered and produce a depolarising receptor potential
what does the receptor potential do?
initiate action potentials in afferent nerve fibres
what do the afferent taste fibres reach the brainstem via?
chorda tympani branch of facial nerve (anter 2/3rd tongue)
glossopharyngeal (posterior 1/3rd tongue)
vagus( areas other than tongue)
what are the 5 primary senses of taste?
salty sour sweet bitter umami
what is ageusia?
loss of taste function
can be caused by nerve damage, local inflammation and endocrine disorders
what is Hypogeusia?
reduced taste function
caused by chemo and medication
what is dysgeusia?
distortion of taste
caused by glossitis, gum infection, reflux, tooth decay, chemo URTI
what is olfaction?
physiology of smell
3 types of cell in oral mucosa?
olfactory receptor cells
supporting cells
basal cells
which cells have specialised nerve endings of renewable afferent neurones
olfactory receptor cells
what is special about each of the renewable afferernt neurones?
they have a thick short dendrite at and expanded end called an olfactory rod. and from these rods, cilia project to the surface of olfactory mucosa
life span of olfactory receptors?
2 months
what acts as precursors for new olfactory receptor cells?
basal cells
what collectively makes the olfactory nerve?
axons of many olfactory receptors
what do the axons of the olfactory receptors pierce to enter the olfactory bulbs?
cribiform plate
what do the olfactory bulbs do?
transmit smell to brain
to be smelled a substance must be..?
volatile and water soluble
what is anosmia?
inability to smell
caused by viral infection, head trauma, nasal polyp
what is hyposmia
reduced ability to smell
what might hyposmia be a an early sign of?
parkinsons
what is dysosmia?
altered sense of smell
