Taste and Olfaction Flashcards
what are chemical senses?
special sensory systems that detect minute quantities of chemicals in the environment
what do ‘tastant’ molecules interact with? odorant molecules?
structures called taste buds on tongue, palate, pharynx, epiglottis and esophogus
olfactory receptor neurons on the superior conchae
what cranial nerves contribute to flavor?
CN I
CN V
CN VII
CN IX
CN X
what cortex do the CNs send stimuli to in order to stimulate the idea of flavor?
orbitofrontal cortex
what are the landmarks of the tongue?
sulcus terminalis which divides anterior from posterior
median sulcus which divides the tongue at the midline
what are papillae?
sensory structure on the tongue that either contain taste buds or manipulate food
what are the three important papillae?
filiform - contains no taste buds and important for food manipulation
fungiform- mushroom shaped and contain taste buds
circumvallate- concentrated near sulcus terminalis and contain many taste buds
what three cells do taste buds contain?
- taste receptor cells
- sustentacular cells: provide nutrition and support
- basal stem cells: replace damaged TRCs
what are glands of Von Ebner?
minor salivary glands that provide moisture and contain enzymes that help digest food
from the anterior 2/3 of the tongue, taste fibers travel in which nerve?
lingual nerve that contains facial nerve fibers (CN VII) and trigeminal nerve fibers (CN V)
from the posterior 1/3 of the tongue, taste fibers travel in what nerve?
glossopharyngeal nerve (CN IX)
from the epiglottis, pharynx and palate, taste fibers travel in what nerve?
CN X
which ganglion is associated with facial nerve (CN VII)?
geniculate ganglion
which ganglion is associated with glossopheryngeal nerve (CN IX)?
petrosal ganglion
which ganglion is associated with vagus nerve (CN X)?
nodose ganglion
where do the central processes of all primary taste afferents enter and terminate and what do they form?
medulla
nucleus of solitary tract
solitary tract
axons of neurons in the nucleus of the solitary tracts ascend and project bilaterally where?
- ventral posteromedial nucleus of the THALAMUS
- then to the primary gustatory cortex via internal capsule
what are the substructures of the primary gustatory cortex?
- anterior region contains insula
- frontal operculum in the inferior frontal gyrus
where does the primary gustatory cortex project to inform flavor?
orbitofrontal cortex
what is dysgeusia and what are the three types?
an alteration in taste
- hypogeusia: reduced sense of taste
- ageusia: inability to taste
- aliageusia: pleasant tastes start to taste unpleasant
where do odorants enter and then contact?
- nasal cavity through the external nares and lodges
- contact dendrites of the olfactory receptor neurons of CN 1
olfactory receptor neurons sit in a cell layer that contains?
supporting cells
basal stem cells
glands
each olfactory receptor neuron (ORNs) has how many receptors?
ONE
what do ORNs synapse with and where?
mitral cells in the olfactory bulb
what is a glomerous?
a ball of mitral cell dendrites and axons of ORNs
what are olfactory striae?
mitral cell axons that project out of the olfactory bulb and split into two tracts
where do medial and lateral striae project?
medial: project to contralateral structures to aid in bilateral processing
lateral: project ipsilaterally to olfactory cortex located on the uncus of the temporal lobe
