Taste, Smell, Auditory- Edwards Flashcards
explain the mechanisms by which olfactory and taste receptors are activated
chemicals activate these receptors, which contain vesicles in their neurons that regulate the synapse at the level of the receptor
are taste receptor cells neurons?
nope but they do release neurotransmitter that must synapse with neurons farther up the pathway
can an individual taste receptor cell respond to multiple tastes? is this efficient?
yes, but responding to one taste is best
what is a unique feature about olfactory neurons?
they can regenerate!!
how do olfactory pathways project into the telencephalon? how does this compare to conscious recognition of odor?
project into telencephalon without a thalamic relay (faster response); however for conscious recognition of odor, there is a relay through the thalamus to the neocortex 9 (takes longer)
diagram the neural pathways conducting taste and olfaction into the central nervous system
taste: project into the CNS via the nucleus of the solitary tract
CN 7, 9, 10 innervate the tongue and receive neurotransmitter from chemicals; taste goes first to the medulla for unconscious recognition, then to the pons, where part goes to the thalamus to relay the signal to the neocortex for conscious perception of what was eaten; another part of the signal goes to the hypothalamus/accumbens (limbic system) to be happy about eating
CN 5 somatically perceives the feel of food
where do the neural pathways conducting taste and olfaction interact peripherally and within the central nervous system?
olfaction: olfactory bulb projects into telencephalon and first reaches the amygdala, piriform lobe, other parts of the limbic system, then relays through the thalamus to the orbitofrontal neocortex (conscious recognition)
predict behaviors elicited by noxious odors as well as pleasant odors and why these might evoke such powerful memories
the olfactory information goes first (vie the olfactory tubercle which projects into the brain) to the hypothalamus and amygdala (limbic system) which can trigger memories as a protection mechanism (smoke = danger)
identify the gross components of the auditory system
pinna: shell of ear
vertical canal lead to ear canal leads to horizontal canal which meets the tympanic membrane
explain the function of bony ossicles
transmit sound from outer ear to inner ear (from air to fluid)
describe the structure of the inner ear and indicate where the organ of Corti is found
3 bony ossicles:
1. semicircular canals, contain semicircular ducts and crista ampullaris
2. vestibule, contains utricle and saccule each with a macula
3. cochlea: contains organ of corti (on basilar membrane of scala media), which has scala vestibuli (continuous with vestibule; sound vibrations ascend) and scala tympani (continuation of scala vestibuli and terminates in contact with middle ear); cochlea separated from scala by scala media/cochlea duct
identify the cells found in the organ of cort
contains hair cells that are innervated by CN 8; embedded in tectorial membrane (a gelatinous tongue shaped matrix that rests on the apical surface of the hair cells), plus support cells and afferent and efferent nerve terminals
describe the process by which neural signals are generated out of the organ of corti
sound waves make hair cells brush against tectorial membrane, causing hair cells to fire, sending afferent impulses via CN 8, which innervates the cells
illustrate the projection of CN 8 into the brain; describe the auditory pathway in the brain from the cochlear nucleus to the temporal lobe of the cerebrum
CN 8 sends signals:
first to cochlear nucleus in medulla oblongata
second to caudal colliculus in pons?
third to medial geniculate nucleus in the thalamus
fourth to neocortex in cerebrum for conscious perception
predict the signs of a lesion at any point from the outer ear to the temporal lobe
from pinna to organ of corti = conduction deafness, easier to deal with
from organ or corti to brain = neural deafness
