Lecture 14 Flashcards
receptor potentials are graded in __ according to the strength of the stimulus, which is then converted into __.
intensity is represented by the __ of action potentials
amplitude; action potential frequency; frequency
graded means something __
varies in size in relation to the stimulus
it is at the __ (before the __) that the amplitude of the receptor potential is converted into action potentials (if that receptor potential _)
trigger zone; before the nodes of Ranvier; exceeds the threshold
the intensity of the stimulus is represented by the __ of action potentials, NOT the __ (they’re all the same __)
frequency; size/amplitude; same size/amplitude
the duration of the stimulus is represented in the __
duration of the receptor potential, then duration of the series of action potential
receptor /generator potential is __ at the trigger zone
integrated
neurotransmitter release varies with the __ arriving at the axon terminal
pattern of action potentials
strength of stimulus is encoded by __
amount of neurotransmitter released
sensory adaptation
the process in which changes in the sensitivity of sensory neurons occur in relation to the stimulus
olfactory pathways from the nose project to __
most sensory pathways project to __
olfactory cortex; thalamus
the thalamus __
modifies and relays information to cortical centers
2 types of chemical sensation
olfactory and gustatory
our oldest and most primitive sense is __
chemical sensation
why do we call it chemical sensation?
because the stimulus is a chemical
olfactory sense helps us detect __, (1) provides info about __ (3), and influences __ (4)
airborne molecules; self, others, and identifying food as hazardous; social interactions, reproduction, aggression, and feeding
gustatory sense helps us detect __ and provides info about food __ (3)
ingested tastants (soluble molecules); food quality, quantity, and safety
olfactory receptor neurons (ORNs) are found in the __
epithelial sheath/olfactory epithelium
odorants are transduced in the __
olfactory epithelium
the olfactory bulb receives input from __ and sends info __
olfactory epithelium; deeper into the brain/ to downstream targets
this connects olfactory epithelium to the olfactory bulb
olfactory nerve
olfactory processing is essential for the conscious __ and the association of __
appreciation of smells; odorants with environmental stimuli
olfactory processing can influence your __
motor, visceral, and emotional reactions to smells
what is humans’ least acute sense?
olfaction, animals have superior sense of smell
we humans can reliably detect the odors of __ and __ very well
ozone; ethanol
we humans can still detect many odorants. we can detect changes in __ and __
concentration; molecular structure (ex: spearmint and caraway, mirror images)
indole is an odorant that a high concentration of smells __ whereas a low concentration of smells __
putrid; floral
Bowman’s gland __
produces mucus
olfactory cilia are __
the first thing to pick up odorants and are covered in mucus
order of things:
olfactory cilia; receptor cells; receptor cell axons (olfactory nerve) to olfactory bulb
olfactory receptor neurons contain __
ciliated endings that sense chemical signals
support cells:
provide physical and trophic support for ORNs and basal cells
mucus is critical for protecting __
the sensory endings of ORNs
basal cells are a __ layer to produce __
stem cell; new ORNs
olfactory epithelium consists of __ (5)
basal cells, support cells, Bowman’s organs, mucus, ORNs
ciliated endings of ORNs are __ and have receptors that are __
exposed to the environment; activated by odorants
are receptors located anywhere else on ORNs besides the ciliated endings?
no
odorant receptors are __ receptors
G-protein coupled receptors
Gaolf activates __, producing __ which activates __ and causes influx of __ (2). influx of __ causes __ and activates __ to cause __ efflux and more __
repolarization happens through the __
adenylate cyclase; cAMP; cAMP-gated cation channels; calcium and sodium; calcium; depolarization; ca-gated Cl channels; Cl; and more depolarization
Na/Ca exchanger
like other neurons, individual ORNs are sensitive to __.
there is a higher __ to specific odors, but in general most are __ and respond to a __ variety of odorants
subsets of stimuli; affinity; broadly-tuned; large
ORNs have __ that relay odorant info directly to __
axons; the brain (the olfactory bulb)
T/F olfactory bulb is part of the brain
true
the __ of ORNs make up the olfactory nerve
axon bundles
each olfactory neuron makes __ synaptic connections to __ in the olfactory bulb
glutamatergic; mitral cells
mitral cells are the principal __
projection neurons
glomeruli = spherical accumulation of __, connections between __ and __
neuropil; ORNs and mitral cells
neuropil is anything that isnt __
the cell body (axons and dendrites)
in the glomerulus, the dendrites of __ synapse with axons of __ that express the same __
mitral cells; ORNs; single odorant receptor!
the glomerulus is the site of a crazy amount of __
convergence
are there more mitral cell dendrites or more ORN axons in the glomerulus?
ORN axons by far! (convergence)
mitral cells have a __ receptive field which means they have greater __
large; sensitivity
individual glomeruli respond to __
downstream targets are more __
specific odorants; broadly-tuned
olfactory info is distributed __
broadly!
taste cells are found in __ (4)
tongue, soft palate, pharynx, and esophagus
cranial nerve VII connects to taste cells in the __
cranial nerve IX connects to taste cells in the __
cranial nerve X connects to taste cells in the __
tongue; soft palate; epoglottis and esophagus
what nucleus of the thalamus is involved in gustatory sense?
ventral posterior medial nucleus (VPM)
taste stimuli is non-__ and __ (hydrophobic/hydrophilic)
volatile; hydrophilic
tastants are detected over full surface of the tongue via __
taste papillae
taste papillae contain __, surrounded by __ of tongue epithelium
taste buds; invagination (trenches)
taste buds contain __ (3)
taste cells, support cells, and basal cells
taste buds are innervated by __
gustatory afferent axons
taste system detects five tastants:
bitter, sour, sweet, salty, and umami (MSG/amino acid)
different regions of the tongue have different __ for various tastes
thresholds
discontinuity in taste sensitivity may be related to the __ (3) qualities detected by the taste receptors
aesthetic, metabolic, and toxic
each region/class of tastant activates different regions of the __ (information thus remains __)
insula cortex; segregated
each of the primary tastes has its own distinct __ that are expressed in subsets of taste cells
class of receptors
taste cells are __: __ domain contains taste receptors, and __ domain releases neurotransmitter (serotonin, GABA, or ATP)
polarized; apical; basal
taste receptors are either __ or __
ion channels or G-protein coupled receptors
salts and acids activate __ (ion channels or GPCRs?)
ion channels
salts activate amiloride-sensitive Na channel. when enough Na is present __
high influx causes depolarization
acids (sour) activate __, allows for influx of __ and __, causing depolarization
proton (H) -activated cation channel; H and Na
sweet and umami activate __
heterodimeric (same two parts everytime) GPCRs
T1R2 and T1R3 = __; T1R1 and T1R3 = __ (these are the two parts of their __)
sweet; umami; GPCRs
in sweet and umami: activation of G-protein leads to activation of __ which cleaves __ into IP3 and DAG, IP3 activates the IP3-gated TRP channel, causing influx of __, and depolarization
PLC; PIP2; Ca
bitter activates __
monomeric GPCRs (T2R)
bitter cascade:
same as sweet and umami
TRPM5 knock out mice are __
similarly, __ knockout mice also do this
the rescue of __ in TR2 expressing cells only rescues behavioral response to __
not responsive to any taste; PLC; PLC; bitter (Quinine)
expression of an ectotopic receptor in T1R2 cells causes mice to __
react to a synthetic molecule that is not normally attractive
the data suggest that taste cells trigger __
dedicated behavioral outputs
