Lecture 14 Flashcards by Julia Boudreau

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

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graded means something __

varies in size in relation to the stimulus

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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

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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

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the duration of the stimulus is represented in the __

duration of the receptor potential, then duration of the series of action potential

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receptor /generator potential is __ at the trigger zone

integrated

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neurotransmitter release varies with the __ arriving at the axon terminal

pattern of action potentials

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strength of stimulus is encoded by __

amount of neurotransmitter released

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sensory adaptation

the process in which changes in the sensitivity of sensory neurons occur in relation to the stimulus

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olfactory pathways from the nose project to __

most sensory pathways project to __

olfactory cortex; thalamus

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the thalamus __

modifies and relays information to cortical centers

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2 types of chemical sensation

olfactory and gustatory

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our oldest and most primitive sense is __

chemical sensation

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why do we call it chemical sensation?

because the stimulus is a chemical

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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

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gustatory sense helps us detect __ and provides info about food __ (3)

ingested tastants (soluble molecules); food quality, quantity, and safety

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olfactory receptor neurons (ORNs) are found in the __

epithelial sheath/olfactory epithelium

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odorants are transduced in the __

olfactory epithelium

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the olfactory bulb receives input from __ and sends info __

olfactory epithelium; deeper into the brain/ to downstream targets

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this connects olfactory epithelium to the olfactory bulb

olfactory nerve

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olfactory processing is essential for the conscious __ and the association of __

appreciation of smells; odorants with environmental stimuli

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olfactory processing can influence your __

motor, visceral, and emotional reactions to smells

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what is humans’ least acute sense?

olfaction, animals have superior sense of smell

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we humans can reliably detect the odors of __ and __ very well

ozone; ethanol

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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?

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