2 Smell and Taste

Question 1

what is defined as the process which a sensory receptor is stimulated, producing nerve impulses (action potentials) that travel to the brain?

Answer 1

sensation

Question 2

what occurs when the brain interprets impulses as a visual image, a sound, taste, odor, touch, or pain?

Answer 2

sensation

Question 3

what is defined as a CNS process when the brain organizes the sensation and then begins the process of translation and interpretation

Answer 3

perception

Question 4

what occurs when the brain processes information to give meaning to it, by means of identification, meanings, emotions, memories, etc.

Answer 4

perception

Question 5

what is the preferred energy form of a receptor; its adequate stimulus

Answer 5

specific modality

Question 6

what is the minimum stimulus needed to achieve an action potential

Answer 6

stimulus threshold

Question 7

what is the physical location where sensory cells/neurons are activated

Answer 7

receptive fields

Question 8

what is the activation of sensory receptor cells and their primary, or first order neurons (except sound)

Answer 8

coding stimulus locations

Question 9

how does the brain localize sound

Answer 9

brain uses encoded APs timing/intensity differences from each ear to localize sound

Question 10

what are the number of receptors activated and the frequency, or rate of action potentials (AP) per unit timie

Answer 10

coding stimulus inttensiity

Question 11

what is the length of time that action potentials are generated, regardless of the frequency of APs

Answer 11

coding stimulus duration

Question 12

what is a 1:1 association of receptor with sensation

Answer 12

labeled line coding

Question 13

regardless of the stimulus, activating a particular ___ results in the sensation/perception that receptor’s adequate stimulus

Answer 13

labeled line

(bascially, when a particular population of neurons is active, the conscious perception is of a specific stimulus, regardless of the actual stimulus)

Question 14

do labeled lines of the senses have a specific topographic projection to the cerebrum?

Answer 14

YES

Question 15

what is a neuron(s) reduction and/or elimination of APs from neighboring neurons in a sensory neuron pathway

Answer 15

lateral inhibiition/inhibitory modulation

Question 16

what enhances contrast and makes stimulus encoding more precise?

Answer 16

lateral inhibition/inhibitory modulation

Question 17

what occurs when multiple receptors function together to encode quality, spatial, temporal characteristics of a stimulus

Answer 17

population coding

Question 18

what type of coding is limited tto any single sensory system and not limited to a single sensory modality

Answer 18

population coding

Question 19

what does the Chick-Fil-A example represent

Answer 19

population encoding of the 5 taste modalities to encode quality and hedonic value of complex tastant

Question 20

___ continue to fire as long as the stimulus is maintained.

Answer 20

tonic receptors

Question 21

___ monitor the presence and intensity of a stimulus

Answer 21

tonic receptors

Question 22

___ respond to stimulus changes; they stop responding (e.g. APs) to a sustained stimulus

Answer 22

phasic receptors

Question 23

what occurs when many sensory receptors give information (e.g. NTs) to a smaller number of neural cells? example?

Answer 23

neuronal convergence

e.g. olfactory neurons converging onto a single glomerulus

Question 24

receptor type for smell

Answer 24

chemoreceptor

Question 25

modality/ligand for smell

Answer 25

volatile, lipid soluble molecules: Esters, terpenes, aromatics, amines (remember: give me the TEAA!!!)

Question 26

embryonic origin of smell receptors

Answer 26

olfactory placode and neural crest

Question 27

what neurons regenerate?

Answer 27

Olfactory neurons No other neuron, where in PNS or CNS can regenerate

Question 28

receptor type for taste

Answer 28

chemoreceptors

Question 29

modalities/ligand for taste

Answer 29

water soluble molecules: 1. sweet - sucrose, aspartame 2. umami - glutamate 3. bitter - quinine, phenylthiorea 4. sour - H+ 5. salty - Na+

Question 30

how do the taste receptors detect SWEETNESS

Answer 30

sucrose, aspartame

Question 31

how do the taste receptors detect UMAMI

Answer 31

glutamate

Question 32

how do the taste receptors detect BITTERNESS

Answer 32

quinine, phenylthiourea

Question 33

how do the taste receptors detect SOURNESS

Answer 33

H+

Question 34

how do the taste receptors detect SALTY

Answer 34

Na+

Question 35

what is the embryonic origin for taste receptors

Answer 35

neuroepithelial

Question 36

what neuron constantly regenerates due to short life but only if innervation to the neuron is maintained

Answer 36

taste receptors - the axons regeneratet

Question 37

olfactory signal transduction cascade

Answer 37

1. odor molecules bind to GPCR 2. starts a signal transduction cascade that activates G-alpha protein (G olf), increasing adenylate cyclase activity and cAMP concentrations 3. Cyclic Nucleotide Gated (CNG) cation channels are opened, causing an influx of Ca+ and Na+ charge into receptor neuron 4. intracellular increase of + charge depolarizes olfactory neuron and generates APs (Ca2+ mediate Cl- eflux)

Question 38

T/F: a single olfactory neuron only expresses a single GPCR

Answer 38

TRUE

Question 39

while only 1/500 expresses a single GPCR, what happens to the other 499?

Answer 39

the other are repressed (chromatin remodeling) epigenetic changes)

Question 40

all olfactory neurons that express the same GPCR will send axons where? this is an example of what?

Answer 40

to the same glomerulus in the olfactory bulb e.g. of labeled line coding

Question 41

what are the basic molecular, anatomical, developmental and functional unit for odor mapping and odor processing

Answer 41

glomeruli of the olfactory bulb

Question 42

what helps create odor maps of encoded olfactory stimulation to account for discrimination of an estimated 1 trillion distinct odors in human olfaction

Answer 42

INHIBITOR MODULATION (e.g. lateral inhibition) in olfatory bulb AND population coding of individual LABELED LINES

Question 43

taste buds contain what types of cells

Answer 43

Type I, II, and III taste cells

Question 44

type II cell signal

Answer 44

1. GPCR and G-alpha protein called GUSDUCIN for signal transduction 2. different Na channel (compared to smell) activated by increased Ca2+ (Phospholipase c PLC and inositol triphosphate IP3) 3. increased intracellular Ca2+ and cell depolarization activate GAP JUNCTION HEMICHANNELS allowing ATP to move out the cell (non-selective cation channel) 4. ATP acts as a NT to generate APs in taste neuron

Question 45

When ATP acts as a NT to generate AP in taste neurons, what type of signaling is this?

Answer 45

purinergic signaling (Type II taste cells)

Question 46

what cell uses a different transduction mechanisms and synapses directly with taste neurons to generate action potentials? this is an example of what?

Answer 46

Type III taste cells - serotonergic signaling

Question 47

taste info encoded in the AP of gustatory neurons include:

Answer 47

intensity, quality, hedonic value, and behavior

Question 48

there is strong support for ___ of taste quality and behavior in less cerebral animals, despite the fact that neurophysiologic recordings of taste neurons (APs) support population coding of tastant stimuli

Answer 48

labeled line coding

Question 49

how many olfactory nerve cell receptor proteins

Answer 49

~1000 GPCRs

Question 50

what is the effect on cell receptor potential of olfactory nerve cells

Answer 50

depolarization

Question 51

what is the effect on cell receptor potential of taste receptor cells

Answer 51

depolarization

Question 52

what is the NT effect of olfactory nerve cells

Answer 52

INCREASE glutamate

Question 53

what is the NT effect of taste receptor cells

Answer 53

INCREASE ATP INCREASE SEROTONIN

Question 54

ascending CNS pathway for smell

Answer 54

CN I -> olfactory bulb -> olfactory cortex -> (parallel) thalamus and limbic system (hypothalamus, hippocampus, amygdala)

Question 55

ascending CNS pathway for taste

Answer 55

CN VII, IX, and X -> medulla (thru solitary tract nucleus) -> thalamus -> (parallel) gustatory cortex and limbic system

Question 56

when the CNS pathways for smell and taste relay to the limbic system, sensory inputs are relayed to motor outputs in the form of what?

Answer 56

reflex arcs (e.g. salivary reflex)