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Animal Physiology > Ch 7. Part 1 (Book) > Flashcards

Ch 7. Part 1 (Book) Flashcards

1
Q

______ organs provide the only channels of communication from the external world to the nervous system

A

sensory organs

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2
Q

what 2 main places is sensory input gathered from and where is it processed?

A

the environment

within the body

processed by the nervous system

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3
Q

sensory reception begins in _____ containing sensory receptor cells

A

organs

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4
Q

are sensations a subjective or objective experience?

A

subjective

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5
Q

when do sensations arise

A

when signals captured by sensory receptor cells are transmitted through the ns to parts of the brain that interpret them

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6
Q

what 2 things do you have to consider when describing sensory physiology

A

the properties of the sensory receptor cells

how the ns processed the information

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7
Q

evolution of sense organs

A

from single receptor cells to organs with the cells are arranged and have accessory structures

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8
Q

what is the advantage of having sensory organs vs. single receptor cells

A

more accurate analysis of stimuli

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9
Q

what is a modality

A

a type of sensation

ex. light or tough

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10
Q

5 modalities

A

vision

touch

hearing

taste

smell

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11
Q

what is a quality?

A

the feature that characterizes stimuli within a modality

ex. red or blue light

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12
Q

what does an interoceptive receptor sense

A

responds to signals within the body

not a conscious process

ex. chemical/thermal state of the body

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13
Q

what does a proprioceptor sense

A

positions of muscles and joints

type of interoceptive receptor

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14
Q

where does sensation begin

A

the part of the membrane of sensory receptor cells that is specialized for reception

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15
Q

what is the important feature of any stimulus

A

ability to modify the conformation of the receptor cell

requires energy

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16
Q

are some sensory receptor cells neurons?

A

yes

ex. vertebrate photoreceptors and touch receptors

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17
Q

are some sensory receptor cells epithelial cells?

A

yes

ex. taste receptors and hair cells in the vertebrate inner ear

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18
Q

2 pathways a receptor cell sends a signal to the CNS

A

depolarizing receptor potential –> spike-initiating zone –> APs

release of neurotransmitter resulting from a depolarizing or hyperpolarizing potential

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19
Q

2 different types of cells that use APs to transmit signal

A

invertebrate sensory neurons have soma far away from CNS

vertebrate sensory neurons have the soma close to the CNS

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20
Q

receptor cell that transmits signals using nt

A

receptor cell forms a chemical synapse with a neuron

a depolarizing/hyperpolarizing curent spreads to the presynaptic region and releases nt

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21
Q

primary afferent neuron

A

the neuron whose axon carries the signal to the CNS

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22
Q

2 general features of a sensory receptor cell

A

they are highly selective for a specific kind of energy

the reason for this modality selectivity is that the receptor is specialized to amplify that type of signal

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23
Q

transduction

A

process of a receptor cells turning stimulus energy into the energy of a nerve impulse

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24
Q

rhodopsin is a visual _____ that contains the protein _____, coupled to the light-absorbing molecule _______

A

pigment, opsin, retinal

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25
Q

general pathway of signal transduction

A

receptor cell is stimulated –> conformational change in receptor –> amplification of signal –> alteration of ion channels (opening or closing)

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26
Q

each sensory receptor cell _______ a specific form of stimulus into a membrane current that changes the ________ _______ of the receptor cell

A

transduces, membrane potential (Vm) of the receptor cell

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27
Q

3 basic events of a receptor cell

A

detection of a sensory stimulus

amplification of the stimulus

encoding the stimulus into electrical signals

28
Q

threshold of detection

A

the weakest stimulus that produces a response in a receptor cell 50% of the time

29
Q

why is the response time of a receptor cell important?

A

so it can convey information about rapidly changing stimuli accurately

30
Q

receptor proteins have a common structure

A

7 transmembrane a-helices

associated with a G-protein

31
Q

what typically amplifies the sensory signal

A

an enzyme cascade

32
Q

does detection of all sensory modalities use G-proteins

A

no, some like salt and sour tastes just use ion channels

salt Na+

sour K+

33
Q

can a single receptor cell report the quality of the stimulus

A

no, this requires patterns of activity in many receptor cells

ex. a single photoceptor cannot tell if light is red or blue

34
Q

many mechanisms involving sensory adaptation involve what ion

A

Ca2+

35
Q

what does a stretch receptor sense

A

muscle length

ex. abdomen of crayfish

36
Q

experiment involving stretch receptors in crayfish

A

microelectrode inserted into soma to detect APs

found frequency of APs depended on strength of stretch

37
Q

experiment to find what the source of the APs from stretch receptors in crayfish

A

small stretch –> small depolarization (receptor potential)

larger stretch –> larger depolarization

found stretch caused pos ions to flow into the cell to depolarize

38
Q

what does TTX do

A

blocks voltage-gated Na+ channels, which blocks APs but not receptor potentials

ex. in stretch receptors for crayfish

39
Q

phasic receptors

A

produces APs only during one part of stimulation, usually the beginning or ending or both

can’t convey info about duration of stimulus

40
Q

tonic receptors

A

fire APs for the duration of stimulus

can convey info about the duration of stimulus

41
Q

is receptor current regenerative?

A

no - spreads through the cell electrotonically (decrementally)

42
Q

is receptor current and receptor potential graded?

A

yes

43
Q

generator potential

A

when a receptor potential spreads to the spike-initiating zone and affects AP generation

44
Q

dynamic range of a receptor cell or organ

A

encoding stimuli over a limited range of intensity

below the range the receptor doesn’t respond

above the range the response is saturated

45
Q

3 factors that set the maximum response a receptor can produce to a strong stimulus

A

finite # of ion channels –> upper limit of current flow

upper limit of amplitude of receptor pot b/c it cannot exceed the reversal pot of the receptor current

upper limit of AP frequency b/c refractory period sets time before another AP is sent

46
Q

within the dynamic range, the amplitude of the recptor potential is proportional to the _______ of the stimulus intensity

A

logarithm

this is maintained when the signal reaches the CNS

47
Q

why can sense organs function over large dynamic ranges

A

tranduction has a broad dynamic range

sensory adaptation

neuronal networks can extend the dynamic range of the system past the abilities of single receptor cells

48
Q

equation for how change in stimulus intensity affects amplitude of receptor potential

A

delta I / I = K

I = stimulus intensity

K = constant

49
Q

recruitment

A

when an increasingly powerful stimulus triggers more and more receptors that are less sensitive

50
Q

range fractionation

A

single receptors only cover a portion of the dynamic range

51
Q

example of range fractionation

A

vertebrate eye

rods are more sensitive to light and respond to dimmer stimuli

cones respond to bright light that would saturate the rods

52
Q

sensory adaptation

A

changes of percieved intensity when the intensity of the physical stimulus has not changed

53
Q

do tonic receptors exhibit sensory adaptation?

A

not really, they fire APs continuously

54
Q

do phasic receptors exhibit sensory adaptation

A

yes, they adapt quickly

sometimes they only generate APs when the stimulus intensity is changing

55
Q

sensory adaptation in mechanoreceptors

A

the receptor or accessory structures filter info from transient stimuli

56
Q

sensory adaptation cause in photoreceptors

A

the visual pigment gets bleached and must be metabolically regenerated before it responds again

57
Q

sensory adaptation enzyme cascade

A

may be inhibited by an intermediate or buildup of product

58
Q

sensory adaptation electrical properties

A

activation of receptors may diminish b/c buildup of Ca in the cell goes up during stim

activates Ca-dependent K channels that shifts Vm toward resting potential

59
Q

sensory adaptation spike-initiating zone

A

becomes less excitable during sustained stimulation

60
Q

sensory adaptation CNS

A

adaptation takes place in higher order cells in the CNS

61
Q

6 types of sensory adaptation

A

receptor/accessories filter (mechano)

receptors get run down (photo bleached)

enzyme inhibition

electrical properties change by inc Ca

spike initiation zone desensitized

higher-order cells in CNS

62
Q

ex. pacinian corpuscle sensory adaptation

A

area of sensitive receptor memb. surrounded by layers of conn tissue

layers filter out prolonged stimulus (like clothing)

only get a response at the onset and offset of stim (putting on and taking off clothing)

63
Q

in the absence of stimuli, some receptors produce ____________ APs or release nt

A

spontaneous

small increase in stimulus energy increases rate of firing or shortens intervals of APs

stimulus can also decrease frequency

64
Q

why is there modulation of the base AP firing

A

allows the receptors to be more sensitive to changes in stimuli than if they had to bring a completely inactive spike-initiating zoe to threshold

allows receptor to convey info about the polarity of stimulus (ex. if hair moved one direction freq inc, if in opp direction freq decreased.)

65
Q

efferent control of receptor sensitivity in crayfish/lobster abd stretch receptors

A

efferent axons innervate the sense organ itself

fairly constant tension on muscle so sensitivity is maintained

efferent inhibitory axons synapse the receptor cells to decrease receptor pot when active

66
Q

feedback inhibition of crustacean abd stretch receptors

A

receptor activity produces signals that inhibit the receptors themselves via efferent inhib nerves (autoinhibition)

if inhibits anterior/posterior neighbors (lateral inhibition)

67
Q

purpose of feedback inhibition of receptors

A

keeps AP freq within the max freq range set by refractory period

Animal Physiology (26 decks)

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