Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Human Physiology > Action Potentials, Interneuronal Communication, Week 3 Lab > Flashcards

Action Potentials, Interneuronal Communication, Week 3 Lab Flashcards

1
Q

Explain how a receptor potential in a sensory neuron can lead to the initiation of an action potential at the trigger zone of the sensory axon

A
  1. Opening transduction channels in the membrane of sensory receptors from stimuli
  2. Graded potentials generated to reach threshold.
  3. Voltage gated Na+ channels open, Na+ flows inward, and depolarizes the membrane.
  4. Na+ channels inactivate, Voltage gated K+ channels show their effect and repolarize the membrane.
  5. K+ channels close once after hyperpolarizing the membrane
  6. Return to RMP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Transduction channels are located in

A

Sensory receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What channel mediates sensory receptor potential (graded potentials)

A

Transduction channel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The size and duration of the receptor potential in transduction channels is determined by

A

how long and how many channels are open

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Voltage gated Na and K channels are located…

A

in the trigger zone and throughout the length of the axons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What channel mediates action potentials

A

Voltage gated Na and K channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The voltage gated Na and K channels open when

A

the membrane potential is depolarized to -55 mV from rest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Voltage Na channels open __, then VG K channels open more __

A

first (faster), slowly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Compare and contrast VG Na and K channels…

A
  • VG Na channels open and cause depolarization, and inactivate.
  • VG K channels open and cause repolarization and hyperpolarization (don’t inactivate)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

VG Na channels are what kind of feedback

A

positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

VG K channels are what kind of feedback

A

negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

VG Na channels stop because

A

inactivation stops depolarization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do VG K channels close

A

by repolarizing membrane potential and removing the stimulus that opens them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

all voltage gated channels are closed, membrane at resting membrane potential

A

resting state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

when membrane potential reaches threshold (graded potential), Na channel gates opens, Na ions flow in and cause a positive charge buildup (depolarization).

A

Depolarizing phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Repolarizing phase begins when

A

Na+ channel inactivation gates close and K channels open; membrane becomes repolarized once K+ ions leave the neuron and negative charges are left behind

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The hyperpolarizing phase begins when

A

as more K+ ions leave the neuron the more negative charges build up in the membrane and hyper-polarizes; K+ channels eventually close and resting membrane potential is restored

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

During the resting membrane potential, what channels are active

A

only leak channels will then open and close.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

refers to the passive process, also known as graded potential–but is localized in that trigger zone, initiating the action potential

A

Local Current Flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Local current flow is decremental due to the

A

loss of ions across a membrane through leak channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The propagation of action potential is a __ process

A

active

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

During the propagation of action potential, depolarization causes…

A

VG Na+ and K+ channels to open and local current flow to initiate more voltage gated channels to open at the next Node of Ranvier.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

In myelinated axons, leak channels are…

A

insulated by myelin–leads to loss of current flow and bette conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

In myelinated axons, Ion channels are only located at the

A

Nodes of Ranvier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Myelinated axons have what conduction

A

saltatory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The conduction in myelinated axons moves way __ than unmyelinated axons because…

A

faster, due to insulation of myelin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

In an unmyelinated axon, ion channels are…

A

placed all along the axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Unmyelinated axons have what kind of conduction

A

continuous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Unmyelinated axons take a __ time sending signals down the axon

A

longer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Describe how stimulus intensity is encoded by neurons

A

The greater the stimulus strength above threshold, the greater the frequency of action potentials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Frequency refers to…

A

how many and how long

32
Q

Explain how an increase in extracellular K+ concentration can have a dramatic effect on the Equilibrium potential for K, the resting membrane potential, and the neural status of a person.

A
  • The equilibrium potential and resting membrane potential would depolarize
  • The neural status of a person would be less likely to repolarize and stuck in a depolarized state.
33
Q

Define threshold

A

Minimum amount of stimulus required to initiate an action potential

34
Q

The time during which a cell is absolutely unable to fire another action potential

A

Absolute refractory period

35
Q

The time after an action potential when a larger stimulus is required to generate a second action potential, second stimulus can only evoke an action potential if this stimulus is relatively strong

A

relative refractory period

36
Q

Describe chemical neurotransmission, listing in correct temporal sequence events beginning with the arrival of an action potential at the pre-synaptic axon terminal and ending with a graded potential generated at the postsynaptic membrane

A
  • Action potential from VG Na+ and K+ channels arrive at axon terminal, causing a depolarization that opens up the VG Ca2+ channels.
  • Calcium in the ECF, enters the inside of the cell
  • Calcium acts with proteins in the axon terminals that help neurotransmitters dock/diffuse at the presynaptic membrane.
  • Vesicles of neurotransmitters fuse through exocytosis
  • Neurotransmitters are released into the synaptic cleft
  • Neurotransmitters diffuse across the gradient, and bind to ligand gated channels in post synaptic membrane
  • The ligand gated channels open and ions (Na) to come through
  • Na+ or ion moves in, and depolarize the membrane causing a graded postsynaptic potential in postsynaptic cell
  • Local current flow moves current through the cell body
37
Q

Explain the mechanism by which the opening and closing of ligand-gated ion channels (i.e. ionotropic receptors) is regulated

A

Neurotransmitters binding to ligand gated ion channels, open the channel

Neurotransmitters unbind= channel closes

38
Q

What’s an EPSP?

A

EPSP (Excitatory postsynaptic potential): neurotransmitters bind to the channel, channel opens, causing a depolarization

39
Q

Example of EPSP

A

ligand gated cation channel, nic. acetylcholine receptor

40
Q

What’s an IPSP?

A

IPSP (inhibitory postsynaptic potential): neurotransmitter (such as GABA) opens the channel, causing a hyperpolarization

41
Q

Example of IPSP

A

If K+ channels are open, ligand gated Cl- channel, GABA

42
Q

Explain why postsynaptic potentials are transient (i.e. short lived). In other words, what terminates the action of the neurotransmitter on the postsynaptic cell

A

They can be broken down, reused, or diffused from synaptic cleft

43
Q

occurs when two subthreshold potentials arrive at trigger zone within short period of time, sum and initiate action potential (same synapse)

A

temporal summation

44
Q

occurs when currents from nearby simultaneous graded potentials combine (separate synapses)

A

spatial summation

45
Q

In temporal summation, fired from…

A

the same presynaptic neuron at different locations

46
Q

In spatial summation, fired from…

A

different presynaptic neurons that sum potentials together to meet threshold

47
Q

Allows for two subthreshold graded potentials from the same neuron to be summed up and -55 mV (Threshold required for action potential)

A

temporal summation

48
Q

Explain two ways that activation of a G protein-coupled receptor (GPCR) can regulate opening and closing of ion channels on a postsynaptic membrane.

A
  1. Direct= the receptor that binds a neurotransmitter (NTX) is the same protein that forms the channel. (or bind to protein that works on channel)
  2. Indirect= the receptor for the neurotransmitter is a separated protein (have secondary messenger)
49
Q

Example of a direct way GPCR can open and close channel

A

Acetylcholine binds to a receptor with a G protein, G protein interacts with K+ channel, K+ channel opens, K+ leaves cell causing an IPSP, acetylcholine releases (lets go) of K+ channel, the channel closes.

50
Q

Example of a indirect way GPCR can open and close channel

A

Neurotransmitter binds to a GPCR, activates the G protein, G protein turns on enzyme, produce a second messenger, second messenger binds to ion channel and open up, ions will come in or come out.

51
Q

4 attributes of a stimulus that the CNS can distinguish:

A

Modality, location, intensity, duration

52
Q

type of stimulus in transduction channels

A

Modality

53
Q

what determines modality

A

type of stimulus in transduction channels, structure within which the channels located, and location of receptor in the tissue

54
Q

Types of modality

A

Vibration, Temperature, Pain

55
Q

nociceptors have transduction channels that open when exposed to

A

extreme temperature, intense mechanical stimuli, and chemicals released from damaged cells

56
Q

Vibration (pacinian corpuscle), temperture (thermoreceptors), and pain (chemical) are encapsulated or free nerve endings

A

Vibration= encap
Temp and pain= free nerve endings

57
Q

The location of a stimulus refers to

A

sensory neurons with separate receptive fields and sensory neurons with overlapping receptive fields

58
Q

Two factors that encode stimulus intensity

A
  1. Frequency of action potentials generated in response to the stimulus
  2. Number of sensory receptors activated by a stimulus
59
Q

Duration of a stimulus refers to

A

slow or quick to adapt to stimulus

60
Q

What receptors are involved in duration of stimulus

A

tonic and phasic

61
Q

rapidly adapt to stimulus, immediate strong receptor potential that returns to rest

A

Phasic receptors

62
Q

adapt slowly to stimulus and informs about the presence and strength of stimulus (strength of stimulus doesn’t change, receptor adapting to stimulus–reduces the number of action potentials)

A

Tonic receptors

63
Q

where a stimulus must fall into for an action potential to occur

A

receptive field

64
Q

__ of receptive fields influence our spatial resolution

A

Size and density

65
Q

enhances the difference between signal strength in neighboring secondary sensory neurons, and helps define edges (boundaries) of stimulus

A

Lateral inhibition

66
Q

Lateral inhibition continues to __ the response of a stimuli in neighboring sensory neurons while __ the strength of a signal of the main sensory neuron to the cortex

A

weaken, maintaining

67
Q

affects the release of neurotransmitters

A

Presynaptic inhibition

68
Q

affects the events at the receptors

A

Post synaptic inhibition

69
Q

Differentiate between sensory receptor activation and perception of a stimulus.

A

We are only aware of a stimulus if it reaches threshold

70
Q

What happens when an excitatory postsynaptic potential occurs on a dendrite?
A. positive ions move via local current flow from the postsynaptic site to more negative regions within the cell.
B. ligand-gated K channels open to repolarize the membrane potential.
C. the membrane potential is hyperpolarized and the neuron is less likely to generate an action potential.

A

A

71
Q

What happens when two or more synapses on a single postsynaptic neuron are activated at the same time?

A

spatial summation

72
Q

Why can’t an action potential be generated, no matter how large the stimulus, during the absolute refractory period?

A

Because too few voltage-gated Na channels have recovered from inactivation.

73
Q

Why is the conduction velocity of action potentials faster in myelinated axons than in unmyelinated axons?
A. Because the distance between adjacent nodes of Ranvier is larger than the distance between adjacent clusters of voltage-gated Na and K channels on unmyelinated axons.
B. Because voltage-gated Na channels open faster on myelinated axons than on unmyelinated axons
C. Because myelinated axons have a smaller diameter than unmyelinated axons

A

A

74
Q

myelinated axons have a __ diameter than unmyelinated axons

A

larger

75
Q

In which one of the following ways do primary sensory neurons differ from multipolar neurons?
A. Action potentials are initiated at the peripheral end of the axon in primary sensory neurons.
B. Action potentials are initiated by the summation of postsynaptic potentials on the soma of primary sensory neurons.
C. Action potentials are propagated along the axon by regeneration of action potentials at regular intervals in primary sensory neurons.

A

A

76
Q

When an action potential arrives at the presynaptic axon terminal it triggers neurotransmitter release into the synaptic cleft. What causes neurotransmitter release to stop?

A

Ca2+ concentration in axon terminal is decreased

Human Physiology (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions