Brainscape's Knowledge GenomeTM

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


See full index

Neuroscience > Lecture 2: Action Potentials + Propagation Synaptic Transmission > Flashcards

Lecture 2: Action Potentials + Propagation Synaptic Transmission Flashcards

1
Q

why are neurons electrically polarized like all cells?

A

Due to an unequal distribution of ions on each side of the plasma membrane

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

are neurons electrically excitable?

A

yes unlike most cells

the membrane potential can deviate from -70m

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

what is the change in membrane potential (voltage)

A

the signal neurons use to communicate with other neurons or other targets (muscles, glands).

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

what are graded potentials (GPs)

A

changes in membrane potential are typically small, slow and gradual and either decrease (depolarize) or increase (hyperpolarize) membrane potential

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

in graded potentials, what is the activity of the neuron related to

A

the voltage at any point in time

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

what type of communication are neurons capable of only generating GPs involved in

A

local or short distance communication, as signal transmission distance is limited (typically to a few mm).

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

what are action potentials (APs)

A

changes in membrane potential are large and typically repetitive, with rapid alternating depolarization and hyperpolarization (“spikes”) of membrane potential

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

in action potentials, what is the activity of the neurons related to

A

not the voltage, but the number of action potential spikes over time

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

what type of communication are neurons that generate APs capable of

A

long-range signaling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

do all neurons that generate APs procuce GP as well?

A

yes because the generation of APs depends on the generation of GPs

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

what would happen if there were no sodium Na channels

A

the resting membrane would be more negative

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

How are graded potentials generated?

A

with GPs, the permeability of Na+ channels can change (go up or down) by neurotransmitters or mechanical forces.

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

how are action potentials generated?

A

Starting from rest (-70 mV), a stimulus first produces a graded depolarization. Then, at a certain voltage, there is a rapid, but brief, depolarization to +35 mV. The voltage drops quickly, and there is a period of calm before it happens again.

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

during stimulation of an action potential, does the membrane potential return back to -70 mV?

A

not during the period of stimulation, but at the end of the stimulation, there is a gradual hyperpolarization back to rest.

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

what makes APs special?

A

they are produced by ion channels that are “voltage-gated.”

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

why do voltage-gated Na channels drop and not keep increasing

A

they are subject to intrinsic inactivation. Soon after activation, they inactivate, causing the falling phase after the peak

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

Does sodium moving into the cell cause depolarization or repolarization

A

depolarize (move towards positive)

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

what is a refractory period and what are the two types

A

Voltage-gated Na+ channel inactivation imposes a refractory period on AP generation.

absolute refractory period

relative refractory period

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

what is an absolute refractory period

A

the period during which, no matter how strong the stimulus, another AP cannot be generated. It is due to the inactivation of voltage-gated Na+ channels.

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

what is a relative refractory period

A

the time following Na+ channel reactivation, but when voltage-gated K+ channel are still sufficiently active to oppose depolarization to threshold. However, a sufficiently strong stimulus could overcome such opposition.

21
Q

what 2 things impose limits on the frequency that action potentials can be generated

A

The refractory periods

the after hyperpolarization

22
Q

Why are graded signals limited to local or short-distance?

A

Electrical current flows passively both down the interior of the axon and leaks through the membrane. With distance, the amplitude of the potential change decreases.

23
Q

How can we make the action potential travel further?

A

active regeneration of the signal

there are two mechanisms

24
Q

what is the less ideal mechanism to regenerate the signal?

A

Cover unmyelinated axons with voltage-gated channels so that the action potential is constantly being boosted

25
Q

what are the disadvantages to Cover unmyelinated axons with voltage-gated channels

A

its slow (takes time for each segment of the axon to reach threshold)

costs a lot of energy (the extensive movement of Na+ and K+ along the axon)

26
Q

what is the ideal mechanism to regenerate the signal?

A

Insulate the axon, with myelin leaving some gaps (nodes), to decrease decay of signal.

27
Q

what happens in the gaps (nodes) of myelinated axons?

A

Voltage-gated Na+ and K+ channels are only found in the nodes. Myelin reduces the decay of the electrical signal so that the voltage is above threshold when it reaches the node. At the node the signal is regenerated.

28
Q

why are myelinated axons faster?

A

fast speed of transmission because only the voltage-gated channels within the nodes need to be activated

29
Q

how is conduction velocity affected by axon diameter?

A

larger axons have less longitudinal resistance and thicker myelin so they’re faster

30
Q

what are the 2 basic types of synapses

A

Electrical synapses (gap junctions)

Chemical synapses (release neurotransmitter)

31
Q

what are electrical synapses (gap junctions)

A

Transmembrane channels that join to connect the interior of one cell with the interior of another cell.

Bidirectional and with essentially no synaptic delay.

32
Q

what are chemical synapses?

A

neurotransmitter released at axon terminals, crosses synaptic cleft, acts on receptors on postsynaptic membrane

33
Q

is neurotransmission unidirectional or bidirectional?

A

unidirectional: presynaptic→postsynaptic.

34
Q

is there ever partial fusing of vesicles

A

no. If a vesicle fuses, all of the neurotransmitter in the vesicle is released.

35
Q

what is a quantum

A

The amount of neurotransmitter released by a single vesicle

quanta-vesicles released over time

36
Q

The total amount of neurotransmitter released by a single action potential corresponds to what?

A

the number of quanta

37
Q

what is Glutamate

A

the most common excitatory neurotransmitter in the CNS.

Vesicles are loaded with glutamate by a vesicular glutamate transporter

38
Q

what are the 2 types of post-synaptic receptors that glutamate acts as

A

AMPA receptors

NMDA receptors

39
Q

what is the duration of an excitatory post-synaptic potential produced by AMPA alone vs with AMPA and NMDA

A

Just AMPA = brief

AMPA + NMDA = longer

40
Q

what do GABA b receptors do

A

metabotropic receptors that increase efflux of K+

41
Q

What will happen if sodium ions are not allowed to leave the membrane?

A

Returning to a resting membrane potential is not possible

42
Q

The most common type of synapse are what kind

A

chemical

43
Q

What enables neurotransmitters to be released?

A

Introduction of ions

44
Q

Chemical synapses perform the following 2 functions:

A

Provide cell to cell communication

Produce secondary current in post synaptic neuron

45
Q

true or false:
The “amount of brain” devoted to a particular body part is related to tactile acuity. This would generally mean that “more brain area” is equivalent to a smaller 2 point discrimination (less distance between the two points of stimulus).

A

true

46
Q

what are Nodes of Ranvier

A

The location of ions channels

47
Q

true or false:
A neuron can use multiple neurotransmitters at each of its synapses

A

true

48
Q

what is Depolarization

A

Going from a negative resting membrane potential to a more positive charge

49
Q

Opening of K+ channels causes

A

Hyperpolarization

Neuroscience (20 decks)

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