Action Potentials - Lecture 6 Flashcards

(46 cards)

1
Q

What is the typical resting membrane potential of a cell?

A

-70mV

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

What is depolarisation?

A

Depolarization – the membrane potential becomes less negative (or even positive)

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

What is hyperpolarisation?

A

Hyperpolarization – the membrane potential becomes more negative

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

What is influx?

A

The direction of the movement of the ion into the cell

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

What is efflux?

A

The direction of the movement of the ion out of the cell

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

How does movement of ions occur?

A

Movement of ions across membranes requires ion channels

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

The movement of a positive ion into the cell causes what to the membrane potential?

A

This causes depolarisation of the cell

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

The movement of a negative ion into a cell causes what to the membrane potential?

A

This causes hyperpolarisation

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

What is passive movement of an ion through an ion channel driven by?

A

Driven by an electrochemical gradient

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

What is the movement of Na+ in response to the opening of cell membrane sodium-selective channels called?

A

Na+ Conductance

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

How can the “driving force” of an ion into/out of a cell be calculated?

A

Driving force = Membrane potential - Equilibrium potential

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

What is the definition of the “driving force” of an ion?

A

It is the energy from the concentration gradient of that ion and the energy from the electrical gradient of that ion

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

What are ion channels?

A

Ion channels are protein complexes that span the lipid bilayer to form a central pathway that allows rapid flow of selected ions

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

What are the types of ions channels that are open gated?

A

Membrane voltage – voltage-gated ion channels
Chemical substances – ligand-gated ion channels
Physical stimuli – e.g., mechanical, thermal

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

What voltage activate channels are responsible for depolarising?

A

Na+

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

What voltage activate channels are responsible for hyperpolarising?

A

K+

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

What is an action potential?

A

A brief change were the membrane changes polarity

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

Describe an action potential.

A

Sodium channels open causing sodium to enter and cause an extreme depolarising signal - This is called the upstroke

This causes voltage activated potassium to open and for potassium to leave - This is the downstroke

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

What occurs after the downstroke in an action potential?

A

An Undershoot

20
Q

What causes an undershoot in an action potential?

A

Caused by Potassium channels remaining open and Potassium continuing to leave the cell

21
Q

What occurs at the peak of an action potential?

A

It transiently changes polarity

22
Q

What triggers an action potential?

A

A depolarising stimulus

23
Q

How long does an action potential last for?

24
Q

Describe how the action potential moves along the axon?

A

Constant Velocity

Constant Magnitude

25
What must be overcome for an action potential to be sent?
A Threshold
26
What is the stimulus that will not send an action potential?
Subthreshold depolarizing stimulus
27
What is the stimulus that will send an action potential?
Threshold depolarizing stimulus
28
Describe ion conductance at the rest, before the action potential is sent.
At rest there is Potassium Conductance out of the cell
29
Describe ion conductance at the peak of the action potential.
Sodium channels open - causing depolarisation
30
Describe ion conductance at the undershoot of the action potential.
Increased Potassium conductance out of the cell
31
The activation of Sodium channels can be defined as what type of feedback system?
A Positive Feedback system - Depolarisation as sodium enters, causes more Na+ channels to open
32
The activation of Potassium channels can be defined as what type of feedback system?
A Negative Feedback System -Depolarisation cases the Potassium channels to open. Outward flow causes re polarisation, which shuts off Potassium channels
33
What turns off the Sodium Selective Ion Channels?
Opening of Potassium Channels - Re polarisation
34
There are two gates on ion channels - What are they?
The Activation Gate | The Inactivation Gate
35
Describe the gates when an ion channel is closed?
The Activation Gate is closed | The Inactivation Gate is closed
36
Describe the gates when an ion channel is depolarised?
The Activation Gate is Open | The Inactivation Gate is Open
37
Describe the gates when an ion channel is re polarising?
The Activation Gate is Open | The Inactivation Gate is Closed
38
What is the period of time when the neurone cannot transmit a signal called?
The Refractory period
39
What are the two types of Refractory Periods?
Absolutely Refractory Period Relative Refractory Period
40
Can an action potential occur in a refractory period?
Yes. Required a larger depolarisation however.
41
What is an Absolute Refractory Period?
No stimulus can elicit an action potential
42
What is a Relative Refractory Period?
A stronger than normal signal can elicit an action potential
43
What cells are used in the peripheral nervous system to insulate the axon?
Schwann Cells
44
What cells are used in the central nervous system to insulate the Axon?
Oligodendrocytes
45
Describe Saltatory Conduction in Myelinated Axons?
The Action Potential jumps from one node of ranvier to the next
46
What conducts better: | A Myelinated Axon or a Unmyelinated axon?
Myelinated