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A Physiology > 9. Ion channels and action potential > Flashcards

9. Ion channels and action potential Flashcards

1
Q

4 characteristics of electrotonic potential (alteration)

A
  • can be graded
  • it can be either depolarizing or hyperpolarizing
  • it decays with time (: time costant)
  • decays in space, it is localized (: space constant)
    (non-propagating, non-selfgenerating)
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2
Q

Can electrotonic potential be depolarizing or hyperpolarizing?

A

Yes, they can be both

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3
Q

Can electrotonic potential be decayed with time?

A

Yes

Electrotonic potential also has time constant

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4
Q

Can electrotonic potential decay in space?

A

Yes, it can decay in space

There is also space constant

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5
Q

Is electrotonic potential localized?

A

Yes, it can be

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6
Q

Resting condition will give resting membrane potential
-> True or false?

A

True

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7
Q

Evoking electrotonic potential

What happen to electrotonic potential when introducing positive charges?

A

Depolarization

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8
Q

Evoking electrotonic potential

What happen to electrotonic potential when introducing more and more positive charges?

A

Stronger Depolarization

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9
Q

What happen to membrane potential when introducing negative charges?

A

Hyperpolarization

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10
Q

What happen to membrane potential when introducing negative charges?

A

Hyperpolarization

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11
Q

The membrane potential is in resting condition
-> There is an inward current
-> What will happen?

A

Depolarization

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12
Q

What happen to membrane potential if the current injection stops? Why?

A

The membrane potential will return to the resting value
-> B/c the electrotonic potential decays with time

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13
Q

Give 1 sentence to describe it

A

Electrotonic potential propagates but decays in space

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14
Q

What will happen to membrane potential in case there is space constant?

A

Membrane potential reduces to its 1/e fraction

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15
Q

How is a depolarizing electrotonic potential generated physiologically?

A
  1. Opening of ligand gated, or mechanosensitive (non-specific) cation channels.
  2. Closing of leak K+ channels
  3. Elevation of EC [K+]
  4. propagation of the electrical signal from one cell to the other
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16
Q

How is a depolarizing electrotonic potential generated physiologically?

1.Opening of ___ (can be 1 of 2 types of channels)

A

ligand gated, or mechanosensitive (non-specific) cation channels.

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17
Q

How is a depolarizing electrotonic potential generated physiologically?
1. Opening of ligand gated, or mechanosensitive (non-specific) cation channels.
2. Closing of ___

A

leak K+ channels

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18
Q

How is a depolarizing electrotonic potential generated physiologically?
1. Opening of ligand gated, or mechanosensitive (non-specific) cation channels.
2. Closing of leak K+ channels
3. Elevation of ____

A

EC [K+]

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19
Q

How is a depolarizing electrotonic potential generated physiologically?
1. Opening of ligand gated, or mechanosensitive (non-specific) cation channels.
2. Closing of leak K+ channels
3. Elevation of EC [K+]
4. Propagation of the ____ from one cell to the other

A

electrical signal

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20
Q

3 examples of the depolarizing electrotonic potential

A
  1. Excitatory receptor potential
  2. Excitatory postsynaptic potential (EPSP)
  3. Junction potential (neuromuscular junction)
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21
Q

How is the hyperpolarizing electrotonic potential generated physiologically?

A
  1. Opening of K+ channels
  2. Opening of ligand gated, chloride channels (glycin, GABA)
22
Q

Consequences of Cl- channel opening

What happen to electrotonic potential if there is an inward Cl- driving force?

A

There is a decrease in electrotonic potential
-> Hyperpolarization = IPSP (inhibitory postsynaptic potential)

23
Q

When there is Cl- channel open
-> What happen to electrotonic potential if there is no driving force?

A
  • No driving force mean there is no change in electrotonic potential
  • Electrotonic potential will not change

=> The development/generation of an excitatory postsynaptic potential (EPSP) is inhibited

24
Q

How does Cl- channel opening prevent/reduce EPSP if Cl- is in electrical equilibrium under resting conditions?

A

1/ At rest (-80 mV) Cl- is in equilibrium

2/ Depolarization (EPSP) is induced by K+ channel closing -> -75 mV

3/ At this depolarized condition Cl- is no more in equilibrium: Cl- flows into the cell and counteracts further depolarization
(the higher the Cl- conductance the more efficient is the inhibition of the depolarization/excitation)

25
How does Cl- channel opening prevent/reduce EPSP if Cl- is in electrical equilibrium under resting conditions? 1/ At rest (number?) Cl- is in ___
* -80 mV * equilibrium
26
How does Cl- channel opening prevent/reduce EPSP if Cl- is in electrical equilibrium under resting conditions? 1/ At rest (-80 mV) Cl- is in equilibrium 2/ Depolarization (EPSP) is induced by ___ -> (number?)
* K+ channel closing * -75 mV
27
How does Cl- channel opening prevent/reduce EPSP if Cl- is in electrical equilibrium under resting conditions? 1/ At rest (-80 mV) Cl- is in equilibrium 2/ Depolarization (EPSP) is induced by K+ channel closing -> -75 mV 3/ At this depolarized condition Cl- is no more in equilibrium. -> WHY?
Cl- flows into the cell and counteracts further depolarization (the higher the Cl- conductance the more efficient is the inhibition of the depolarization/excitation)
28
How does Cl- channel opening prevent/reduce EPSP if Cl- is in electrical equilibrium under resting conditions? -> the higher the Cl- conductance the more efficient is the ___
inhibition of the depolarization/excitation
29
For the generation of an action potential -> Channels are indispensible with ___ (2 characteristics)
1/ is activated by depolarization 2/ the current through this channel depolarizes further
30
# Action potential (AP) In order to initiate an AP electrotonic depolarization is necessary to reach: the ___ of voltage dependent (usually) Na+ or (in some tissues) voltage dependent Ca2+ channels.
threshold potential
31
# Action potential (AP) In order to initiate an AP electrotonic depolarization is necessary to reach: the threshold potential of __ or ___
voltage dependent (usually) Na+ or (in some tissues) voltage dependent Ca2+ channels.
32
In order to initiate an AP electrotonic depolarization is necessary to reach the threshold potential of voltage dependent (usually) Na+ or (in some tissues) voltage dependent Ca2+ channels. -> This results in a series of ____
activation (and then inactivation) of voltage dependent channels
33
The membrane potential change is charecteristic “all or none” response ->True or false?
True | The membrane potential change is charecteristic “all or none” response f
34
Cells which are capable of AP production are called ___
“excitable”
35
Draw an AP graph
36
Series of events during a typical action potential
37
Conductance changes during the action potential -> Fill in the gap
38
Alterations of the excitabiliy during the AP. -> Fill in the gap
39
Alterations of the excitabiliy during the AP. -> Identify green and yellow parts
40
Alterations of the excitabiliy during the AP. -> identify
41
Identify this action potential (AP) shape?
Neurons, skeletal muscle
42
Identify this action potential (AP) shape?
Cardiac pacemaker tissue
43
Identify this action potential (AP) shape?
Cardiac muscle
44
AP of Neurons, skeletal muscle -> What is happening here?
- Local potential change - Graded potential
45
Neurons, skeletal muscle AP -> What is happening here?
**Depolarization** -> Opening of voltage gated Na+ channel
46
Neurons, skeletal muscle AP -> What is happening here?
Repolarization -> closure of Na+ and opening of K+, voltage gated channels
47
Neurons, skeletal muscle AP -> What is happening here?
Hyperpolarization -> Voltage gated K+ channels remain open after the potential reaches resting level
48
Neurons, skeletal muscle AP -> What is happening here?
1. Resting membrane potential (RMP) 2. Threshold level
49
AP shape of cardiac pacemaker tissue
50
This is AP shape of Cardiac muscle -> Identify the parts
51
Characteristic of The conduction of the action potential in a myelinized axon?
It is „saltatoric” (jumps from one Ranvier node to the next) and it’s speed can reach 100-120 m/s)
52
Compare the space constant between thin axon and large axon
Large axon has a larger space constant

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