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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
Q

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

1/ At rest (number?) Cl- is in ___

A
  • -80 mV
  • equilibrium
26
Q

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?)

A
  • K+ channel closing
  • -75 mV
27
Q

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?

A

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
Q

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 ___

A

inhibition of the depolarization/excitation

29
Q

For the generation of an action potential
-> Channels are indispensible with ___ (2 characteristics)

A

1/ is activated by depolarization
2/ the current through this channel depolarizes further

30
Q

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.

A

threshold potential

31
Q

Action potential (AP)

In order to initiate an AP electrotonic depolarization is necessary to reach:

the threshold potential of __ or ___

A

voltage dependent (usually) Na+ or (in some tissues) voltage dependent Ca2+ channels.

32
Q

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 ____

A

activation (and then inactivation) of voltage dependent channels

33
Q

The membrane potential change is charecteristic “all or none” response
->True or false?

A

True

The membrane potential change is charecteristic “all or none” response f

34
Q

Cells which are capable of AP production are called ___

A

“excitable”

35
Q

Draw an AP graph

36
Q

Series of events during a typical action potential

37
Q

Conductance changes during the action potential
-> Fill in the gap

38
Q

Alterations of the excitabiliy during the AP.
-> Fill in the gap

39
Q

Alterations of the excitabiliy during the AP.
-> Identify green and yellow parts

40
Q

Alterations of the excitabiliy during the AP.
-> identify

41
Q

Identify this action potential (AP) shape?

A

Neurons, skeletal muscle

42
Q

Identify this action potential (AP) shape?

A

Cardiac pacemaker tissue

43
Q

Identify this action potential (AP) shape?

A

Cardiac muscle

44
Q

AP of Neurons, skeletal muscle
-> What is happening here?

A
  • Local potential change
  • Graded potential
45
Q

Neurons, skeletal muscle AP
-> What is happening here?

A

Depolarization
-> Opening of voltage gated Na+ channel

46
Q

Neurons, skeletal muscle AP
-> What is happening here?

A

Repolarization
-> closure of Na+ and opening of K+, voltage gated channels

47
Q

Neurons, skeletal muscle AP
-> What is happening here?

A

Hyperpolarization
-> Voltage gated K+ channels remain open after the potential reaches resting level

48
Q

Neurons, skeletal muscle AP
-> What is happening here?

A
  1. Resting membrane potential (RMP)
  2. Threshold level
49
Q

AP shape of cardiac pacemaker tissue

50
Q

This is AP shape of Cardiac muscle
-> Identify the parts

51
Q

Characteristic of The conduction of the action potential in a myelinized axon?

A

It is „saltatoric” (jumps from one Ranvier node to the next) and
it’s speed can reach 100-120 m/s)

52
Q

Compare the space constant between thin axon and large axon

A

Large axon has a larger space constant

A Physiology (20 decks)

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