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Physiology > Voltage gated ion channels > Flashcards

Voltage gated ion channels Flashcards

1
Q

Ligand gated channels in the soma contribute how to the signal propagation?

A

Activation of voltage sensitive channels

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2
Q

How many alpha subunits does the voltage-gated sodium channel have?

A

4 repeats

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3
Q

How many times does the voltage-gated sodium channel pass through the membrane?

A

4

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4
Q

Where is the inactivation gate located?

A

Between repeats III and IV

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5
Q

What types of voltage-gated sodium channels are located in the CNS?

A

Nav1.1
Nav1.2
Nav1.3

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6
Q

How long is the transition of a voltage-gated sodium channel from activated to inactivated?

A

1ms

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7
Q

What is the Pk:PNa ratio for voltage-gated Na+ channels?

A

0.08:1

~1 K+: 10Na+

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8
Q

What factors is inactivation dependent on?

A

Time & voltage

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9
Q

What causes Nav inactivation?

A

Hinged lid or ball and chain in cytosol

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10
Q

What’s the typical amount of time necessary for deinactivation of Nav?

A

20ms

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11
Q

Where is the hinged lid located?

A

Between repeats 3 & 4

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12
Q

What amino acids form the hinged lid?

A

Isleucine
Phenylalanine
Methionine

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13
Q

All Na channels inactivate in what amount of time?

A

less than 5 ms

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14
Q

What local anesthetics are most commonly used, and how do they work?

A

LIdocaine and bupivacaine blocks voltage-gated ion channels

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15
Q

How does TTX induce death?

A

BLocks Na+ channel

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16
Q

How much TTX is needed to induce death?

A

1 micromol

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17
Q

HYPP is due to a defect in what type of channels?

A

Nav1.4

18
Q

Describe the pathway of HYPP

A

Increase in ECF causes small membrane depolarization
Opens Na+ channels
Fault Na+ channels do not inactivate
Efflux of intracellular K+

19
Q

How many alpha subunits make a Kv channel?

A

4

20
Q

What are the common K+ channel motifs?

A

Kv1.1
Kv1.2
Kv2.1
Kv2.2

21
Q

Can K channels ave mixed motifs?

A

Yes but only 1s with 1s & 2s with 2s

22
Q

Which K+ channels are Ca2+ sensitive?

A

Kv2.1

Kv2.2

23
Q

Which K+ channels are targets for many pharmaceuticals?

A

erg - Kv11

24
Q

Does the K+ channel use the hinged lid or the ball and chain motif for inactivation? Where is it located?

A

Ball and chain

4-5 loop

25
Q

Which transmembrane segment of the K+ channel is the voltage sensor?

A

TM4

26
Q

What is the Pk:PNa ratio for K+channels?

A

10

27
Q

When do K+ channels activate?

A

At peak of action potential

28
Q

What subunit of Kv is necessar for de-inactivation?

A

Beta

29
Q

Nav channels use the hinged lid and Kv channels use the ball and chain inactivation method. Which method is more rapid?

A

Hinged lid (Nav)

30
Q

What happens if K+ channels are blocked?

A

Cell depolarizes

31
Q

How long does activation of K+ channels take?

A

1s

32
Q

What channels are responsible for the slight depolarization prior to an action potential?

A

Ligand-gated channels

33
Q

What channels are responsible for the action potential?

A

VOltage-gated channels

34
Q

What channels are responsible for the hyperpolarization after an action potential?

A

Voltage-gated channels

35
Q

Which channels have the biggest impact on cardiac cells but little impact on other cells?

A

Calcium channels

36
Q

What is the intracellular reglation of calcium channels?

A

Kinases & G-proteins

37
Q

Which transmembrane segment is responsible for inactivation timer of calcium channels?

A

TM6 repeat I

38
Q

What are the subunits of the calcium channel?

A

Apha, beta, gamma, delta

39
Q

Which calcium channel is important for cardiac muscle?

A

Cav1 (L-type)

40
Q

Which calcium channel targets the dorsal root ganglion?

A

Cav2 (P/N/R type)

41
Q

During Ca2+ influx, does Ca2+ diffuse far through the cell? Why is this important?

A

No

Because there can be different Ca2+ concentrations at different parts of a cell

Physiology (45 decks)

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