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Pharmacology > Action Potentials > Flashcards

Action Potentials Flashcards

1
Q

What is an action potential l

A

A change in voltage across a membrane

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2
Q

Only when will an action potential occur

A

When it reaches the threshold potential

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3
Q

Wherein the neurone are action potentials first produced

A

Axon hillock

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4
Q

Where will the membrane potential move if the conductance of an Ion increases

A

Closer to the equilibrium potential of that Ion

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5
Q

What is membrane capacitance

A

Ability to store charge

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6
Q

How many ion need to flow to generate an action potential

A

Very little due to large difference in Ion concentration

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7
Q

What piece of equipment allows Ohio to measure membrane currents at a set potential

A

Voltage clamp

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8
Q

What causes depolarisation of the membrane

A

Sodium Ion influx

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9
Q

What causes repolarisation of the membrane

A

Inactivation of sodium Channels and the opening of potassium Channels

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10
Q

What is the absolute refractory Period

A

When an action potential can’t be generate despite the strength in stimulus

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11
Q

What is the relative refractory period

A

When an action potential can only be generated in response to a large stimulus

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12
Q

What allows sodium Channels to be activated again

A

Hyperpolarisation

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13
Q

How many polypeptides make up a voltage Gated sodium channel

A

1

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14
Q

Between which 2 TM domains is the pore region located

A

5th and 6th

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15
Q

What is special about the 4th TM domain in VGICs

A

It contains positive amino acids which causes a conformational change in response to depolarisation

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16
Q

What are sodium voltage Gated Channels susceptible too once open

A

Inactivation

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17
Q

What blocks the pore region of sodium voltage Gated Channels

A

Inactivation particle

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18
Q

How many subunit is a potassium Channels made up of

A

4

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19
Q

What is procaine

A

A local anaesthetic

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20
Q

How do anaesthetics work

A

Block sodium Channels

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21
Q

Do thicker axon diameters result in faster or slower transmission

A

Faster

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22
Q

What is the local current theory

A

How Na will entered an axon and move towards the negative region, spreading the depolarisation along he axon

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23
Q

What does membrane resistance depend on

A

The number of Ion Channels that are open

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24
Q

What does high resistance result in

A

The voltage spreading further along the axon

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25
Q

What does high capacitance result in

A

Voltage changes occurring more slowly

26
Q

What is the effect of myelination

A

Insulate the axon and allows for faster conduction

27
Q

What are node of Ranvir

A

Gaps in the axon where no myelin sheath is found

28
Q

What are found in the nodes of Ranvir

A

Ion Channels

29
Q

What cells myelinate the axons in the CNS

A

Oligodendrites

30
Q

What type of cells myelinate the axons in the PNS

A

Schwann cell

31
Q

What does myelination result in

A

Salvatore conduction

32
Q

What is saltatory conduction

A

When action potentials jump from node to node as sodium Ion travel between the node of Ranvir

33
Q

How does myelination improve conduction

A
  1. Increase in membrane resistance

2. Decrease in membrane capacitance

34
Q

What is multiple sclerosis

A

An autoimmune disease that results in demyelination of axons in the CNS

35
Q

What does demyelination result in

A

Poorer transmission as the axon may not be able to reach the threshold potential in these areas

36
Q

What does depolarisation to the threshold trigger

A

The opening of voltage Gated sodium Ion Channels

37
Q

What does depolarisation cause

A

Inactivation of sodium channel and opening of potassium Channels

38
Q

How is a signal passed from a neurone to a muscle

A

Through a neuromuscular junction

39
Q

What does depolarisation at the end of a neurone cause

A

Opening of calcium voltage Gated Ion Channels so calcium Ion move in

40
Q

What does the influx of calcium ions at the end of a neurone cause

A

Release of neurotransmitter

41
Q

What is the extracellular concentration of calcium Ion in moles

A

1x10^-3

42
Q

What is the intracellular calcium Ion concentration in moles

A

1x10^-7

43
Q

What does increasing the frequency of action potential cause

A

More neurotransmitter to be released

44
Q

How many polypeptides are calcium Ion Channels made up of

A

1

45
Q

What type of Channels do DHP block

A

L type calcium Ion Channels

46
Q

What action does DHP block

A

Muscle contraction

47
Q

What does phosphorylation of VGIC cause

A

A change in activity

48
Q

What is calcium channel inactivation dependant on

A

Calcium Ion

49
Q

What neurotransmitter is used at neuromuscular junctions

A

Acetyl choline

50
Q

What does calcium ions bind to once they enter the pre synaptic bulb

A

Synaptotagmin

51
Q

What does synaptotagmin do

A

Brings the vesicle close to the membrane

52
Q

What is the function of the SNARE complex

A

Makes a fusion pore in the membrane for the neurotransmitter the be released through

53
Q

What does curare do

A

Block transmission between nerves and muscles s

54
Q

What is a competitive blocker

A

A ligand that binds to nAChR and prevents the channel from opening

55
Q

Give an example of a competitive blocker

A

D-tubocurarine

56
Q

What is a depolarising blocker

A

A ligand that bind the nAChR and doesn’t allow it to close. This maintains depolarisation meaning that sodium Channels can’t become activated again

57
Q

Give an example of a depolarising blocker

A

Succinylcholine

58
Q

What is mayasthenia gravis

A

Autoimmune disease targeting nAChRso you have a loss of function of these receptors and so no depolarisation

59
Q

What symptoms are associated with mayasthenia gravis

A

Weakness which increases with exercise

60
Q

What is the difference I. Structure between nicotinic and muscarinic AChR

A

Nicotinic are ligand gates whereas muscarinic are GPCRs

61
Q

What does it mean by an all or nothing Response

A

An action potential will either be conduction along th whole length of the neurone or not

62
Q

What is an inactivate channel

A

One that is open but doesn’t allow ions through

Pharmacology (12 decks)

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