Action Potentials

Question 1

What is an action potential l

Answer 1

A change in voltage across a membrane

Question 2

Only when will an action potential occur

Answer 2

When it reaches the threshold potential

Question 3

Wherein the neurone are action potentials first produced

Answer 3

Axon hillock

Question 4

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

Answer 4

Closer to the equilibrium potential of that Ion

Question 5

What is membrane capacitance

Answer 5

Ability to store charge

Question 6

How many ion need to flow to generate an action potential

Answer 6

Very little due to large difference in Ion concentration

Question 7

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

Answer 7

Voltage clamp

Question 8

What causes depolarisation of the membrane

Answer 8

Sodium Ion influx

Question 9

What causes repolarisation of the membrane

Answer 9

Inactivation of sodium Channels and the opening of potassium Channels

Question 10

What is the absolute refractory Period

Answer 10

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

Question 11

What is the relative refractory period

Answer 11

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

Question 12

What allows sodium Channels to be activated again

Answer 12

Hyperpolarisation

Question 13

How many polypeptides make up a voltage Gated sodium channel

Answer 13

1

Question 14

Between which 2 TM domains is the pore region located

Answer 14

5th and 6th

Question 15

What is special about the 4th TM domain in VGICs

Answer 15

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

Question 16

What are sodium voltage Gated Channels susceptible too once open

Answer 16

Inactivation

Question 17

What blocks the pore region of sodium voltage Gated Channels

Answer 17

Inactivation particle

Question 18

How many subunit is a potassium Channels made up of

Answer 18

4

Question 19

What is procaine

Answer 19

A local anaesthetic

Question 20

How do anaesthetics work

Answer 20

Block sodium Channels

Question 21

Do thicker axon diameters result in faster or slower transmission

Answer 21

Faster

Question 22

What is the local current theory

Answer 22

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

Question 23

What does membrane resistance depend on

Answer 23

The number of Ion Channels that are open

Question 24

What does high resistance result in

Answer 24

The voltage spreading further along the axon

Question 25

What does high capacitance result in

Answer 25

Voltage changes occurring more slowly

Question 26

What is the effect of myelination

Answer 26

Insulate the axon and allows for faster conduction

Question 27

What are node of Ranvir

Answer 27

Gaps in the axon where no myelin sheath is found

Question 28

What are found in the nodes of Ranvir

Answer 28

Ion Channels

Question 29

What cells myelinate the axons in the CNS

Answer 29

Oligodendrites

Question 30

What type of cells myelinate the axons in the PNS

Answer 30

Schwann cell

Question 31

What does myelination result in

Answer 31

Salvatore conduction

Question 32

What is saltatory conduction

Answer 32

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

Question 33

How does myelination improve conduction

Answer 33

1. Increase in membrane resistance | 2. Decrease in membrane capacitance

Question 34

What is multiple sclerosis

Answer 34

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

Question 35

What does demyelination result in

Answer 35

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

Question 36

What does depolarisation to the threshold trigger

Answer 36

The opening of voltage Gated sodium Ion Channels

Question 37

What does depolarisation cause

Answer 37

Inactivation of sodium channel and opening of potassium Channels

Question 38

How is a signal passed from a neurone to a muscle

Answer 38

Through a neuromuscular junction

Question 39

What does depolarisation at the end of a neurone cause

Answer 39

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

Question 40

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

Answer 40

Release of neurotransmitter

Question 41

What is the extracellular concentration of calcium Ion in moles

Answer 41

1x10^-3

Question 42

What is the intracellular calcium Ion concentration in moles

Answer 42

1x10^-7

Question 43

What does increasing the frequency of action potential cause

Answer 43

More neurotransmitter to be released

Question 44

How many polypeptides are calcium Ion Channels made up of

Answer 44

1

Question 45

What type of Channels do DHP block

Answer 45

L type calcium Ion Channels

Question 46

What action does DHP block

Answer 46

Muscle contraction

Question 47

What does phosphorylation of VGIC cause

Answer 47

A change in activity

Question 48

What is calcium channel inactivation dependant on

Answer 48

Calcium Ion

Question 49

What neurotransmitter is used at neuromuscular junctions

Answer 49

Acetyl choline

Question 50

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

Answer 50

Synaptotagmin

Question 51

What does synaptotagmin do

Answer 51

Brings the vesicle close to the membrane

Question 52

What is the function of the SNARE complex

Answer 52

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

Question 53

What does curare do

Answer 53

Block transmission between nerves and muscles s

Question 54

What is a competitive blocker

Answer 54

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

Question 55

Give an example of a competitive blocker

Answer 55

D-tubocurarine

Question 56

What is a depolarising blocker

Answer 56

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

Question 57

Give an example of a depolarising blocker

Answer 57

Succinylcholine

Question 58

What is mayasthenia gravis

Answer 58

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

Question 59

What symptoms are associated with mayasthenia gravis

Answer 59

Weakness which increases with exercise

Question 60

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

Answer 60

Nicotinic are ligand gates whereas muscarinic are GPCRs

Question 61

What does it mean by an all or nothing Response

Answer 61

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

Question 62

What is an inactivate channel

Answer 62

One that is open but doesn't allow ions through