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BMS109 Neuroscience > The Excitable Cell > Flashcards

The Excitable Cell Flashcards

1
Q

How are APs coded

A

frequency

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2
Q

Describe generation of an AP

A

all or nothing

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3
Q

Describe an AP

A

unit of size - fixed

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4
Q

What is the function of APs

A

travel along axons, in one direction

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5
Q

How are graded potentials coded

A

size

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6
Q

Describe graded potenitals

A

local signals that travel short distances, variable size

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7
Q

Which direction do graded potentials pass

A

can travel both ways

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8
Q

TRUE or FALSE - strength of stimulus affects strength of potential

A

True

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9
Q

What is the resting potential

A

when no potentials are produced

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10
Q

Describe the resting potential

A

negative - unequal distribution of charged molecules

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11
Q

What is charge of the resting membrane potential

A

-70mv ish

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12
Q

What physical forces control ion movements in solution

A

diffusion, electrical fields, ion movement

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13
Q

What does the nernst equation calculate

A

equilibrium potential for an ion

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14
Q

What channel is a key determinant of the resting potential

A

potassium channel

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15
Q

Why is the resting potential so important

A

required for functioning nervous system

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16
Q

What do ion pumps in membrane set up

A

ionic concentration gradient

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17
Q

Describe the effect of high intracellular Ca in neurons

A

toxic

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18
Q

Does calcium move in or out of neurons

A

out

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19
Q

What does the Goldman equation calculate

A

resting potential

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20
Q

What are the phases of an action potential

A

rising phase, overshoot, falling phase, undershoot

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21
Q

What are the majority of action potentials mediated by

A

changes in permeability for sodium

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22
Q

What are some action potentials mediated by

A

changes in permeability for calcium

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23
Q

When are APs mediated by changes in permeability for calcium important

A

developing nervous system

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24
Q

TRUE or FALSE - action potential propagation decreases along the axon

A

FALSE

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25
Q

When are all sodium channels closed

A

resting state

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26
Q

When do some of the sodium channels open

A

when membrane potential rises to -50mV

27
Q

Describe permeability changes of the membrane at -50mV

A

permeability for sodium increases, permeability for potassium decreases

28
Q

What does an influx of sodium cause

A

membrane depolarisation

29
Q

What happens when sodium channels close

A

repolarisation

30
Q

Describe permeability changes during repolarisation

A

permeability for potassium ions increase

31
Q

When are most of the potassium channels open

A

resting state

32
Q

describe the structure of voltage-gated sodium channels

A

complex proteins with 4 subunits

33
Q

Describe domain 4 of voltage gated sodium channels

A

special domain - positively charged AAs

34
Q

What is the function of domain 4 of voltage gated sodium channels

A

sense change in voltage

35
Q

Name some poisons affecting the excitable cell

A

Tetraethlyammonium, lidocaine, tetrodotoxin

36
Q

What is the effect of tetraethlyammonium on cells

A

blocks potassium channels

37
Q

What is the effect of lidocaine on cells

A

blocks Na+ channels - local anaesthietic

38
Q

What is the effect of tetrodotoxin on cells

A

blocks sodium channels

39
Q

Describe the rising phase of an action potential

A

rapid depolarisation

40
Q

What causes the rising phase of an action potential

A

influx of Na+ into neuron

41
Q

What happens during the falling phase of an action potential

A

voltage gated Na+ channels close, voltage gated K+ channels open

42
Q

What moves out of the neuron during the rising phase

A

K+

43
Q

How come an action potential only moves in one direction

A

sodium channels on one side are inactive

44
Q

What factors influence conduction velocity

A

myelination, diameter, permeability

45
Q

What does myelination act to increase

A

membrane resistance, space constant

46
Q

What is a disadvantage of myelination

A

high metabolic and volume cost

47
Q

What process do the nodes of ranvier induce

A

saltatory conduction

48
Q

When is myelination mainly used

A

long distances

49
Q

What does the space constant define

A

membrane potential decay

50
Q

Where are axon potentials generally generated?

A

axon hillock

51
Q

What type of potential do dendrites have?

A

graded potentials

52
Q

What does continuous stimulation of a neuron produce?

A

train of action potentials

53
Q

What is stimulus potential encoded by ?

A

action potential frequency

54
Q

What is a EPSP

A

excitatory post synaptic potential

55
Q

What is the effect of an EPSP

A

depolarises the membrane

56
Q

What is an IPSP

A

inhibitory post synaptic potential

57
Q

what is the effect of an IPSP

A

hyper polarises the membrane

58
Q

What is an IPSP a result of

A

activation of inhibitory receptors

59
Q

What are ionotropic receptors permeable for

A

chloride

60
Q

What are metabotropic receptors

A

GPCRs

61
Q

What are ionotropic receptors

A

ligand gated ion channels

62
Q

Which receptor is faster working - ionotropic or metabotropic

A

ionotropic

63
Q

TRUE or FALSE - Graded potentials can summate

A

TRUE

BMS109 Neuroscience (22 decks)

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