Action Potentials Flashcards

1
Q

Why are AP’s imp for dentists

A

for local anaesthesia and pain etc

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2
Q

what are the diffenret chemical singling of the body

A

short distance - synapse

long distance - hormones

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3
Q

how fast is the chemical singling in the body

A

relatively slow

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4
Q

what are the types of electrical signalling in the body

A

graded potentials

AP’s

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5
Q

what are graded potentials

A

short distance
vary
fizzle out at nerve endings

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6
Q

what are AP’s

A

long distance
all or none
fast 120m/s

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7
Q

is the nerve membrane a good insulator

A

no poor as phospholipids are leaky and in aq enviro

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8
Q

is the cytoplasm good conductor

A

no poor

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9
Q

what happens to signals in nerves over 2-3mm and what is this due to

A

decays

due to high resistance and poor insulation

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10
Q

what is used in nerves to help with propagations of signals

A

AP’s

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11
Q

what is a resting mem pot

A

Separation of opposite charges across a membrane

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12
Q

what causes a rest mem pot

A

perm of key ions
corn grad for key ions
gradients maintained by active transporters

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13
Q

do all cells have rest me pot

A

yes

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14
Q

what are excitable cells

A

nerve and muscle

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15
Q

what are the extra/intracellular conc and relative perm of Na, K an anion

A

Na
extra - 150
intra - 15
RP - 1

K
extra - 5
intra - 150
RP - 25-30

anion
extra - 0
intra - 65
RP - 0

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16
Q

roughly explain the Na/K pump

A

uses ATP
transports 3 Na out
2 K in
helps maintain conc grads

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17
Q

si the mem perm or imperm to K

A

perm at rest

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18
Q

what is the electrochem gradient for K

A

chemical - k out

electrical - protein anions cant flow out so k attracted in

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19
Q

what is the nernst value for K equilibrium potential

A

-90mV

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20
Q

what si the mem at rest like toward Na

A

much less perm to Na

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21
Q

what si the nernst eon value for Na

A

+60mV

22
Q

how si the resting mem potential formed

A

due to effects of K and Na

ion with > perm drives mem potential

23
Q

at rest what is the RMP closer to

A

K equilibrium potential

24
Q

what is the RMP based on

A

based upon all ions in goldman eqn

25
Q

what is the importance of -50mV

A

threshold for AP all or none

26
Q

what is depolarisation

A

going upward more positive cause potential to go up sodium channels open

27
Q

what happens after depolarisation overshoot

A

K channels delay open and Na channels inactivate rapid depolarisation
K out

28
Q

what is hyperpolarsation

A

below threshold K channels close and N channels reset

29
Q

what is the hodgkins cycle

A
threshold depo
Na channels open 
increase na perm 
Na moves into cell 
Depo
N channel open
30
Q

how do ‘caine’ anaesthetics affect he hodgkins cycle

A

hold Na channels reversibly closed

31
Q

what is AP propagation

A
local current flow to adjacent area 
raise pot to threshold 
voltage gated N channel open 
poitve feedback 
porpaget along axon
32
Q

what si a refractory period

A

time when cannot reactivate a Na channel

33
Q

what are th two types of refractory period

A

absolute and relative

34
Q

what is an absolute refractory period

A

Na channels not in rest configuration

an AP can’t occur

35
Q

what is a relative refractory period

A

K gates open
mem is hyper polarised
an AP can occur need larger stimulus

36
Q

what does a refractory period do in terms of directions

A

means that nerve signals cannot backfire only propagated in one direction

37
Q

what does the width of an axon do to conduction velocity

A

increase axon diameter
lower resistance
faster conduction

38
Q

what does myelination do to conduction velocity

A

insulates
node ranvier jumps
local current flow node to node
depo jumps

39
Q

what re the types of nerve fibres

A

C
A delta
A beta
A alpha

40
Q

what does a C nerve do

A

slow burning pain
high resistance coz thin and non myelin
smallest nerve slow velocity

41
Q

what is a A delt nerve

A

faster sharp pain

myelin sheath so faster condition and is wider

42
Q

what is a A beta nerve

A

wider and myelinated

sensory ones, mechanoreceps

43
Q

what is a A alpha

A

biggest nerve
motor to muscles
widest and myelinated

44
Q

why rent all nerve A alpha

A

to big to fit in body need small to fit in places or would be huge

45
Q

what re incoming nerves

A

afferent from periphery to centre

46
Q

what are outgoing nerves

A

efferent from center to periphery

47
Q

what are the fastest nerves linked to

A

proprioception - knowing about self form and what body doing

48
Q

what is good to keep in mind about nerve size with dentistry

A

affects diff with LA

49
Q

what are the easiest yes of nerves to block

A

smallest most difficult widest

50
Q

what are he first type of nerves to be blocked

A

pain then touch