Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BDS2 LA Symposium > Local Anaesthetics > Flashcards

Local Anaesthetics Flashcards

1
Q

what is the functions of local anaesthetics?

A

LAs stop nerve conduction by blocking the voltage-gated Na+ channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

some nerve axons differ in their susceptibility to be blocked by LA, in what order are the nerves blocked?

A
  • A-delta
  • C fibres
  • A-beta
  • A-alpha
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the functions of A-alpha fibres?

A
  • sensory (proprioception)

- motor (skeletal muscle)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the function of A-beta fibres?

A

sensory (mechanoreception)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the function of A-delta fibres?

A
  • sensory (mechano, thermo, noci & chemo-receptors)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the mechanism of action of local anaesthetic?

A
  • LA binds to a site in the Na+ channel
  • LA blocks the channel and prevents Na+ influx
  • this blocks action potential generation and propagation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what can occur if LA reaches the bloodstream?

A

it can cause bradycardia and hypotension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what type of molecules are Local Anaesthetics?

A

organic molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are the three components of the organic local anaesthetic molecules?

A
  • aromatic region
  • ester or amide bond
  • basic amine side chain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

local anaesthetics are partly dissociated, what does this mean?

A
  • active in ionised form

- can cross membrane only in un-ionised form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

why are smaller diameter axons more susceptible to LA block?

A
  • less sodium channels in small fibres

- less channels at the axoplasm = less LA needed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the AXOPLASM of a nerve?

A

where the channels are located

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

where are the Na+ and K+ found in myelinated axons?

A

sodium and potassium ion channels are concentrated at the nodes of Ranvier
- nodes of Ranvier are exposed to the local anaesthetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

if a local anaesthetic is going to block a myelinated axon, what must it do? why is this?

A
  • to block the AP, the LA needs to act on several nodes of Ranvier along the axon
  • if only one node is blocked, the AP current is strong enough to flow past the blocked region & regenerate the AP at the next node of Ranvier
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is an example of an ester local anaesthetic?

A

benzocaine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is are examples of amide local anaesthetics?

A
  • lignocaine
  • prilocaine
  • articaine
  • bupivicaine
17
Q

how do local anaesthetics (by themselves) affect the blood vessels? why is this a problem?

A

they are vasodilators

- increased blood flow will increase ‘wash out’ of LA

18
Q

how is the duration of action of Local Anaesthetics increased?

A

LA preparations also include a vasoconstrictor

19
Q

what are examples of vasoconstrictors used in LA preparations?

A
  • adrenaline

- felypressin

20
Q

what are the different types of adrenoreceptors?

A
  • alpha receptors
  • beta 2 receptors
  • beta 1 receptors (cardiac muscle)
21
Q

what does stimulation of alpha adrenoreceptors cause?

A

vasoconstriction

22
Q

what does activation of beta 2 adrenoreceptors cause?

A

vasodilation

23
Q

if beta 1 adrenoreceptors are stimulated, what effect does this have on the cardiac muscle?

A
  • increases heart rate

- increased pumping force

24
Q

what effect does adrenaline have on adrenoreceptors?

A
  • vasoconstrictor effect (action on alpha receptors)

- lowers TPR (total peripheral resistance)

25
Q

what effect does adrenaline have on the heart?

A

increased cardiac output

26
Q

what effect does adrenaline have on mean arterial BP?

A

little or no effect

27
Q

what effect does noradrenaline have on alpha and beta adrenoreceptors?

A
  • more effective on alpha than on beta receptors
  • given locally it has a vasoconstrictor effect
  • systemically it increases TPR (total peripheral resistance)
28
Q

what effect does noradrenaline have on the heart?

A

increases cardiac output

29
Q

wha effect does noradrenaline have on mean arterial BP?

A

raises mean arterial BP

- this can result in a FALL of BP (& is why noradrenaline is not used)

30
Q

what is the difference in duration of action between ester and amide local anaesthetics?

A 
ester = brief action 
amide = longer duration of action
31
Q

what is surface application local anaesthetic also known as?

A

topical anaesthetic

BDS2 LA Symposium (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions