W19/L5: Anaesthetics Flashcards Preview

6. Neuro > W19/L5: Anaesthetics > Flashcards

Flashcards in W19/L5: Anaesthetics Deck (25):
1

How do local anaesthetic agents work?

They interfere with Na+ influx to block action potentials in sensory nerves

2

What's an example of an aminoester anaesthetic?

Procaine

3

What's the duration of action of aminoesters like?

Relatively short ~30min

4

Why do aminoesters have a short duration of action

they're hydrolysed by esterases (including AChE)

5

List 3 examples of aminoamide anaesthetics

Lignocaine
Bupivicaine
Ropivicaine

6

Why are the aminoamide anaesthetics longer acting?

They're metabolised hepatically

7

What's the local anaesthetic that doesn't have a family?

Benzocaine

8

What features of local anaesthetics make them safe?

They bind reversibly
There's no permanent nerve damage
They are administered in a way that limits systemic distribution

9

Describe the neural Na+ channel

Large protein with many TM domains.

Has two gates: M- and N-gate

10

Where on the Na+ channel do toxins usually bind?

On the extracellular side - usually causing complete & irreversible blockage.

11

Where on the Na+ channel do the local anaesthetics bind?

On the intracellular side

12

What are the two mechanisms of local anaesthetics interacting with the Na+ channel?

Hydrophobic and hydrophilic

13

How does the hydrophobic MoA of local anaesthetics work?

The drug in its uncharged form can enter the cell membrane and take position in the Na+ pore

14

*Skip the rest of this cause I think JZ's explanation is wrong. Look it up!

..

15

What are the commonly inhaled GAs?

Desflurane
Sevoflurane
Isoflurane

16

What are the common IV GA's?

Propofol
Thiopentone

17

How can GAs affect respiration?

Impaired ventilation
Depression of the resp. centre
Obstruction of airways due to retention of mucosal secretions

18

Why are anti-muscarinics often co-administered with GAs?

They decrease secretion -> reducing the likelihood of airway obstruction.

19

How can GAs affect the cardiovascular system?

Decrease vasomotor centre function
Depress contractility
Peripheral vasodilation
Cardiac arrhythmias
Inadequate response to fall in BP or CO

20

What are the two theorised MoA of GAs?

Lipid theory & receptor interaction theory

21

What is the lipid theory of GA MoA?

That GAs work by getting into the lipid membrane of axons, expanding and thus affecting activity

22

What evidence supports the lipid theory of GA MoA?

- There;s a close correlation between lipid solubility and anaesthetic potency

- Hyperbaric chambers can reverse anaesthesia

23

What is the receptor interaction theory of GA MoA?

That GAs work by enhancing inhibitory systems and inhibiting excitatory systems

24

What evidence supports the receptor interaction theory of GA MoA?

? Not actually sure - look this up!

25

What (broad) treatment goals do we have for Epilepsy?

Modify motor nerve output: Reduce exitation