Anaesthetics

Question 1

What is the primary anatomical target of local anaesthetics?

Answer 1

Peripheral nerves

Question 2

What is the primary anatomical target of analgesics?

Answer 2

Peripheral nerves, spinal cord and thalamus

Question 3

What is the primary anatomical target of general anaesthetics?

Answer 3

Thalamus

Question 4

Which ion channels do local anaesthetics target?

Answer 4

Sodium channels

Question 5

Are local anaesthetics strong/weak … acids/bases?

Answer 5

Weak bases

Question 6

What types of tissues can local anaesthetics affect?

Answer 6

Excitable ie peripheral nerves, autonomic nerves and heart

Question 7

How do local anaesthetics work?

Answer 7

Bind to an intracellular domain of the sodium channel in neurones, disrupting conduction of nerve impulses at the axonal membrane

Question 8

Why are hydrophobic local anaesthetics like benzocaine non use-dependent (ie work fine whether or not the nerve is firing)?

Answer 8

Because they usually exists in their non-ionised form so they can diffuse across the cell membrane to bind to the intracellular domain of the sodium channel

Question 9

Why are hydrophilic local anaesthetics like lignocaine use-dependent (ie work better when the nerve is firing)?

Answer 9

Because they require sodium channels to be open to gain entry to the cell in its non-ionised form

Question 10

What sized nerve fibres are more sensitive to local anaesthetics?

Answer 10

Small fibres

Question 11

What effects do local anaesthetics have on the resting membrane potential?

Answer 11

None

Question 12

What are some possible side effects of local anaesthetics?

Answer 12

Myocardial depression, hypotension, CNS excitation, tremor, convulsion, respiratory arrest, allergic reaction