Drugs Affecting Nerve Excitability Flashcards
What is the difference between an analgesic and an anasethetic?
anaesthetics reversibly eliminate sensation by blocking nerve function whereas analgesics just relieve pain by targeting a chemical pathway
Where do analgesics work?
everywhere
Where do local anaesthetics work?
in the peripheral nerve
Where do general anaesthetics work?
in the central nervous system
What are the three types of local anaesthetics?
aminoesters, aminoamides and benzocaines
What is the difference between an aminoester local anaesthetics and an aminoamide local anaesthetics?
aminoamides are longer acting because they are not as rapidly metabolised
What is procaine?
an aminoester local anaesthetic
What is lignocaine, bupivicaine and ropivicaine?
aminoamide local anaesthetics
Why are sensory nerves more sensitive to local anaesthetic than motor nerve?
because their sodium channels are more accessible because they are less myelinated
What is the site of action of local anaesthetics?
intracellular side of the sodium channel
What are the two mechanisms of action of local anaesthetics and how do they work?
hydrophobic and hydrophilic
hydrophobic - doesnt matter whether the channel is open or closed so works fast and is non use dependent
hydrophilic - nerve needs to be active so the channel is open so it can gain access so works slower and is use dependent
Which local anaesthetic has a hydrophobic mechanism?
benzocaine
What type of nerve fibres are more sensitive to local anaesthetics?
small fibres so sensory > ANS > motor
Do general anaesthetics cause a change in resting membrane potential?
No - they just stabilise the axon membrane
Is the effect of general anaesthetics more pronounced in an acidic or a basic medium?
basic
