1. a) Unmyelinated fibres are more sensitive to local anaesthetics because they are more easily blocked than myelinated fibres.

b) Touch, pressure and motor fibres are influenced by a-type fibres. These fibres are the final fibres that are blocked and therefore they are not sensitive to LA.

2. Local anaesthetics have an effect on both cardiovascular tissues and the Central nervous system tissues.

3. Local anaesthetics are chosen according to the type of procedure for which it is needed as well as the duration of the procedure.

4. Carbon dioxide raises the concentration used effectively of the nonionized form of the LA, this helps as only the nonionized form of the LA can cross the plasma membrane. Therefore the onset of action is faster.

5. Surface active anaesthetics: Benzocaine, Cocaine and Oxybuprocaine.