1. How does the sensitivity for blockade by a LA compare regarding the following types of fibers?

1. myelinated fibers with unmyelinated fibers 

Smaller and myelinated fibers are blocked more easily than when compared to larger and unmyelinated fibers. 

2. pressure/touch nerves with the dorsal nerves that transmit pain impulses?

Activated pain fibers fire faster (activated Na channel has the highest affinity for LA). Fibers in the middle of a thick nerve bundle are blocked slower than those fibers on the outside of the bundle. 

2. Make a list of the effects of LA on other tissues.

Heart; class 1 anti-arrythmic drugs (lidocaine blocks Na channels in the heart tissue causing anti-dysrhythmic effects)

Skeletal muscle; weak blocking action (thus no clinical application)

3. What is the basis for the selection of a LA?

The selection depends on the desired effect and the type of procedure which is going to be performed. It is also dependent on the duration of the procedure as well as the numbing effect required in the specific tissue. 

4. Why are LA solutions sometimes saturated with CO₂?

CO₂acts as a buffer for the LA and potentiates its effects. Furthermore, inhalation anesthetics can produce carbon monoxide (CO). CO binds to hemoglobin with high affinity, reducing oxygen delivery to tissues. CO production can be avoided by using fresh carbon dioxide absorbent and by preventing its complete desiccation.

5. Which of the LA are typically used for surface anesthesia?

Benzocaine (temporary pain relief in throat lozenges), Cocaine (ear, nose and eye surgery), Oxybuprocaine (opthamology)