Practical Test Lecture Breakdown

Seite 1

Learn the diagram on the connections from the nerve and electrode.

The nerve was taken kept moisturized. left side is thick, right side is thin. Cathode is at thick end and is stimulated and recorded at the anode to measure transmembrane potential difference between 2 recording electrodes.

A.

We looked at a diphasic cap, it is diphasic because we are recording potential difference as it states so in page 5 . We started from low stimulus intensity. As we increased stim intensity we saw a cap. As stimulus intensity is increased, more axons are recruited and we are able to get a maximum response as we recruited more fibres.

B.

Monophasic CAP

We didn't allow them to reach 2nd recording electrode so that we do not get interference from the 2nd electrode.

C

We measured amplitude and duration of monophasic CAP to understanding underlying physiology. Factors determining amplitude and duration due to axon recruitment. The number of axons recruited, duration is due to axonal features due to conduction velocity so the axons with the fastest conduction velocity. Stim int inc cause incr duration as there is enough current drive depolarisation in the regenerative ap in the slower conduc fibres there have small diameter and receive less current so they neeed more intensity and cause the tail.

Understand Conduction velocity Mitcheson lectures.

D.

Absolute and relative refact of the3 CAP.

We see the factors that affect the abso and rele of axons but focus on how it affects the CAP.

All axons of CAP1 are stimulated once again in CAP2 but what we saw was that a decrease in interval caused it to stay the same a few times then it started to decrease until it disappeared. We calculated the excitability (CAP2/CAP1) . The compound action potential was in Absolute refractory period at the beginning and Relative refractory period.

Undestand basis of ARP and RRP of CAP. and a single axon

Understand basis of ARP and RRP of an AP.

we decreased stimulus intensity to no response and we started to restimulate, we received a little CAP. As the axons had contributed to the second AP they must have been in their RRP. Original axons who managed to make a high ap are still in absolute refractory period.

E,

Conduction velocity

Speed=Distance/time

We had the distance of the nerve between the 2 recording electrodes to calculate speed. We can take this distance and divide it over time. Depending on whether we wanted to know the fastest conducting ap we would divide by time to onset. If we wanted an average we would use the time to peak. If we used the time to baseline it would tell us the time it took for the slowest conducting AP

Gradient=Y/X

1/gradient=speed