action potential

[jaja]

if the minium threshold of a sensory neuron was 3 impulse per second
could this impulse pass to the interneuron (minium threshold 4) and motor neuron (minium threshold 6) or motor neuron 2 (minium threshold

[n.f]

Yes it will pass to the interneuron but will not reach the interneuron's threshold to send the impulse on.
i/sec = impulses/sec below

Sensory (3)    -->  Interneuron (4)    --> Motor Neuron (6)/Motor Neuron 2 (
at 3i/sec, yes       at 3i/sec, no      WILL NOT PASS ON...


I assume multiple choice 17 from STAV 2006 was what you were referring to?
http://img32.imageshack.us/img32/2793/gfdgfd.png <--question uploaded here

[shinny]

Ah, yeh next time, type out the entire question because I got confused regarding whether 3 impulses/sec was actually sent or not, since you just said that was the minimum, not the actual amount sent. Well in this case, it's just testing the 'all-or-nothing' concept which says that depolarisation of nerves is a yes or no event which occurs only if the minimum is met. If the signal sent is only 3 impulses/sec, then the interneuron won't be stimulated since it requires 4.