Question

Refer to the diagram showing an electrical impulse moving through an axon to answer Questions
Diagram: http://www.flickr.com/photos/75076055@N05/6925855846/
Which sections of the diagram show the actual transmission of an impulse inside the axon's membrane?
and
Which area is a section of an axon in a state of rest?

Answer 1

Hey there,

In a state of rest, there is no net movement of ions. The axon is ready for the next impulse to come its way...so looking at the diagram, which choice would you consider the resting state axon to be?

Answer 2

The transmission of a signal through an axon results from extensive depolarization (influx of positive ions - specifically, sodium in this case - through voltage gated ion channels). First, there needs to be a signal of some sort. This signal causes the axon to begin to depolarize...once the axon hits the threshold (about -55mV) the voltage gated ion channels completely open, allowing sodium to rush in.

Following this positive spike , the potassium channels along the axon open, allowing potassium to flow back out. This is called hyperpolarization: the efflux of positive potassium causes the axon to drop once more into a negative charge.

The sodium potassium pump restores this imbalance: potassium gets pumped back in, and sodium gets pumped back out. As a result of the pump, the resting membrane potential is achieved (-70 mV).

Hopefully you should be able figure out those two questions now! To test you a bit more - which directino (right or left) is the signal travelling?