1) You should know the labels...
Yup, together with the direction of impulse (shown with red breaking arrow)
2) You should know the labels' functions...
Speaking of nodes of Ranvier (NOR), diagram below shows how it works:
|The impulse seems to 'jump' across the NOR to gain the speed.|
Finally, we just realized a special relationship between the myelin sheath & the axon. Here is how I put it :-)