Muscle contraction question

Just to confirm, the A band remains the same width while the I band becomes narrower when the muscle is contracting, right?
And by “band”, it doesn’t exactly mean actin or myosin, right? If I understand it correctly, bands only represent different part in the myofibrils.
So, although I band only contains actin and becomes narrower, it doesn’t mean actin itself will be shortened, right?
In fact, if I’m correct, both actin and myosin don’t change length when contracting muscle, they only move their places, right?

Check out slides i my teaching PowerPoint file at-d (sorry - to follow) - concentrate on slides 16 onwards, and all will become clear.M

The actin and myosin filaments slide relative to each other when muscle contracts - the I band (yes you are right, it has actin only) is the part from the end of one myosin fibre to the start of the adjacent myosin fibre - so naturally, as the myosin fibres slide and get closer to each other, the I band shortens.

Check out slides i my teaching PowerPoint file at-d (sorry - to follow) - concentrate on slides 16 onwards, and all will become clear.

M

Sorry young man, I am getting this error when trying to attach file since last night - still not sorted!
My site is still under construction, but will try to upload onto it for you as soon as I can - I realize that exams are upon you boys and girls!