Hi! I have a question regarding the muscle contraction. I was wondering, if the A bands contain thin filaments (actin filaments), why during muscle contraction they do not shorten, if actin filaments slide towards each other?
That’s a great question, although the A band contain both actin and myosin, the length of the A band is only the length of the myosin
When the muscle contracts the actin slides thus shortening the I band
The myosin does not change length, thus the A band does not change length
Hope this helps!