A2 Biology (Need some help)

So longitudinal muscle runs the whole length of a tube and circular muscle wraps itself around a tube. Longitudinal muscle is involved in shortening the tube and circular muscle is involved in constricting the tube. Longitudinal muscle is therefore involved in moving things through a tube, e.g. peristalsis in the gut, if you think of it like this, if you shorten part of the gut using longitudinal muscle, and then have a wave of circular muscle contraction move a long the gut while relaxing the longitudinal muscle, then you're going to squeeze the contents a long the bowel, kind of like squeezing a tube of toothpaste and runnign your hand a long it. Blood vessels don't need to do this, because blood has large pressure differences to get from one end of the tube to the other, so blood vessels just need circular muscle to constrict, they don't need to shorten.

If there's anything else you're stuck on then just ask, you specifically mentioned the question about longitudinal and circular muscle so I only answered that!

OHH That actually makes sense. But you say the longitudinal muscle makes waves of circular muscle contraction. How does it exactly do that? So how does a longitudinal muscle make those type of contractions? I'm sure im missing something so do you mind clarifying that up? Thanks