1 Minute Recap – Smooth Muscle Contraction


After we really cover skeletal muscle in
depth, I’ve had a lot of questions today already in this week to try and explain
just going to recap the calmodulin system and how that works in smooth
muscle so we’ll go through it it should only take a minute
calcium in smooth muscle comes largely from the extracellular space little
pockets called alveoli and the calcium runs in here but it also comes from the
sarcoplasmic reticulum nowhere near like in skeletal muscle where the sarcoplasmic reticulum is a really specialized store of calcium in smooth muscle calcium
seeps out of it but regardless of how it gets there from the extracellular fluid or
the sarcoplasmic reticulum the calcium has one function here which is
to bind. And it activates calmodulin. Calmodulin really is just a
regulatory protein. It’s there as an on/off switch to get the contraction going or
to inhibit it and here’s what happens when we activate calmodulin
and when calcium binds to calmodulin it then goes and activates myosin
light-chain kinase and the activation of myosin light-chain kinase then moves on
to activate our myosin head and it’s this myosin head then that can start
crossbridge cycling and the minute that it gets activated we start getting that
same function crossbridge cycling is occurring and smooth muscle contraction
can commence

10 thoughts on “1 Minute Recap – Smooth Muscle Contraction”

  1. Doesn't the myosin light chain kinase activate and ATPase on the myosin head which hydrolyzes the ATP and causes myosin to bind to the actin binding site? Which then causes the muscle contraction?

  2. Took me a while to figure out that you’re not writing backwards! Your wrist watch gave you away! Great video btw

  3. You need to post more videos like this. I love the way you explain, it made me wanna learn more and more. I wish my professors in Faculty are like you…

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