🥩 The Sliding Filament Theory of Muscle Contraction

How do muscles contract? Glad you should ask. Look in any book and you’ll probably be scarred and put off completely. I know I was! I mean what is the deal with Z line, A band, I band…?!


So let’s look into it very gently indeed. First off, a good idea about what muscles look like on a bigger scale:



The muscle is attached to the bone (spot the nice bone marrow) by the tendon. Muscle cells have a plasma membrane and cytoplasm much like any other cells, but each has a special name. The membrane is called sarcolemma while the cytoplasm is called sarcoplasm (it has a much higher glycogen storage content).


The basic unit of muscle tissue is the myofibril which has a tube-like shape and is made up of the muscle cells themselves. These look fibrous and are organised into…