how do muscles contract?
In: Biology
You can think of it almost like velcro. There are 2 strands, one is the hooks, the other side is the fabric that gets hooked on to. For a muscle to begin contracting, the hook side (myosin) will grab on to the fabric side (actin) and tug. This shortens the muscles a very small amount. To achieve a full contraction this process happens over and over again (cross bridge cycling) until there is no more room to shorten, or the force produced is no longer able to move the load. The actual process is called the sliding filament theory if you’d like to go in depth.
Imagine the muscle cell which is like a really long noodle, inside of it there are a bunch of proteins that are like “arms with hands” that can reach into other immovable proteins that are like “metallic poles” to which they can hold and pull into so they can approximate themselves to them. The hands need to grasp the pole so they can immediately pull themselves into it, but they aren’t doing so all the time because the hands are usually full, let’s say with rubber balls (This avoids that muscles are always contracting).
In voluntary muscle contraction, your brain sends a signal that ends up making the ball really uncomfortable to play with so the hand is no longer occupied with it and is now able to grasp into the metallic pole and is now able to pull itself to it.
The hand proteins are situated in such a way inside of the noodle-like muscle cell that even from two different directions they will always pull themselves to the center of it, making it shorter in length.
The orchestrated shortening of these structures cause cell fiber contraction, and the addition of all of the muscle cells contracting in the same direction at the same time causes muscle contraction.
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