(eli5) How do muscles contract on a molecular level?
In: Chemistry
Im not 100% sure on the molecular level, but I imagine it has to do with complicated protein folding. Something to the tune of a relatively large protein molecule that, when introduced to some sort of stimulus (at a guess, probably either an electric shock or a particular enzyme) refolds itself into a more compact form. Probably has to do with hydrogen bonds and/or van der whaal’s interactions
There are two main proteins in muscle called myosin and actin. Myosin has little clublike parts that attach to the long skinny actin. In response to a tiny change in cell chemistry the myosin clubs bind and release onto the actin so the myosin “walks” along the actin and the whole myosin / actin unit gets shorter and fatter. Multiply this by many thousands of units and the whole muscle fibre gets shorter and fatter. Multiply that by the number of fibres in action and the whole muscle gets shorter and fatter.
Short answer, electricity
Longer answer, our brains sends charged signals throughout the body through the use of the nervous system. The nervous system is comprised of the central nervous system, the peripheral, sympathetic and parasympathetic nervous systems. In the brain there is approx 100,000,000,000 neurons. Comprised of the normal parts of cells, nucleus, cytoplasm and membrane aswell as axons and dendrites. These parts can communicate over longer distances with eachother and a cluster of axons creates a nerve. The nervous system is responsible for a whole host of things like volunteery movement, receiving light and sound information, moderating involuntary movements like breathing, blood pressure and heart rate and regulating bodily functions like temperature. In terms of movement when we consciously tell our body to do something the neurons pick up that signal and release a chemical via the spinal cord to the relevant axon clusters that then in turn communicate with the muscle fibres and cause the necessary extensions and contractions at a cellular level. Really it is the (as mentioned below, myosin and actin In the cell membrane) of these fibres that picks up these electric signals and sets of the relevant chain of events through certain proteins not overly confident enough in bio to get more elaborate but I hope this helps
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