Tuesday, May 22, 2012

How do muscles contract?

I spent a bit too long on immunology and ran out of time to cover muscles. Check out section 48.1 and 48.2 in your textbook which cover this quite clearly.

Note though that this 'sliding filament' model of muscle contraction was only discovered in the 1950's. The key evidence used to construct the model was a series of electron micrographs like those to the right of the picture.

You textbook does a nice job of interpreting the micrographs (figs 48.1 and 48.2) in the context of the theory but it's interesting to consider if you only had the pictures do you think you would have come up with the correct model?

The sliding filament model was actually proposed by two groups working independently and their papers were published together in the same issue of Nature.

 Structural changes in muscle during contraction: interference microscopy of living muscle fibres

Changes in the cross-striations of muscle during contraction and stretch and their structural interpretation 
In 2004 Nature published a special focus to celebrate the papers and look at progress in the subsequent decades on 'one of the most intriguing of biological problems: that of the conversion of chemical energy to mechanical work'.

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