The structure of a skeletal muscle?

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kpopfangirl
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#1
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#1
Can someone explain to me in depth the structure of a skeletal muscle, like I'm confused about the microfibrils and muscle fibres and where the Sarcolemma is located.

This is for ALevel biology AQA btw
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macpatgh-Sheldon
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Hi, (I like pop too! ],

I cannot actually provide you with a PhD thesis on it here, otherwise the TSR website will crash [in any case I am a one-finger typist, so it would take 10 years, by which time you will have finished your PhD anyway!

I will give you some pointers and keywords to google, which will then lead you to "in depth" info, yeah?

Muscle fibres consist of many microfibrils - you could think of muscle fibres as the sinewy "strands" you can see when you look at/gulp meat, if that makes sense - some highly competitive bodybuilders have muscles on which you can see these fibres [google images Serge Nubre to look at his pecs [pectoralis major muscles], who could burst a hot-water bottle by blowing into it [at least that's what my grandad told me!!

Microfibrils are individual muscle cells, which have a structure that is linear, with myosin and actin [micro]filaments that overlap each other and slide relative to each other during contraction of the muscle, thus shortening it.

There are cross-bridges between actin and myosin, which are "twisted" during contraction and drag the filaments relative to each other [oc ATP plays a crucial role here].

The prefix "sarco-" simply refers to muscle - sarcolemma means the plasmalemma [cell membrane] of a muscle cell - cf. sarcoplasmic reticulum is the ER of muscle cells.

The detailed electron microscopic structure of a muscle cell shows a series of transverse bands [which give the name "striated" muscle" to skeletal muscle] with each sarcomere having a Z line, A band, I band etc. If you want to learn an easy way to remember the details of these, do let me know.

Please google underlined terms.
Be safe!
M
Last edited by macpatgh-Sheldon; 5 months ago
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