1 / 13

The muscle fibre

The muscle fibre. Let’s go back to the individual muscle fibre The fibres are covered by a membrane called sarcolemma Between the muscle fibre and the sarcolemma membrane is a gel-like fluid called sarcoplasm

joanne
Download Presentation

The muscle fibre

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The muscle fibre Let’s go back to the individual muscle fibre • The fibres are covered by a membrane called sarcolemma • Between the muscle fibre and the sarcolemma membrane is a gel-like fluid called sarcoplasm • And then, as already learned, on the outside of each fibre’s sarcolemma is the connective endomysium tissue, that helps the fibres to bind

  2. Sarcoplasm • Sarcoplasm is liquid gold, it contains: • Mitochondria (where aerobic energy is made) • Myoglobin (carries oxygen to the mitochondria) • Energy nutrients (fat/protein/carbs) • Adenosine triphosphate (immediate energy) • Enzymes (chemicals to speed up energy production) • Actin and Myosinmyofilaments(proteins that help with contraction)

  3. The muscle fibre • Each muscle fibre is actually made up of long strands called myofibrils • Each myofibril contains many smaller units called Sarcomeres • Sarcomeres are responsible for muscular contraction, they contain two filaments called actin and myosin • Yes, we’re finally down to the smallest unit of the muscle!

  4. Sarcomeres • This is a contractile unit • It’s important to grasp that each myofibril contains many sarcomere, joined end to end

  5. Sarcomeres • The sarcomeres are lined up end to end along the myofibril. • Where the abut each other is called the Z-Line • Actin is a contractile protein (filament) that attaches to each of the z-lines • Myosin is another contractile protein that sits between the actin filaments

  6. Sarcomeres • I-Band = Actin only • A-Band = both, length of myosin • H-zone = myosin only, the gap between acton filaments (space for contraction)

  7. Sarcomeres • Myosin filaments have cross bridges – just picture little hockey stick type things.

  8. Sarcomeres • When the sarcomere contracts, the curved end of the hockey stick grabs onto the actin and pulls it towards the centre of the sarcomere. • This happens in all sarcomeres at the same time, making the muscle contract

  9. Sarcomeres • The muscle will relax when the myosin and actin lose contact with each other and the sarcomere returns to normal size. • Myosin doesn’t change in length during a contraction, actin does

  10. Muscular tone • There’s never a time when ALL myosin cross bridges have detached from the actin, some stay in contact • This gives us muscular tone – the muscle is never completely relaxed. • Because they’re already partially connected, they can be activated quickly. • Tone also helps with posture.

More Related