Muscles Flashcards
What do muscles act in and what does this mean?
Antagonistic pairs - when the bicep contracts, the tricep relaxes
What are muscles attached to bones by and how do they produce movement?
Tendons, pull tendons
What are the new structures of muscles that need to be learnt?
Muscle fibre, myofibril, sarcomere, actin, myosin, sarcoplasmic reticulum, T-tubule, sarcolemma
What are actin and myosin?
Actin: thin filaments in myofibrils
Myosin: thick filaments in myofibrils
Where are the Z-lines and M-lines in a sarcomere?
Z-lines: end of sarcomere
M-lines: middle of sarcomere
What are the 3 bands in a sarcomere and what do they contain?
H-zone, A-band, I-band
H-zone: Myosin only
A-band: Myosin and actin
I-band: Actin only (inbetween myosin)
What will happen to the H-zone, A-band, and I-band when a muscle contracts?
H-zone shortens, A-band stays the same, I-band shortens
What is muscle contraction also known as and why?
Sliding filament theory - actin filaments slide over myosin filaments
Explain muscle contraction
- Action potentials depolarise sarcolemma and T-tubules
- Voltage-gated Ca2+ channels open on the sarcoplasmic reticulum membrane and Ca2+ ions diffuse into the myofibril
- Ca2+ ions attach to tropomyosin which moves and exposes myosin binding sites on actin
- Myosin heads bind actin, forming actinomyosin bridges
- Hydrolysis of ATP releases energy that causes myosin heads to bend and pull actin
- Binding of ATP to the myosin head causes it to detach from actin
- Myosin heads move back to their original position and reattach at binding sites further along the actin
What does phosphocreatine do?
Donates a phosphate to ADP to regenerate ATP in anaerobic conditions - when the muscle is relaxed, creatine phosphorylated back to phosphocreatine using Pi from ATP
Which respiration are slow fibres adapted for?
Aerobic
Which respiration are fast fibres adapted for?
Anaerobic
