muscles

• what does the A band contain?


  both actin and myosin filaments
• what does the H zone contain?


  just myosin
• what is the name Z line to Z line?


  Sarcomere
• what does the I band contain?


  only actin
• what is the M line?


  the middle of the sarcomere
• what fibres will be seen in a contracted muscle?


  Actin and myosin from the A band
• what do muscle fibres contain?

  Myofibrils , sarcolemma, sarcoplasm , sarcoplasmic reticulum and mitochondria
• what is the sliding filament theory?


  1)action potential arrives at NMJ causing calcium ions to be released from sarcoplasmic reticulum

  2)calcium binds with tropomyosin changing its shape and revealing binding site

  3)myosin head binds forming cross bridges , causes angle change and releases ADP and phosphate pulling filaments into centre

  4)ATP binds to myosin head releasing it from site , ATP hydrolase provide energy for head to return to position

  5)repeated with new site
• how can ATP be formed from phosphocreatine?


  Creatine kinase breaks down PCR so that its phosphate can bind with ADP producing ATP for short bursts of exercise
• features of a fast twitch muscle?


  pale , little mitochondria and myoglobin , thick , lots of phosphocreatine and rapid contraction
• features of slow twitch muscles?


  dark red , much slower , lots of mitochondria and myoglobin they can hold it for longer and have a higher affinity for o2