Structure Of A Muscle

Question 1

Explain the structure of a muscle..

Answer 1

1) the muscle is surrounded by the epimysuim
2) bunches of muscle fibres are surrounded by the perimysuim
3) individual muscle fibres are surrounded by the endomysuim
4) each muscle fibre is made up myofibrils

Question 2

What is the sarcoplasmic reticulum?

Answer 2

Surrounds the myofibrils which contain calcium ions which are released for muscle contraction

Question 3

What 2 types of proteins do myofibrils contain?

Answer 3

Actin = thin filaments 
Myosin = thick filaments 

They run in a repetitive pattern called sarcomeres

Question 4

What is the process for huxley’s sliding filament theory?

Answer 4

1) an action potential is received
2) calcium ions are released from the sarcoplasmic reticulum to the sarcomere
3) calcium attaches the the troponin on the myotroponin and moves it to reveal the binding sites on the actin
4) the my son crossbridges attach ATP to the binding sites and ATP is broken down by myosin ATPase and this energy is used for a power stroke to slide the actin along the myosin
5) the muscle contracts at the H zone decreases an Z lines comes closer together
6) crossbridges return when ATP is broken down untill ATP returns back on
7) the action potential stops and calcium ions returns to the sarcoplasmic reticulum and the tropomyosin returns over the binding sites

Question 5

What’s is the ratchet mechanism?

Answer 5

The sliding filaments are believed to work like a ratchet mechanism where crossbridges constantly attach and detach.
This pulls the z lines together and H zones disappears

Question 6

What are skeletal muscles also known as?

Answer 6

Voluntary, striped or striated