Muscle Contractions Flashcards
What is the sacolemma
Membrane
What is the myofibril
Block of protein, some thick some thin
What is the sarcomere
Single unit of muscle
The distance between adjacent Z-lines
What is the sarcoplasmic reticulum
Sack filled with calcium
Form of adaptation of the muscles
What 2 proteins are involved
Actin (thick)
Myosin (thin)
Why do myofibrils appear striped
Altering light coloured and dark coloured bands
A band = dark
(I band = light)
Why do A bands appear darker
Actin and myosin filaments overlap in this region
What is the H zone
Part of A band which is exclusively myosin
Why is the Z-line
Centre of each I band
What happens when the muscle contracts
Sacromeres shorten so pattern of dark and light bands change
What proteins are in actin’s structure
Actin
Tropomyosin
Troponin
What is a neuromuscular junction
Where motor neurone meets skeletal muscle fibre
Why are there many neuromuscular junctions spread through the muscle
Means can be quick muscle contractions as they simultaneously, making it powerful
This is essential for survival
What is the role of tropomyosin
Covers up myosin binding sites then shifts out of place to expose them and allow myosin to bind
Describe the cycle of muscle contraction
Calcium arrives, bonds to Troponin Causes Tropomyosin to pull away Myosin binding sites exposed Myosin binds to actin Myosin head pivots, causes actin to move ATP attaches, causing head to detach ATP hydrolysis provides energy for head to reposition Cycle continues as long as calcium present