Topic
Outcomes
Muscle Contraction
Level
A Level
1. To describe the structure of striated muscle
2. To describe the changes that place during muscle contraction
Muscle Structure and Contraction
Myofibrils (composed of myofilaments)  multinucleated muscle fibres (the
cells)
1. Striated muscle is said to be composed of parallel multinucleated fibres.
What does multinucleated mean?
2. What is the relationship between muscle fibres and myofibrils?
3. What do you call the characteristic cross striations along the myofibrils?
4. What is the region between two Z lines called?
5. Draw the arrangement of filaments in a sarcomere and label the diagram.
6. What are the names of the two myofilaments in the sarcomere?
7. Which filament is thick and which filament is thin?
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Muscle contraction:
8. When muscle contraction occurs what filaments are pulled in between the
myosin filaments?
9. Match the following chemicals to their function in muscle contraction.
Myosin
binds to actin molecules in a way that prevents myosin head from
forming a cross bridge
Actin
supplies energy for the flexing of the myosin ‘head’
Ca ions
has a moveable head that provides a power stroke when activated
Troponin-
two protein molecules twisted in a helix shape that form a thin
filament
Tropomyosin
ATP
bind to the blocking molecules, causing them to move and expose
the myosin binding site
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