15.6 - Structure of Skeletal Muscle Flashcards
The different types of muscle How skeletal muscles act in antagonistic pairs The structure of skeletal muscle fibres The components within muscle fibres that allow contraction The difference between fast-twitch and slow-twitch muscle fibres
What are the three types of muscle?
- Skeletal muscle - This muscle forms the majority of the body’s muscles and is attached to bones to voluntarily move parts of the body like the arms or legs.
- Cardiac muscle - This muscle is unique to the heart, and functions to involuntarily circulate blood.
- Smooth muscle - This muscle is located in the walls of hollow organs like blood vessels and the intestines, and typically functions to involuntarily move substances through these organs.
What is the function of skeletal muscle?
Voluntary movement of body parts
What is the function of cardiac muscle?
Involuntary circulation of blood
What is the function of smooth muscle?
Involuntary movement of substances through organs
How do skeletal muscles act?
In antagonistic pairs
What are antagonistic muscles?
Pairs of muscles working opposite each other
What is the sarcolemma?
Cell-surface membrane of muscle fibre
What is the sarcoplasm?
Cytoplasm of muscle fibre
What are T tubules?
Extensions of sarcolemma
What is the sarcoplasmic reticulum?
Specialised endoplasmic reticulum
What are myofibrils?
Subcellular structures for contraction
What is the structure of myofibrils?
Repeating units called sarcomeres
What are the main filaments in a sarcomere?
Myosin and actin
What is the A band?
Area with myosin and overlapping actin
What is the I band?
Area with only actin
What are Z-lines?
Boundaries of sarcomere
What is the M-line?
Central line of sarcomere
What is the H-zone?
Area with only myosin
What are slow-twitch muscle fibres adapted for?
Endurance work
What are adaptations of slow-twitch fibres?
Large myoglobin store
What are fast-twitch muscle fibres adapted for?
Intense short bursts of activity
What are adaptations of fast-twitch fibres?
More myosin
