Striated, voluntary, regularly arranged cells that contract in one direction, rapid contraction speed, short contraction length, muscle fibres are tubular and multinucleated
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Cardiac Muscle
Heart muscle, specialised striated, involuntary, intermediate contraction speed and length, fainter striations, fibres are branched and uninucleated
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Smooth Muscle
Non-striated, involuntary, no regular arrangement, different cells can contract different directions, slow contraction rate and con contract for long periods of time, fibres are spindle shaped and uninucleated
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In skeletal muscles, the bundles of muscle fibres are bound by a membrane, what is the membrane called?
Sarcolemma
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How come muscle fibres contain more than one nucleus?
During the development of the embryo, the embryonic muscle cells fused together to make the muscles stronger
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What is the shared cytoplasm called?
Sarcoplasm
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Why does parts of the sarcolemma fold inwards?
These are known as transverse (T) tubules, they help spread the electrical impulses throughout the sarcoplasm to ensure the fibre receives the impulse to contract at the same time
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How are muscle fibres adapted for contraction?
Lots of mitochondria to provide the ATP needed and modified endoplasmic reticulum known as sarcoplasmic reticulum stretching throughout fibres and contains lots of Ca ions needed
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What are myofibrils?
Long organelles specialised for contraction, they are made up of 2 proteins, actin and myosin
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Actin
Thinner filament, 2 strands entwined around each other
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Myosin
Thicker filament, has long rod-shaped projections with bulbous heads
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Structure of myofibrils
Alternating light and dark bands, giving its striped appearance
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Light bands
Isotopic/I bands, where myosin and actin filaments don't overlap
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Dark bands
Anisotropic/A bands, where the thick myosin filaments are present and the edges are darker as the myosin is overlapped with actin
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Z-line
The line in the centre of each light band
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H-zone
the lighter coloured region in the anisotropic bands where only myosin filaments are present
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Sarcomere
The region in between 2 Z-lines, the functional unit of the myofibril, when muscle contracts the sarcomere shortens
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Other cards in this set
Card 2
Front
Skeletal muscle
Back
Striated, voluntary, regularly arranged cells that contract in one direction, rapid contraction speed, short contraction length, muscle fibres are tubular and multinucleated
Card 3
Front
Cardiac Muscle
Back
Card 4
Front
Smooth Muscle
Back
Card 5
Front
In skeletal muscles, the bundles of muscle fibres are bound by a membrane, what is the membrane called?
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