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Why is striated muscle often known as voluntary muscle or skeletal muscle?
It is under conscious control via the voluntary nervous sytem, and it is atached to the skeleton, enabling movements + locomotion.
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How is the connecting system between muscle and bone very strong?
- Muscles are attached to bones by non-elastic tendons made of bundles of white collagen fibres, which have high tensile strength
- Collagen fibres originate in collagen muscle sheaths of muscle tissue, run all through tendons and are continues as collagen fibres of actual bone
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What are the tendons of origin?
Attach the muscle to an immovable part of the skeleton, providing an anchor for muscle contraction.
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What are the tendons of origin?
Attach to the moveable bone, so when the muscle contracts the bone moves.
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State the difference in functions between ligaments and tendons.
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Explain muscle contraction in striated muscle.
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What does it mean when muscles are arranged in antagonistic pairs?
Biceps will flex at the elbow joint and it is antagonistic to triceps muscle which will extend the elbow joint.
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What is smooth muscle?
- Involuntary muscle that is regulated by the autonomic nervous system. Also called visceral muscle because sheets of it are found i nthe walls of the viscera like blood vessels, bladder, etc.
- Allows slow and sustained contractions
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What is cardiac muscle?
Makes up the bulk of the heart wall. It is myogenic, so initiates its own contractions, and has autorythmicity, so contracts/relaxes at a regular frequency (avg 72 BPM).
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What is the smallest contracting unit of skeletal muscle?
Sarcomere
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How are fibrils formed?
Sarcomeres arranged end to end to form long structures called fibrils.
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Distinguish between a fibril and a fibre in striated muscle.
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Why does skeletal muscle need a supply of creatine phosphate whereas smooth muscle does not?
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Why does skeletal muscle produce large quantitites of lactic acid whereas cardiac muscle does not?
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Describe the physiological events which occur during the latent period.
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Describe the physiological events which occur during the contraction period.
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Describe the physiological events which occur during the relaxation period.
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What are fast muscle fibres?
- Occur where the speed of response is more important than producing sustained contraction
- E.g. in external eye muscles in pectoral muscles of birds - white muscle
- There is less myoglobin + fewer mitochondria but the sarcoplasmic reticulum is very extensie to allow rapid release and uptake of Ca ions, allowing rapid contraction/relaxation.
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What are slow muscle fibres?
- Occur in limb muscles where contraction must be long enough to move a bone.
- Red muscle because it contains much red myoglobin, many mitochondria and a large capillary network
- Fibres can remain contracted for 0.3 seconds after impulse, longer than in white muscle.
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