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What are the 3 types of muscle tissue in the body?
- cardiac
- skeletal (striated, voluntary)
- smooth (visceral, involuntary)
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Skeletal muscle
- aka "voluntary", "striated"
- contractions are voluntarily controlled
- 40 - 50% of body weight
- threadlike and cylindrical; appear in bundles
- composed of striated muscle cells and connective tissue
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Cardiac muscle
- composes the bulk of the heartintercalated disks cause the heart to contract as one uint
- muscle cells branch frequently
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Smooth muscle
- aka "nonstriated", "involuntary", "visceral"
- no cross stripes or striations
- tapered at each end
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Parts of the skeletal muscle
- origin: attaches to the stationary bone of a joint
- insertion: attaches to the movable bone of a joint
- body: main part of the muscle
i.e. the top of the bicep is the origin; the bottom is the insertion
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Tendons
- fibrous connective tissue that anchors muscles to bones
- some are enclosed in synovial lined tubes called tendon sheaths
- lubricated by synovial fluid
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Bursae
- small synovial lined sacs containing synovial fluid
- a slippery cushion
- found between tendons and the bones beneath them
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Muscle fiber
- made of thick and thin myofilaments
- thick myofilaments: myosin
- thin myofilaments: actin
- when muscles contract, actin and myosin connect to form cross bridges
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sarcomere
- basic contractile (functional) unit of skeletal muscle
- seperated from each other by dark bands called z lines
- made of mulitiple actin and myosin filaments
- when muscles contract, actin and myosin come together and shorten the sarcomere and thus the entire muscle
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