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31 Cards in this Set
- Front
- Back
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skeletal muscle
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attaches to skeleton, provides strength and mobility, voluntary control
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cardiac muscle
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allows heart to pump blood; involuntary control
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smooth muscle
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lines walls of hollow organs; involuntary control
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all three muscle types share this characteristic
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all excitable tissues (activated by chemical/ electrical signals)
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all muscles have one basic mechanism of action
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contract (shorten) and relax (lengthen)
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function of muscle
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produce/resist movement, generate heat
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what two points attach skeletal muscle to skeleton?
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origin and insertion
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origin
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remains fairly stationary
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insertion
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attaches to different bone so muscle/tendon crosses a joint
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how does movement relate to insertion and origin?
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movement produced as insertion is pulled towards the origin
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muscles classified into 2 functional groups when describing motion
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agonists and antagonists
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agonists
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main movers; responisble for most of movement
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antagonists
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oppose the action of the main movers
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contraction of biceps
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forearm (elbow) flexion
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concentric contraction
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muscle shortens
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isometric contraction
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muscle maintains constant length (static)
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eccentric contraction
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muscle lengthens
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isotonic contraction
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load/force remains constant
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whole muscle
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made up of many individual muscle cells or muscle fibers
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fascicles
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bundles in which whole muscle is arranged. each may have only a few muscle fibers or many thousands of muscle fibers
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fascia
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sheath of connective tissue that encloses each fascicle. covers outer surface of muscle too.
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where do fasciae converge?
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at ends of muscle to form tendon which attaches muscle to bone
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muscle fibers
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tube shaped cells, larger and longer than most other cell types, contains many nuclei located under cell membrane
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myofibrils
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long cylindrical structures arranged parallel, contain proteins actin and myosin, as each individual one contracts so does muscle fiber and so does whole muscle. striated appearance.
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sarcomeres
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make up myofibril, give myofibril striated appearance. functional unit of contraction. each has z-line at each end and can be several hundred thousand per myofibril.
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i-band
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light, actin only
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a-band
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dark, myosin (actin overlaps at outer edges)
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h-zone
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center of a-band, only when relaxed
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m-line or m-region
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center of a-band, where myosin filaments are held together
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z-line
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center of i-band
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during muscle contraction, does each individual sarcomere within a muscle fiber shorten at the same time or at various times?
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same time
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