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The Muscular System

The Muscular System. Muscle tissue overview. All muscle cells are elongated, thus, all muscle cells, regardless of type, are called muscle fibers The ability of muscle to shorten or contract depends on 2 types of myofilaments Prefix: myo / mys : muscle Sarco : flesh. Muscle Types.

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The Muscular System

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  1. The Muscular System

  2. Muscle tissue overview • All muscle cells are elongated, thus, all muscle cells, regardless of type, are called muscle fibers • The ability of muscle to shorten or contract depends on 2 types of myofilaments • Prefix: • myo/mys: muscle • Sarco: flesh

  3. Muscle Types Muscle type: skeletal muscle cardiac muscle smooth muscle walls of hollow organs; Body location: attached to bone; walls of heart; single, very long cylindrical, multi- nucleate, striations; branching chains, uninucleate, striations; Single, spindles, uninucleate, no striations; Cell Shape: involuntary, ner- vous system controls, hormones, chemicals, stretch; involuntary, ner- vous system controls, hormones; Regulation of Contraction: voluntary, nervous system controls; Contraction Speed/Rhythmic: Slow/yes; Slow to fast/no; Very slow/some

  4. Skeletal Muscle • Key words: Skeletal, Striated, Voluntary

  5. Skeletal Muscle • Skeletal muscle fibers: are packed into the organs called skeletal muscles that attach to the body’s skeleton • Skeletal muscle fibers are cigar-shaped, multinucleate cells, and are the largest of the muscle fiber types • It is also known as striated muscle because its fibers appear to be striped • It is also known as voluntary muscle because it is the only muscle type subject to conscious control • Skeletal muscle tissue can contract rapidly and with great force, but it tires easily and must rest after short periods of activity

  6. Connective tissue wrapping • Each muscle fiber is enclosed in a delicate connective tissue sheath called an endomysium • A bundle of muscle fibers called a fascicleare surrounded by a connective tissue called the perimysium • A bundle of fascicles are surrounded by a connective tissue called the epimysium

  7. Tendons • The epimysia blend into the strong, cordlike tendons • Tendon connects muscle to bone • Tendons provide durability and conserve space

  8. Cardiac Muscles • Key words: Cardiac, striated, uninucleate, involuntary, heart

  9. Cardiac Muscle • Is found only in the heart • Cardiac muscle is like skeletal muscle in that it is striated and like smooth muscle in that it is involuntary and cannot be consciously controlled by most of us • Cardiac muscle fibers are branching cells joined by special junctions called intercalated disks

  10. Cardiac Muscle • The cardiac muscle is cushioned by small amounts of soft connective tissue and arranged in spiral or figure 8 bundles • Cardiac muscle usually contracts at a fairly steady rate set by the heart’s pacemaker, but can also be stimulated by the nervous system

  11. Smooth Muscle • Key words: smooth, visceral, involuntary, uninucleate, non-striated

  12. Smooth Muscle • Smooth muscle has no striations and is involuntary • Found in the walls of hollow visceral organs such as the stomach, urinary bladder etc.

  13. Smooth Muscle • Smooth muscle cells are arranged in 2 layers: • One layer runs circularly • The other running longitudinally • The two layers alternately contract and relax, and this changes the size and shape of the organ, resulting in the movement of food, wastes, etc.

  14. 4 Muscle Functions producing movement maintaining posture stabilizing joints generatingheat walking; swimming; move eyes; Smile  Frown  move fluid; move food. allow you to stand up straight against the force of gravity. help reinforce bones that do not articulate well with the skeleton; Ex.: shoulder ATP used to cause muscles to contract; ATP energy is lost as heat; This helps maintain body temperature.

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