chapter nine

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Author:
dwatters
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74816
Filename:
chapter nine
Updated:
2011-03-23 18:02:19
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Skeletal Muscle
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Bio 100
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  1. The muscular system
    • * Muscles allow body movements
    • * Maintain posture
    • * Generate heat
    • * Three basic types
    • o Skeletal
    • o Smooth
    • o Cardio
  2. Skeletal muscle characteristics
    • * Are attached to bones
    • * Have striation (dark and light bands)
    • * Multinucleated
    • * Voluntary
    • * Stimulated consciously by the nervous system
  3. Anatomical appearance of skeletal muscle
    • * Muscles are separated by fibrous connective tissue called fascia
    • * Fascia forms a tendon
    • * Each skeletal muscle is considered an organ
  4. Anatomical appearance of skeletal muscle
    • * each organ is covered with a membrane called epimysium
    • * each muscle is made of many fascicles
    • * each fascicles is covered with a membrane called perimysium
  5. Anatomical appearance of skeletal muscle
    • * Each fascicle is made of many fibers (muscle cells)
    • * Each fiber is covered with a membrane called Endomysium
    • * Muscle fibers are made of proteins called Myofibrils
  6. Anatomical appearance of skeletal muscle
    • Sarcomer
    • * Sarcomer is the contractible unit of a muscle
    • * Striation has 2 parts: the I band (Light) and the A band (dark)
    • * I band is made of thin actin filaments
  7. Sarcomer
    • * A band is made of Thick filaments overlapping with thin filaments
    • * H zone consists of only Thick filaments
    • * M lines is made of proteins that help hold the thick filaments in place
    • * Z lines are made of proteins that attach the thin filaments
    • [actin makes up thin filaments]
  8. Muscle Fiber
    • * Muscle fiber have modified smooth endoplasmic reticulum called sacroplasmic reticulum, which stores calcium
    • * Transverse tubules are invaginations of the plasma membrane
  9. Muscle Fiber
    • * Skeletal muscle cells are voluntary and are stimulated by nerve cells
    • * The connection between a nerve cell and a muscle cell is called Neuromuscular junction
  10. Neuromuscular junction
    • * Small vesicles are found in the axon terminals
    • * These vesicles store signaling chemicals known as neurotransmitters
    • * The particular NT released on skeletal muscles is called acetylcholine
  11. Neuromuscular junction
    • * When the nerve cells send an electrical impulse, the neurotransmitters are released onto the membrane of the muscle fiber
    • * This causes the muscle fiber to contract
  12. Myofibril
    • * Myofibrils contain two major contractiles proteins called actin and myosin
    • * In addition, two other regulatory proteins called troponin and tropomyosin found on the thin filiments
    • * At rest actin has no physical contact with myosin
    • * When a muscle contracts myosin binds to actin
    • * This binding is known as power stroke
  13. What causes muscles to contract?
    • * Electrical stimulation is sent from nerve cells
    • * The nerve cells release the Neurotransmitter acetylcholine on the muscle cell
    • * The muscle cell becomes stimulated
    • * This causes the Smooth endoplasmic reticulum to release calcium
    • What is the function of calcium? Calcium facilitate the binding of the actin to myosin. ATP=energy
  14. Shortening of Sacomere
    * Muscle contraction is when the sacromere shortens in length
  15. Name two components the sliding filament theory depends on?
    • * ATP
    • * Calcium´┐Żsmooth endoplasmic reticulum
  16. Force Varies
    • * No matter what kind of force is needed
    • * When muscles contract, they require energy
    • * Where does energy come from?
    • * Mitochondria
  17. Mitchondria
    • * Elongated fluid filled sacs
    • * Double membrane
    • * Extensive folding of inner membrane
    • * Produce energy molecule (ATP)
  18. How is energy produced in the mitochondira?
    • * Energy production requires two major components:
    • * Macromolecules
    • o Come from food (carbohydrate, proteins, or fat)
    • * Oxygen
    • o Comes from the air around us
    • * When energy is made carbon dioxide is produced as waste product
  19. Why do our muscles get fatigue?
    • * Lack of energy molecule
    • * Oxygen debt
    • * Build-up of carbon dioxide
    • * Build-up of lactic acid

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