Lesson 7.6Remember a muscle cellis called amuscle fiber
Muscles have threelayers ofwrappings:1. Endomysium –wraps an individualmuscle fiber
2.Perimysiumwraps manymuscle fibersforming bundlescalled fascicles
3. Epimysiumwraps thefasciles toform themuscle.
Thesewrappingstaper pastthe bellyand formthe tendon.
Structure of muscle cell1. Have many nuclei (skeletal)2. Many mitochondria3. Has endoplasmic reticulumcalled sarcoplasmic ...
Structure of muscle cell1. Have many nuclei (skeletal)2. Many mitochondria3. Has endoplasmic reticulum called sarcoplasmic...
Myofibrils:Run the length of the cellEach cell contains dozens tohundreds myofibrilsComposed of smaller unitscalled sar...
Muscle fiber/cell                Cell membraneNucleus               sarcomere
Sarcomere:Composed of overlapping proteinfibers    • myosin – a thick protein fiber    •actin – a thin protein fiberover...
Thick Myosinprotein filament    Thin Actin    protein    filament
How does a muscle contractNervous system sends amessage by the motorneuron to the muscle fibersstimulating them tocontract...
Neuromuscular junction – placewhere motor neuron and musclefiber meet (but don’t touch).Neurotransmitters – chemicalsthat ...
Muscle contraction control:oOne motor neuron branchesand controls a few tohundreds of muscle fibers.oMotor neuron called a...
Dexterity vs. strengthoDexterity - motor unitonly branches a few times.   ex. Your eyes when youread or thread a needle
Dexterity vs. strengthoDexterityoStrength - motor unit willbranch stimulating hundreds ofmuscle fibers at the same time.  ...
Biology Lesson7.6
Biology Lesson7.6
Biology Lesson7.6
Biology Lesson7.6
Biology Lesson7.6
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Biology Lesson7.6

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Biology Lesson7.6

  1. 1. Lesson 7.6Remember a muscle cellis called amuscle fiber
  2. 2. Muscles have threelayers ofwrappings:1. Endomysium –wraps an individualmuscle fiber
  3. 3. 2.Perimysiumwraps manymuscle fibersforming bundlescalled fascicles
  4. 4. 3. Epimysiumwraps thefasciles toform themuscle.
  5. 5. Thesewrappingstaper pastthe bellyand formthe tendon.
  6. 6. Structure of muscle cell1. Have many nuclei (skeletal)2. Many mitochondria3. Has endoplasmic reticulumcalled sarcoplasmic reticulum
  7. 7. Structure of muscle cell1. Have many nuclei (skeletal)2. Many mitochondria3. Has endoplasmic reticulum called sarcoplasmic reticulum4. Contains myofibrils which arethe contracting unit of the cell5. Has a Cell membrane
  8. 8. Myofibrils:Run the length of the cellEach cell contains dozens tohundreds myofibrilsComposed of smaller unitscalled sarcomeres
  9. 9. Muscle fiber/cell Cell membraneNucleus sarcomere
  10. 10. Sarcomere:Composed of overlapping proteinfibers • myosin – a thick protein fiber •actin – a thin protein fiberoverlapping of actin andmyosin makes muscle lookstriated
  11. 11. Thick Myosinprotein filament Thin Actin protein filament
  12. 12. How does a muscle contractNervous system sends amessage by the motorneuron to the muscle fibersstimulating them tocontract.(Note: nerve and muscle donot touch each other.)
  13. 13. Neuromuscular junction – placewhere motor neuron and musclefiber meet (but don’t touch).Neurotransmitters – chemicalsthat carry a nerve impulse acrossthe neuromuscular junctionstimulating myofibrils to contract.
  14. 14. Muscle contraction control:oOne motor neuron branchesand controls a few tohundreds of muscle fibers.oMotor neuron called a motorunit when branches andincludes the muscle fibers itconnects with.
  15. 15. Dexterity vs. strengthoDexterity - motor unitonly branches a few times. ex. Your eyes when youread or thread a needle
  16. 16. Dexterity vs. strengthoDexterityoStrength - motor unit willbranch stimulating hundreds ofmuscle fibers at the same time. ex. Lifting a heavy box

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