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Muscle Contraction and Energy Sources

Learn about the physiology of muscles, including contraction types, energy sources, and the process of relaxation. Includes diagrams and assignments.

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Muscle Contraction and Energy Sources

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  1. Review questions Review contraction Notes Relaxation Energy sources Isometric and isotonic contractions Contraction graphs Do, or do not do. There is no ‘try’. Yoda To learn about the physiology of muscles. Title: Anat & Phys 11/30/06 Class Topics Objectives: Friday, December 20, 20199:55 AM

  2. Class Assignments What By When • Read 197-212 12/4/06 • Muscle Physiology quiz 12/4/06 • Contraction assignment 12/4/06 • Muscle physiology test 12/8/06 • Due this class period • Due next class period • Due in the future

  3. Review • Sketch a myofibril • Label A band, I band, Z line, H zone, sarcomere, actin, myosin • What is the purpose for nuclei in the muscle cell? • What is the purpose for mitochondria in the muscle cell? • What connective tissue covering is found surrounding each fascicle? • What are three proteins are found in the “thin filament”? • What is a 1:10 ratio of motor neurons to muscle cells used for? What muscles?

  4. Muscle physiology quiz • Topics • Organelles • All or none principle • Myofibril anatomy • Neuromuscular junction • Connective tissue coverings • Innervation ratios

  5. Contraction step by step • Stimulation - acetylcholine released from motor neuron • Muscle fiber stimulation by acetylcholine & calcium ions are released from the sarcoplasmic reticulum • Calcium ions bind to troponin molecule • Troponin molecules change shape causing tropomyosin to rotate and expose active sites on the actin molecule

  6. Contraction step by step • Cross bridges form between actin (active sites) and myosin filaments (globular proteins) • Actin filaments slide along myosin filaments (ATP used) due to a swivel action of myosin globular protein • Muscle fiber shortens as contraction occurs Wisconsin Online - animation Texas A&M University - animation

  7. Relaxation • Acetylcholine decomposes and muscle fiber is no longer stimulated • Calcium ions are Actively TransPorted into sarcoplasmic reticulum • Cross bridges between actin and myosin are broken – troponin is no longer activated and it (and tropomyosin) rotates back into resting position over actin active sites

  8. Relaxation (cont.) • Actin and myosin slide apart • Muscle fiber lengthens and resting state is reestablished

  9. Pattern Puzzle • Put the paragraph on contraction back together

  10. From: http://biomedia.bio.purdue.edu/GenBioLM/ GBMuscle/html/myofilaments.html

  11. Assignment • In a series (at least 7) of pictures, draw a representation of contraction and relaxation. • Include a written basic overview of what is occurring in each step. • 10 pts. “Don’t tell people how to do things. Tell them what to do and let them surprise you with their results.” George Patton

  12. Energy Sources for Contraction • ATP - found on each globular protein of myosin - 1 or 2 contractions • Creatine phosphate - 25 secs. - changes ADP into ATP so the body can use it for energy • Other sources

  13. Other Sources of NRG • Cellular respiration - using stored glucose and oxygen to form ATP • very efficient • Anaerobic Respiration • no oxygen • changes glucose to pyruvic acid and then to lactic acid - discomfort in muscles • inefficient energy source

  14. From: http://www.nismat.org/physcor/energy_supply.html

  15. Anaerobic Respiration • Oxygen debt • oxygen goes toward decomposition of lactic acid - not respiration • Muscle fatigue • too much lactic acid - low pH - no contraction • Muscle cramp • muscle contracts but doesn’t relax • not enough ATP to move calcium ions back into SR

  16. Muscle Tone • Sustained contraction occurring in muscle fibers at all times - resting muscle • Used for posture, body positioning, reflexes, and keep body firm • Lost when a person passes out • dead weight

  17. Athletes • Higher tolerance to lactic acid • more capillaries in muscles • More muscle tone

  18. Contraction types • Tetanic contractions • sustained contraction produced by rapid sequence of stimuli • Types of tetanus • 1. Isotonic • 2. Isometric

  19. Isotonic • Produces movement as the muscle pulls the bone toward a stationary structure • ex. Bicep curl • All movements!

  20. Isometric • Produces muscle tensions, but the muscle does not shorten • No body movement • ex. Pushing an immovable object

  21. Twitch

  22. Muscle TypesHO “Muscle, Genes, and Athletic Performance” • Slow twitch • Type I • Fast twitch • Type IIe • Type IIx

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