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Energy for Muscle Contraction

Energy for Muscle Contraction. Must have constant supply of ATP for contraction to be maintained. Creatine phosphate (CP) can also be used b/c of its high energy bond. Cellular respiration or catabolism of food generates more ATP or CP.

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Energy for Muscle Contraction

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  1. Energy for Muscle Contraction Must have constant supply of ATP for contraction to be maintained. Creatine phosphate (CP) can also be used b/c of its high energy bond. Cellular respiration or catabolism of food generates more ATP or CP. Some muscle fibers ensure an uninterrupted supply of glucose by storing it as glycogen.

  2. Providing Energy for Muscle Contraction Direct phosphorylation of ADP by reaction with creatine phosphate Energy Source: Oxygen Use: None 1 ATP per CP  Creatine and ATP are the products NRG supply lasts 15 sec CP

  3. Providing Energy for Muscle Contraction Anaerobic glycolysis and lactic acid formation Anaerobic- without oxygen 2 ATP Lactic acid accumulation (eventually reconverted to glucose in the liver) Heavy breathing helps to restore oxygen debt. Energy source is glucose No oxygen is used 2 ATP per glucose, lactic acid 30-60 sec. worth of energy

  4. Providing Energy for Muscle Contraction Aerobic Respiration/Oxidative Phosphorylation Aerobic- with oxygen 36-38 ATP Myoglobin pigment in muscles holds oxygen when muscles are at rest (muscles with much myoglobin are called red fibers; white fibers do not have much myoglobin).

  5. Energy Systems used during contraction

  6. VI. All-or-none Priciple Muscle cells do not partially contract. They either do or they do not. The minimum level of stimulation required to cause a fiber to contract is the threshold stimulus.

  7. Muscle Twitch Response of a muscle to a single brief threshold • Latent Period: few ms between stim. & contrac. coupling • Contraction: cross-bridges active • Relaxation: begins with Ca2+ moving into SR

  8. Wave summation • Muscle responds to the frequency and strength of simulation

  9. Muscle Contractions • Isotonic: Moving montraction

  10. Muscle Contraction • Isometric: Myofilaments are skidding instead of sliding and the tension in the muscle keeps increasing

  11. Exercise • Endurance: Aerobic • Stronger, flexible muscles • Greater resistance to fatigue • Increase in blood supply • Fibers form more mitochondria • Store more oxygen

  12. Exercise • Resistance or Isometric Exercise • Increased muscle size • Increase strength • Enlargement of individual fibers • More mitochondria

  13. Muscle Fatigue and Oxygen Debt • Muscle fatigue: unable to contract • May result from oxygen debt • Oxygen Debt must be paid back • Rapid breathing: continues until the amount of oxygen needed to get rid of the accumulated lactic acid by making ATP and creatine reserves

  14. Before a skeletal muscle fiber can contract, it has to receive an impulse from a nerve cell. Generally, an artery and at least one vein accompany each nerve that penetrates the epimysium of a skeletal muscle. Branches of the nerve and blood vessels follow the connective tissue components of the muscle of a nerve cell and with one or more minute blood vessels called capillaries.

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