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Muscles

Muscles. What are muscles?. The “engine” that your body uses to propel itself. Turn energy (ATP) into motion. Needed for communication Long lasting, self-healing, and able to grow stronger. 40% of your body weight. Over 630 muscles involved in movement. Types of Muscles.

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Muscles

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  1. Muscles

  2. What are muscles? • The “engine” that your body uses to propel itself. • Turn energy (ATP) into motion. • Needed for communication • Long lasting, self-healing, and able to grow stronger. • 40% of your body weight. • Over 630 muscles involved in movement.

  3. Types of Muscles • Skeletal- can see and feel -attached to the bones • Smooth-found in digestive system, stomach and intestines, blood vessels, and airways. • Cardiac- heart muscle

  4. Muscle Movement • Your brain sends a chemical signal down a nerve cell. • Fibers (Myofilaments, Striations) flex, or extend • Voluntary Movement-skeletal • Involuntary Movement-smooth and cardiac • Over 630 muscles used in movement

  5. Fun Facts • Over 30 facial muscles that create looks of surprise, happiness, sadness • Eye muscle busiest-100,000X a day • Gluteus maximus is the biggest muscle

  6. Skeletal Muscle • Endomysium • Connective tissue surrounding each individual fiber • Fascicles • Fibers are grouped together in bundles • Perimysium • Separates each fascicle • Epimysium • The whole muscle is surrounded by this connective tissue layer

  7. Skeletal Muscle

  8. Muscle Fiber • Sarcolemma • The plasma membrane of each fiber • Has infoldings called Transverse Tubules that penetrate each fiber • Myofibrils • 1 µm in diameter • Contained within the fibers cytoplasm called sarcoplasm • Myofilaments • Bundle of parallel microfilaments within each myofibril

  9. Myofilaments • The key to muscle contraction is the arrangement of the myofilaments • Two kinds • Thick filaments- 11nm in diameter, myosin • Thin filaments- actin, 5 to 6 nm in diameter, • tropomyosin • troponin

  10. Myofilaments

  11. Striations • A-bands • Dark, thick filaments surrounded by thin filaments • H-band • Lighter portion in the middle of the A-band where thin filaments do not reach • I-bands • Light band composed of thin filaments only • Z-disc • Dark narrow line that bisects each I-band • This is the functional contractile unit of the muscle fiber

  12. Striations

  13. Fueling Muscle Contraction • ATP is the immediate source of energy for muscle contraction. Although a muscle fiber contains only enough ATP to power a few twitches, its ATP "pool" is replenished as needed. There are three sources of high-energy phosphate to keep the ATP pool filled...

  14. ATP Sources • Creatine Phosphate • Glycolysis of Glycogen • Cellular Respiration

  15. Creatine Phosphate

  16. Glycolysis Glucose + 2 ADP + 2 Pi + 2 NAD+---> 2 Pyruvate + 2 ATP + 2 NADH + 2 H+ + 2 H2O

  17. Cellular Respiration

  18. Muscular DevelopmentHormonal Response to Resistance Training (hypertrophy) • Testosterone (C19H28O2) • Steroid Hormone • Growth Hormone (hGH)

  19. Testosterone • Initiates sperm production and development of male secondary characteristics • Females produce 1/10th of males • Anabolic, Tissue-building role • Interacts with neural receptors • Initiates structural protein changes that alter size of neuromuscular junction • Promotes GH release

  20. Growth Hormone (Somatotropin) • Increases protein synthesis • Stimulates liver production of IGFs (somatomedins) • How exercise stimulates GH release remains unclear. • GH works through second messenger system (cyclic AMP)

  21. References • www.howstuffworks.com • http://www.med.unibs.it/~marchesi/muscle.html • Exercise Physiology, 5th edition, William D. McArdle: 2001.

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