1. 1 C H A P T E R Muscle Physiology Gary R. Hunter

2. Chapter Outline  Skeletal muscle macrostructure and microstructure  Sliding-filament theory of muscular contraction  Fiber types  Types of muscle action  Force production

3. Three Types of Connective Tissue: Epimysium, Perimysium, and Endomysium

4. A Motor Unit

5. Sectional View of a Muscle Fiber

6. Detailed View of Myosin and Actin Protein Filaments in Muscle

7. T he discharge of an action potential from a motor nerve signals the release of calcium from the sarcoplasmic reticulum into the myofibril, causing tension development in muscle. 

8. Contraction of a Myofibril: Stretched Muscle

9. Contraction of a Myofibril: Partially Contracted Muscle

10. Contraction of a Myofibril: Completely Contracted Muscle

11. C alcium and ATP are necessary for myosin cross-bridge cycling with actin filaments. 

12. T ype II, or fast-twitch, muscle fibers are capable of developing higher forces than Type I, or slow-twitch, muscle fibers— especially at higher velocities of muscle action. 

13. T he number of cross-bridges that are attached to actin filaments at any instant in time dictates the force production of a muscle. 

14. Force-Velocity Curve for Eccentric and Concentric Actions

15. Three Arrangements of Muscle Fibers Fibers parallel to tendon Unipennate muscle Bipennate muscle

16. M any factors may affect rate of cross-bridge cycling and thus force, including neural activation, calcium concentration, myosin ATPase activity, preloading, prestretch, muscle fiber type and ultrastructure, fatigue through a variety of mechanisms, and number of contractile components (myosin and actin) in parallel. 