Answer the following questions.1. list and describe the anatomical components that make up a muscle fiber. 2. list the components of a motor unit. 3. what are the steps in excitation–contraction coupling? 4. what is the role of calcium in muscle contraction? 5. describe the sliding filament theory. how do muscle fibers shorten? 6. what are the basic characteristics that differ between type i and type ii muscle fibers? 7. what is the role of genetics in determining the proportions of muscle fiber types and the potential for success in selected activities? 8. describe the relation between muscle force development and the recruitment of type i and type ii motor units. 9. explain, and give examples of, how concentric, static, and eccentric contractions differ. 10. what two mechanisms are used by the body to increase force production in a single muscle? 11. what is the optimal length of a muscle for maximal force development? 12. what is the relation between maximal force development and the speed of shortening (concentric) and lengthening (eccentric) contractions? 13. in muscle contraction, what roles are played by the protein titin? 14. why do previously trained muscles adapt more quickly to retraining after a period of disuse?