KEY POINTS
1. All movement is the result of contraction of skeletal muscle across a movable joint.
2. There are several levels of organization in any skeletal muscle.
3. Action potentials on the sarcolemma spread to the interior of the cell along the transverse tubules.
4. The action potential on the sarcolemma is indirectly coupled to the contraction mechanism through the release of Ca2+ from the sarcoplasmic reticulum.
5. The sliding of actin along the myosin molecule results in physical shortening of the sarcomere.
6. Most skeletal muscle fibers can be classified as either fast-contracting or slow-contracting fibers.
7. Muscles change their strength of contraction by varying the number of active motor units or the rate of motor unit activation.
8. The electromyogram is the clinical measurement of the electrical behavior within a skeletal muscle.
9. The structure of cardiac and smooth muscle differs from that of skeletal muscle.
10. The role of Ca2+ ions in excitation-contraction coupling in cardiac and smooth muscle differs from that in skeletal muscle.