Exercise Physiology: Theory and Application to Fitness and Performance 9th Edition by Scott Powers, Edward Howley

Exercise 3

Tracing the path the action potential takes from the time it leaves the motor end plate, where might the “weak link” be in the mechanisms coupling excitation to contraction?

Step 1 of 3

The action potential follows the following path:

Brain ? spinal cord? peripheral nerve ? Muscle sarcolemma ? Transverse tubular system ? activation of Na+/K+ pump which causes excitation? release of Ca⁺⁺ from sarcoplamic ? Actin – myosin interaction ? Cross-bridge tension + heat ? force/power output.

When Ca⁺⁺ released from sarcolemma interacts with regulatory proteins like troponin, it results in movement of cross-bridges to create tension. Ca⁺⁺ must be pumped back after the force is generated, for the muscle to relax before another contraction.