BIOL 2404 Chapter Notes - Chapter 8: Resting Potential, Neuromuscular Junction, Skeletal Muscle
Document Summary
Functions of the muscular system: body movement (skeletal muscle, maintenance of posture (skeletal muscle, respiration (skeletal muscle, production of body heat (skeletal muscle, communication (skeletal muscle, constriction of organs and vessels (smooth muscle, heartbeat (cardiac muscle) Functional characteristics of muscle: contractility: the ability to shorten forcibly, excitability: the ability to receive and respond to stimuli, extensibility: the ability to be stretched or extended, elasticity: the ability to recoil and resume the original resting length. Myofilaments do not change length during muscle contraction: during contraction, actin myofilaments at each end of the sarcomere slide past the myosin myofilaments toward each other. As a result, the z disks are brought closer together, and the sarcomere shortens: as the actin myofilaments slide over the myosin myofilaments, the h zones (yellow) and the i bands (blue) narrow. The a bands, which are equal to the length of the myosin myofilaments, do not narrow because the length of the myosin myofilaments does not change.
