Lab 6: Muscle Physiology
Abstract: Due to their attachment to the bones by tendons, skeletal muscles are used to produce movement and are also used for support. Skeletal muscles consist of many muscle fibers (muscle cells) that run the length of the muscle body. The muscle fibers are packed with many proteins, among them are the major contractile proteins, actin and myosin, which generate the force of a muscle contraction. Skeletal muscles are under voluntary control and are stimulated to contract by somatic motor neurons. A somatic motor neuron and the muscle fibers it innervates make up a motor unit. The response of a motor unit to stimulation is a muscle twitch. The size and speed of the twitch is affected by multiple factors including the size of the load on the muscle. The amount of force generated by a muscle depends on the number of motor units activated (recruitment) and the amount of force produced by the individual muscle fibers (for example, the summation of muscle twitches, which occurs with increased frequency of stimulation).