HN220 Lecture Notes - Lecture 5: Neuromuscular Junction, Myocyte, Multinucleate
Document Summary
Skeleton function: support body, provide articulation for body, bones function, support structures. Skeletal muscle: aka striated muscle, connected to bones by, tendons: strong bundles of collagen fibers, 2+ work together antagonistically, one contracts, one stretches, composed of: fibers: long, multinucleate cells innervated by motor nerves. A whole muscle is controlled by the firing of up to hundreds of motor axons. These motor nerves control movement in a variety of ways. One way the nervous system controls the amount of force being produced by a muscle is by adjusting the number of motor axons firing, thus controlling the number of twitching muscle fibers. A second way the nervous system controls a muscle contraction is to vary the frequency of action potentials in the motor axons. At stimulation frequencies of less than 5 hz, intracellular [ca2+] returns to normal levels between action potentials: the contraction consists of separate twitches.
