BIOL273 Lecture : Chapter 12 textbook material after midterm Exam review
16 Oct 2011
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Document Summary
Contraction of muscle fibres allows us to move or resist a load. Muscle tension force created by contracting muscle. Contraction creation of a tension in a muscle. Load weight or force that opposes contraction of muscle: active process that requires atp. Relaxation release of tension created by a contraction. Major steps leading to a muscle contraction: events are the neuromuscular junction. Convert ach signal from a somatic motor neuron into an electrical signal in the muscle fibre: excitation-contraction (e-c) coupling. Process in which muscle action potentials initiate calcium signals. In turn activate a contraction-relaxation cycle: molecular level contraction-relaxation cycle. Actin and myosin slide past each other during contraction. Rotation of myosin crossbridges provides the force that pushes the actin filament during contraction: myosin heads bind to actin molecules. Power stroke initiated by calcium signal: happens when myosin crossbridges swivel and push the actin filaments toward the center of the sarcomere, at the end the myosin head releases actin.
