Exam 1 - HK 100 Questions and Answers Graded A+

Exam 1 - HK 100 motor unit - Answer- A motor neuron and all of the nerve and muscle fibers it innervates; controls muscle fibers within a muscle sacromere - Answer- Basic contracting unit of muscle cell consists of actin and myosin filaments between z-lines in a muscle cell delayed onset muscle soreness - Answer- Pain or discomfort often felt 24 to 72 hours after intense exercise or unaccustomed physical activity (DOMS) concentric - Answer- when muscle fibers are shortening (Ceiling)(flexion) eccentric - Answer- when muscle fibers lengthen (Earth)(extension) isometric - Answer- when muscle fibers tense (tension) but no actual movement (In between) sliding filament hypothesis - Answer- thin filaments slide over thick filaments, shortening the sarcomere cross-bridge hypothesis - Answer- muscle contraction states how force is produced, and how the filaments actin and myosin are moved relative to each other to produce muscle shortening Electromyography (EMG) - Answer- the electrical recording of muscle activity myosin - Answer- thick filament (in A-band) actin - Answer- thin filaments first step of muscle contraction - Answer- in the neuromuscular junction, a chemical is released from the end of the nerve fiber, which causes a rapid change in voltage in the muscle second step of muscle contraction - Answer- the electrical signal travels over the surface of, and along, the muscle fibers third step of muscle contraction - Answer- the electrical signal causes the release of calcium ions into the cytoplasm (intracellular fluid( of the muscle fiber. this i san important part of the process because it is the line between excitation and contraction) fourth step of muscle contraction - Answer- the calcium ions expose active sites on the actin (thin) myofilaments, to which the myosin filaments immediately attach final step of muscle contraction - Answer- because of these attachments (cross-bridges), each myosin filament pulls the actin filaments that overla