Muscle Contraction Test With Questions and Answers

Muscle Contraction Test With Questions and Answers What happens to the A band during muscle contraction? - ANSWER it stays the same What happens to the I band during muscle contraction? - ANSWER it shorten s What happens to the H band during muscle contraction? - ANSWER it shortens and disappears What happens to the sarcomere during muscle contraction? - ANSWER it shortens What happens to the A band during muscle relaxation? - ANSWER it stays the same What happens to the H band during muscle relaxation? - ANSWER it lengthens What happens to the I band during muscle relaxation? - ANSWER it length ens What happens to the sarcomere during muscle relaxation? - ANSWER it lengthens What is the first step of muscle contraction? - ANSWER acetylcholine released from lower motor neurons, binds to ligand-gated sodium channels (nicotin ic receptors located on the postsynaptic membrane, specifically the motor end pl ate), causing sodium influx/depolarization and massive EPSP What is the second step of muscle contraction? - ANSWER due to the occurrences in the first step, action potential is triggered across the entire skelet al muscle membrane (sarcolema) What is the third step of muscle contraction? - ANSWER action potential travel s down t-tubules, which are adjacent to terminal cisternae; causes the r elease of Ca from cisternae; Ca then binds to troponin, causing shape change and because troponin is attached to tropomyosin, the shape change causes displacement of trypomyosin, revealing binding sites on the actin What is the fourth step of muscle contraction? - ANSWER myosin heads bind to