Bio 264 Exam 3 Questions With Complete Solution

Bio 264 Exam 3 Questions With Complete Solution What structure runs from Z line to Z line? - CORRECT ANSWER Sarcomere The movement of the troponin-tropomyosin complex requires _______ - CORRECT ANSWER Ca2+. The actin filament is a polymer formed from 300 to 400 globular subunits called ______ - CORRECT ANSWER G-actin. A myofilament is the _________. - CORRECT ANSWER Protein strand composed of actin or myosin T tubules ________. - CORRECT ANSWER Conduct action potentials deep into the muscle cell A drug that interferes with the active transport of calcium ions from the sarcoplasm back into the sarcoplasmic reticulum would result in _______. - CORRECT ANSWER Contraction with no relaxation Cardiac muscle cells are like skeletal muscle cells in that they both ________. - CORRECT ANSWER have striations Predict the consequences of administration of a compound that blocks the calcium channels on presynaptic motor neuron terminals. A. This should ultimately inhibit the release of acetylcholine B. This should ultimately inhibit the muscle membrane from depolarization C. This should ultimately inhibit the release of calcium from the sarcoplasmic reticulum D. All of the above are correct answers - CORRECT ANSWER D. All of the above are correct answers Predict the consequences of administration of a compound that inhibits acetylcholinesteras - CORRECT ANSWER The muscle will stay contracted Myofibrils are composed primarily of ________. - CORRECT ANSWER Actin and myosin Binding of ________ to myosin permits cross-bridge _____________ between actin and myosin. - CORRECT ANSWER ATP; detachment The part of the sarcolemma that invaginates into the interior of skeletal muscle fibers is the - CORRECT ANSWER T tubule system. Somatic motor neurons release the neurotransmitter _________ at the neuromuscular junction. - CORRECT ANSWER Acetylcholine The gangster movies call a dead person a stiff, rigor mortis is the proper name. How does this occur? - CORRECT ANSWER Without ATP, muscles remain fixed in their last state of contraction. T tubules are invaginations of the ________. - CORRECT ANSWER Sarcolemma One cause of spastic paralysis might be ________. - CORRECT ANSWER Inhibition of acetylcholinesterase Somatic motor neurons release the neurotransmitter _________ at the myoneural junction. - CORRECT ANSWER Acetylcholine Rigor mortis occurs after death because - CORRECT ANSWER Cross-bridges form but can't release. Given these events: (1) Acetylcholine is broken down into acetic acid and choline. (2) Acetylcholine diffuses across the synaptic cleft. (3) An action potential reaches the terminal branch of the motor neuron. (4) Acetylcholine combines with a ligand-gated ion channel. (5) An action potential is produced on the muscle fiber's plasma membrane. Choose the arrangement that lists the events in the order they occur at a neuromuscular junction. - CORRECT ANSWER 3,2,4,5,1 The sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called ________. - CORRECT ANSWER Neuromuscular junctions Acetylcholine is released from the presynaptic terminal by the process of _________. - CORRECT ANSWER Exocytosis Arrange the following list of biochemical events in the correct sequence. 1.An action potential is conducted deep into the muscle fiber by the T tubule. 2.Calcium ions bind to troponin. 3.The membranes of the sarcoplasmic reticulum become more permeable to calcium ions. 4.Calcium ions diffuse into the sarcoplasm around the myofibril. 5.The troponin-tropomyosin complex moves exposing active sites. - CORRECT ANSWER 1, 3, 4, 2, 5 Curare blocks acetylcholine receptors at the motor end plate. This would result in _______. - CORRECT ANSWER Inability of the muscle fiber to respond to nervous stimulation Subunits of skeletal muscle cells that are composed of sarcomeres are called - CORRECT ANSWER Myofibrils. In excitation-contraction coupling, _________. - CORRECT ANSWER Myosin heads bind to exposed active sites on actin Predict the consequences of administration of a compound that binds to acetylcholine receptors in a neuromuscular junction but does not open them. - CORRECT ANSWER The muscle membrane will not reach threshold Given these events: (1) sarcoplasmic reticulum releases Ca2+ (2) sarcoplasmic reticulum takes up Ca2+ (3) Ca2+ diffuse into myofibrils (4) action potential moves down the T tubule (5) sarcomere shortens (6) muscle relaxes Choose the arrangement that lists the events in the order they occur following a single stimulation of a skeletal muscle cell. - CORRECT ANSWER 4,1,3,5,2,6 The sarcolemma is the _________. - CORRECT ANSWER Cell membrane of a muscle fiber What is a cross-bridge? - CORRECT ANSWER The combination of myosin heads with active sites on actin molecules