EXAM 2 (Key) - Solid Line = Action Potential Ventricular...

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Skeletal muscle fiber Solid Line = Action Potential Dashed Line = Tension Time (sec) Ventricular fiber Pacemaker cell EXAM 2 Biol 350: 10-28-2010 Name: Answer Key __________ ID: ______________________ 1. Name a cellular process and its associated physiological function that requires microtubules (2p each): Cellular process: transporting vesicles _________________ Physiological function: cell communication __________________ 2. The sarcomere is (circle 1, 2p) a. The membrane surrounding myofilaments b. Responsible for the striation seen in smooth muscles c. The basic contractile unit of skeletal muscle d. A region of mitochondria that supplies energy for contraction e. The calcium-containing store inside a muscle cell 3. According to the sliding-filament hypothesis of skeletal muscle contraction (circle 1, 2p) a. The length of the sarcomere at the beginning of stimulation does not affect the contraction force that is produced b. Contraction occurs due to the shortening of the thick filaments c. Contraction is caused by the action of calcium ions on the thick filament d. Muscles cannot shorten if the myofilaments are overlapping e. Cyclic binding and detachment of thick filament myosin crossbridges to actin filaments cause the sarcomere to shorten 4. The role of the transverse tubules (t-tubules) in the excitation of skeletal muscle contraction is to (circle 1, 2p) a. Serve as a store for calcium ions b. Provide an inward path for the spread of muscle action potentials c. Connect the sarcomeres d. Deliver ATP into the interior of the muscle cell e. Allow diffusion of oxygen to the mitochrondria of muscle fiber 5. The primary role of calcium in activation of contraction in striated muscles is to… (circle 1, 2p)
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a. Bind to the regulatory troponin complex to expose binding sites for myosin cross-bridges on actin molecules of thin filaments b. Cause a hyperpolarization of the muscle cell membrane c. Activate myosin molecules so that they can bind to actin d. Provide the energy necessary for a single contraction e. Regulate the removal of proteins from the muscle cell by exocytosis 6. Which of the following is a true statement about cardiac and skeletal muscles of vertebrates? (circle 1, 2p) a. The contractions of skeletal muscle are myogenic whereas those of cardiac muscle are neurogenic b. The action potentials of cardiac myocardial cells are much briefer than those of skeletal muscle c. Both skeletal muscle and cardiac muscle cells are dually innervated, receiving both excitatory and inhibitory inputs d. In both skeletal and cardiac muscle, troponin is the Ca 2+ binding protein that controls the contractile machinery e. Both, skeletal and cardiac muscle receive input from motor neurons to initiate contraction 7. Which of the following process is required for a muscle to be able to show rapid contraction and relaxation cycles? (CORRECT/FALSE) (circle 1, 2p) a. A very long refractory period of the muscle membrane b. A high number of cross-bridges that can be formed
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EXAM 2 (Key) - Solid Line = Action Potential Ventricular...

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