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Which of these types of muscle cells are not capable of spontaneous depolarization?
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Human Physiology
- Which component is responsible for initially stimulating a muscle contraction? a. proteins b. electrochemical signals c. plasma membranes d. striationsarrow_forwardWhy do you think a person is able to perform anaerobic exercise (such as lifting and holding a heavy weight) only briefly but can sustain aerobic exercise (such as walking or swimming) for long periods? (Hint: Muscles have limited energy stores.)arrow_forwardSingle-unit smooth muscle cells can stimulate each other because they havea. a latch-bridge.b. diffuse junctions.c. gap junctions.d. tight junctions.e. cross-bridges.arrow_forward
- All of the following characteristics apply to skeletal muscle except a. They are striated. b. They are multinucleated. c. They are voluntary. d. They contain intercalated discs. e. They are attached to the skeleton by means of tendons.arrow_forwardWhich statement about striated skeletal muscle is true? A. The tension generated by a muscle is invariable. B. Mechanical summation of twitches in a muscle fiber leads to a graded increase in the tension that is above that generated by a single twitch. C. A single action potential arriving at the neuromuscular junction is not sufficient to cause a muscle fiber to twitch. D. Muscle twitches are able to mechanically sum when Ca2+ is quickly and completely removed from the sarcoplasm between action potentials. E. An action potential in the muscle cell activates contraction by releasing Na+ into the sarcoplasm.arrow_forwardSkeletal, smooth, and cardiac muscle are similar in that they all _____. A are divided into motor units B require calcium in order to contract C undergo mitosis frequently to replace dead or damaged cells D have small round cells connected by gap junctionsarrow_forward
- Which of the following statements about skeletal muscle is CORRECT? Select one: a. An increase in Na+ concentration in the cytosol starts muscle filament sliding. b. The muscle is non-striated and involuntary. c. The muscle is involved in shivering thermogenesis. d. The muscle contracts in response to parasympathetic stimulation. e. The muscle contracts in response to hormones.arrow_forwardmuscle cells are made up of? A. Z bars b. actin c. myosin d. myofibrilsarrow_forwardA skeletal muscle motor unit A.Is the number of muscle cells innervated by one motor neuron. B.Is the number of motor neurons innervating one muscle cell. C.Size determines the ability to control a muscle D.Size determines how much a muscle contracts at any one time.arrow_forward
- The muscles of a professional sprinter are most likely to have ________.a. 80 percent fast-twitch muscle fibers and 20 percent slow-twitch muscle fibersb. 20 percent fast-twitch muscle fibers and 80 percent slow-twitch muscle fibersc. 50 percent fast-twitch muscle fibers and 50 percent slow-twitch muscle fibersd. 40 percent fast-twitch muscle fibers and 60 percent slow-twitch muscle fibersarrow_forwardA bacterial toxin is known to block the release of ACh at the motor end plate of skeletal muscle. Consequently, a. the skeletal muscle contracts with increasing force. b. the skeletal muscle contracts with increasing frequency. c. the ability to stimulate the muscle is impaired. d. other neurotransmitters would stimulate the muscle.arrow_forwardWhich is a false statement about skeletal muscle structure?a. A myofibril is composed of multiple muscle fibers.b. Most skeletal muscles attach to bones by connective-tissue tendons.c. Each end of a thick filament is surrounded by six thin filaments.d. A cross-bridge is a portion of the myosin molecule.e. Thin filaments contain actin, tropomyosin, and troponin.arrow_forward
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