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An isotonic contraction is described as Select one: a. action potential frequency is high enough that no relaxation of muscle fibers occurs. b. a muscle produces constant tension during contraction. c. a muscle produces an increasing tension during contraction. d. a muscle produces increasing tension as it shortens. e. a muscle produces tension, but the length of the muscle is increasing - ✔✔b. a muscle produces constant tension during contraction.
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An isotonic contraction is described as Select one: a. action potential frequency is high enough that no relaxation of muscle fibers occurs. b. a muscle produces constant tension during contraction. c. a muscle produces an increasing tension during contraction. d. a muscle produces increasing tension as it shortens. e. a muscle produces tension, but the length of the muscle is increasing - ✔✔b. a muscle produces constant tension during contraction. After contraction has occurred, the calcium is Select one:
a. destroyed by cholinesterase. b. chemically bound to the cross bridges. c. secreted by the Golgi apparatus to the outside of the cell. d. released from troponin. e. returned to the sarcolemma. - ✔✔d. released from troponin. Increased strength of a trained muscle is due to Select one: a. an increased number of muscle fibers. b. the nervous system's ability to recruit a large number of motor units simultaneously. c. elimination of unnecessary enzymes and metabolic pathways. d. elimination of all fat deposits.
a. breaks down glycogen b. synthesizes ATP c. acts as a reservoir for oxygen d. produces action potentials e. stores glucose - ✔✔c. acts as a reservoir for oxygen The outside of the resting plasma membrane is relative to the inside of the resting plasma membrane. Select one: a. positively charged b. negatively charged c. electrically neutral d. recharged e. None of these choices is correct. - ✔✔a. positively charged
Fascia Select one: a. surrounds individual muscles. b. separates muscle fibers. c. connects muscles to bone. d. is a type of muscle tissue. e. is a type of nerve tissue. - ✔✔a. surrounds individual muscles. When repolarization of the cell membrane is complete, the Select one: a. cell dies. b. cell regenerates.
Select one: a. can rapidly develop action potentials b. shallow invaginations of cell membrane c. relatively constant tension maintained for a period of time d. intracellular cytoskeleton e. enzyme that removes phosphate from myosin - ✔✔c. relatively constant tension maintained for a period of time 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 Select one: a. neuromuscular junctions. b. sarcomeres. c. myofilaments.
d. Z disks. e. cell body of neuron. - ✔✔a. neuromuscular junctions. List the following structures in order from smallest to largest. (1) muscle fiber (2) myofilament (3) myofibril (4) muscle fasciculus Select one: a. 4, 2, 3, 1 b. 2, 1, 4, 3 c. 3, 1, 4, 2 d. 2, 3, 1, 4
b. forms the cross-bridge. c. removes phosphate from myosin. d. binds to calcium-calmodulin complex. e. opens calcium channels. - ✔✔c. removes phosphate from myosin. Which type of muscle tissue would cause flexion and extension of the arm? Select one: a. skeletal muscle b. smooth muscle c. cardiac muscle - ✔✔a. skeletal muscle An isometric contraction is described as Select one:
a. action potential frequency is high enough that no relaxation of muscle fibers occurs. b. a muscle produces constant tension during contraction. c. a muscle produces an increasing tension as the length remains constant. d. a muscle produces increasing tension as it shortens. e. a muscle produces tension, but the length of the muscle is increasing. - ✔✔c. a muscle produces an increasing tension as the length remains constant. Which of the following causes an unequal ion concentration across the resting plasma membrane? Select one: a. the functioning of the sodium-chloride pump b. negatively charged proteins do not readily diffuse across the plasma membrane c. the attraction of chloride ions to other intracellular anions d. the repulsion of potassium ions by the intracellular anions
a. is raised by sweating. b. results from the heat produced when muscles contract. c. will increase after blood vessels in the skin constrict. d. is lowered by shivering. e. decreases when the rate of the chemical reactions increase. - ✔✔b. results from the heat produced when muscles contract. Visceral smooth muscle Select one: a. may contain groups of cells that function as an independent unit. b. occurs in sheets and exhibits numerous gap junctions. c. contracts only when stimulated. d. does not function as a unit. e. All of these choices are correct. - ✔✔b. occurs in sheets and exhibits numerous gap junctions.
Which of these is true of skeletal muscle? A) spindle-shaped cells B) under involuntary control C) many peripherally located nuclei per muscle cell D) forms the walls of hollow internal organs E) may be autorhythmic - ✔✔C) many peripherally located nuclei per muscle cell Which of these is not a major functional characteristic of muscle? A) contractility B) elasticity C) excitability D) extensibility E) secretability - ✔✔E) secretability
Each myofibril A) is made up of many muscle fibers. B) contains sarcoplasmic reticulum. C) is made up of many sarcomeres. D) contains T tubules. E) is the same thing as a muscle fiber. - ✔✔E) is the same thing as a muscle fiber. Myosin myofilaments are A) attached to the Z disk.
B) found primarily in the I band. C) thinner than actin myofilaments. D) absent from the H zone. E) attached to filaments that form the M line. - ✔✔E) attached to filaments that form the M line. Which of these statements about the molecular structure of myofilaments is true? A) Tropomyosin has a binding site for Ca2+. B) The head of the myosin molecule binds to an active site on G actin. C) ATPase is found on troponin. D) Troponin binds to the rodlike portion of myosin. E) Actin molecules have a hingelike portion that bends and straightens during contraction. - ✔✔B) The head of the myosin molecule binds to an active site on G actin.
During depolarization, the inside of the membrane A) becomes more negative than the outside of the membrane. B) becomes more positive than the outside of the membrane. C) is unchanged. - ✔✔B) becomes more positive than the outside of the membrane. During repolarization of the plasma membrane, A) Na+ move to the inside of the cell. B) Na+ move to the outside of the cell. C) K+ move to the inside of the cell. D) K+ move to the outside of the cell. - ✔✔D) K+ move to the outside of the cell. Given these events: