Human Physiology From Cells To Systems 3rd Edition by Lauralee Sherwood – Test Bank A+

$35.00
Human Physiology From Cells To Systems 3rd Edition by Lauralee Sherwood – Test Bank A+

Human Physiology From Cells To Systems 3rd Edition by Lauralee Sherwood – Test Bank A+

$35.00
Human Physiology From Cells To Systems 3rd Edition by Lauralee Sherwood – Test Bank A+
A skeletal muscle undergoes hypertrophy mainly by producing many more muscle fibres.

a.True
b.False

2. Foot proteins link the actin molecules together within a thin filament.

a.True
b.False

3. A single muscle cell is known as a myofibril.

a.True
b.False

4. The metabolic capability of a muscle fibre can affect the degree of tension it can develop.

a.True
b.False

5. The strength and rate of contraction of the heart can be influenced by the autonomic nervous system.

a.True
b.False

6. The two types of fast twitch fibres are interconvertible depending on the type of conditioning they receive.

a.True
b.False

7. Cross bridges have actin binding sites that are normally covered by troponin and tropomyosin, except during excitation–contraction coupling.

a.True
b.False

8. Thin and thick filaments overlap in the A band.

a.True
b.False

9. The corticospinal system controls fine, discrete, voluntary body movements.

a.True
b.False

10. According to the sliding filament mechanism of muscle contraction, the muscle fibres of one motor unit slide in closer together between the muscle fibres of adjacent motor units.

a.True
b.False

11. Rigor mortis occurs when Ca2+ links actin and the myosin globular head together in a rigor complex.

a.True
b.False

12. Fast-glycolytic muscle fibres do not require as much oxygen use as slow-oxidative fibres.

a.True
b.False

13. In an isotonic contraction, only 25 percent of the energy consumed is realized as external work, and the remaining 75 percent is converted to heat.

a.True
b.False

14. The actin filaments in sarcomere contain cross bridges.

a.True
b.False

15. During the power stroke, all the cross bridges on myosin do not stroke in unison when pulling the actin filaments.

a.True
b.False

16. Joints serve as fulcrums for muscle action.

a.True
b.False

17. Tropomyosin covers the cross-bridge binding sites on the thick filaments when a sarcomere is not contracting.

a.True
b.False

18. The contraction phase of a muscle cell lasts longer than the relaxation phase.

a.True
b.False

19. Oxidative phosphorylation occurs within the mitochondria of muscle cells.

a.True
b.False

20. Myosin has ATPase activity.

a.True
b.False

21. Oxygen debt is the oxygen a skeletal muscle produces or pays off when it carries out glycolysis.

a.True
b.False

22. Muscles that have a fine degree of control have small motor units.

a.True
b.False

23. Myosin is considered to be a regulatory protein because it plays an important role in the regulation of muscle contraction.

a.True
b.False

24. Tetanus occurs when a muscle fibre is stimulated so rapidly that it is not allowed to relax between stimulations, resulting in a smooth, sustained contraction.

a.True
b.False

25. Skeletal muscles are capable of limited repair after injury.

a.True
b.False

26. All muscle-lever systems work at a mechanical disadvantage.

a.True
b.False

27. Gradation of muscle contraction can be accomplished by stimulating variable portions of each motor unit.

a.True
b.False

28. Increasing the number of recruited motor units in a muscle increases its force or strength of contraction.

a.True
b.False

29. Both multiunit and single-unit smooth muscles are under motor control from the autonomic nervous system.

a.True
b.False

30. More tension is developed during twitch summation than during a single twitch because the duration of elevated cytosolic Ca2+ concentration increases during summation, thus increasing the availability of cross-bridge binding sites.

a.True
b.False

31. The M line is formed by a flattened disc-like cytoskeletal protein that connects the thin filaments of two adjoining sarcomeres.

a.True
b.False

32. Fast-oxidative muscle fibres have a high concentration of mitochondria.

a.True
b.False

33. During muscle contraction, the A band becomes shorter.

a.True
b.False

34. Single-unit smooth muscle and cardiac muscle are both self-excitable.

a.True
b.False

35. ATP expenditure is required for both contraction and relaxation of a muscle fibre.

a.True
b.False

36. Acetylcholinesterase removes ACh from receptors.

a.True
b.False

37. Single-unit smooth muscle has no innervation.

a.True
b.False

38. The skeletal muscle shortens during concentric, isotonic contraction.

a.True
b.False

39. According to the sliding filament mechanism of muscle contraction, the thick filaments slide in closer together to shorten the sarcomere.

a.True
b.False

40. Ligaments attach muscles to bones.

a.True
b.False

41. The lever system at the elbow joint provides a mechanical advantage so that, when the biceps muscle contracts to flex the elbow joint and lift an object in the hand, the force developed in the biceps can be considerably less than the actual load that is moved.

a.True
b.False

42. Summation events result from increasing amounts of cytoplasmic calcium levels.

a.True
b.False

43. Slow-oxidative muscle fibres have high resistance to fatigue.

a.True
b.False

44. A motor unit is a single muscle plus all the motor neurons that innervate it.

a.True
b.False

45. The T tubule ranges transversely to the surface of the muscle cell membrane.

a.True
b.False

46. Anaerobic exercise is endurance-type exercise.

a.True
b.False

47. All skeletal muscles are attached to the skeleton.

a.True
b.False

48. All smooth muscle is myogenic.

a.True
b.False

49. In order for relaxation to occur, ACh must be removed from the muscle cell’s receptors.

a.True
b.False

50. The larger the motor units within a muscle, the more precisely controlled the gradations of contraction.

a.True
b.False

51. The H zone of the sarcomere consists of myosin but does not contain actin.

a.True
b.False

52. Atrophy can develop in a muscle by either denervation or disuse.

a.True
b.False

53. Central fatigue of a muscle results directly from the accumulation of lactic acid in the muscle.

a.True
b.False

54. Skeletal muscle fibres are formed during embryonic development by the fusion of many smaller cells.

a.True
b.False

55. Slow-oxidative muscle fibres would be found in high density in the leg muscles of Olympic sprinters.

a.True
b.False

56. The functional unit of skeletal muscle is the myofibril.

a.True
b.False

57. The work performed by a muscle is the force it develops divided by distance.

a.True
b.False

58. A skeletal muscle produces motion by pulling the origin toward its insertion.

a.True
b.False

59. Muscle tension does not develop in isometric contractions.

a.True
b.False

60. The shorter a muscle fibre is before the onset of a contraction, the greater the force that can be developed upon the subsequent contraction because the thin filaments are already partially slid inward.

a.True
b.False

61. With twitch summation, the muscle fibre is stimulated so rapidly that it does not have an opportunity to return to resting potential between stimuli.

a.True
b.False

62. Muscle cells are the only cell types that contain intracellular contractile proteins.

a.True
b.False

63. Muscle relaxation does not take place until all the ATP is used up.

a.True
b.False

64. Denervated muscle fibres become progressively smaller and their content of actin and myosin decreases.

a.True
b.False

65. The heart initiates its own action potentials without any external influence.

a.True
b.False

Indicate the answer choice that best completes the statement or answers the question.

66. Which of the following areas is the origin of a muscle?

a.the main, thick part of the structure
b.the middle, thin part of the structure
c.the movable end of attachment
d.the stationary end of attachment

67. Which of the following would happen if ATP supplies became very low or were not available in a muscle cell?

a.An increase in tension would develop.
b.Cross bridges would detach from actin.
c.Muscles would relax.
d.ATP would not be required for detachment from actin.

68. How are sarcomeres arranged end to end?

a.as fascicles
b.as myofibrils
c.as bands
d.as perimysia

69. Which of the following composes thick filaments in skeletal muscle?

a.actin
b.troponin and tropomyosin
c.myosin
d.actin, troponin, and tropomyosin

70. Which of these statements correctly describes why you are able to repeatedly contract and relax your muscles of respiration, allowing you to breathe in and breathe out?

a.As soon as all the Ca2+ stored in the lateral sacs of the sarcoplasmic reticulum is used up, muscle relaxation occurs.
b.After the muscle cells become excited, acetylcholinesterase maintains the action of acetylcholine.
c.When there is no longer a local action potential in the muscle cell, Ca2+ is actively transported back into the lateral sacs of the sarcoplasmic reticulum.
d.ATP is not available soon after the contraction.

71. Which of the following are in the I band of the sarcomere?

a.overlapping thin and thick filaments
b.thick filaments only
c.thin filaments only
d.two Z lines

72. Muscles developing tension while lengthening are performing what type of contractions?

a.concentric
b.eccentric
c.isometric
d.fatiguing

73. Fatigue is the failure of a muscle fibre to maintain which of the following as a result of previous contractile activity?

a.excitability
b.muscle mass
c.tension
d.sarcomere number

74. Which of the following statements is NOT characteristic of cross bridges?

a.They are a component of thin filaments.
b.They are composed of myosin.
c.They have an actin binding site.
d.They have an ATPase binding site.

75. Which of the following correctly describes multiunit smooth muscle?

a.It is chemically activated.
b.It is under ANS control.
c.It is found in the walls of the digestive system.
d.It is the most dominant component of smooth muscle.

76. Which of these statements correctly describes the corticospinal system?

a.It consists of fibres that originate within the primary motor cortex and terminate on motor neurons.
b.It involves the motor regions of the cortex, the cerebellum, the basal nuclei, and the thalamus.
c.It is concerned primarily with regulation of overall body posture.
d.It consists of fibres that originate within the parietal lobe and terminate on the posterior grey horn of the spinal cord.

77. What can activate the stretch receptors in the central portion of the muscle spindle?

a.passive stretch of the skin overlying the muscle
b.contraction of the central portions of the muscle fibre
c.gamma motor neuron stimulation
d.an alpha motor neuron

78. Which of these statements does NOT correctly describe steroids?

a.Steroids can increase muscle mass when used in large amounts.
b.Anabolic steroids and their derivatives are controlled substances in Canada.
c.Addiction to anabolic steroids is possible.
d.In females, anabolic steroids may favour ovulation.

79. What causes the striated appearance of skeletal muscle?

a.regular arrangement of the T tubules running transversely through the muscle fibre
b.presence of the Z lines extending down the middle of the I bands
c.presence of gap junctions
d.regular arrangement of highly organized thick and thin filaments

80. Which of the following compounds binds with the calcium that enters the cell during smooth muscle excitation?

a.calmodulin
b.inactive myosin kinase
c.troponin
d.myosin

81. The striated appearance of skeletal muscle is due to regular orderly arrangement of which of the following?

a.T tubules
b.lateral sacs of the sarcoplasmic reticulum
c.motor units
d.thick and thin filaments into A and I bands

82. What is the first means by which ATP is produced at the onset of contractile activity?

a.transfer of energy and phosphate from creatine phosphate to ADP
b.oxidative phosphorylation
c.glycolysis
d.degradation of myoglobin

83. In the body’s lever systems, what are the fulcrums represented by?

a.joints
b.long bones
c.tendons
d.short bones

84. The regulation of smooth muscle contraction is mediated by the phosphorylation of which filaments in response to calcium binding to proteins?

a.myosin, calmodulin
b.actin, calmodulin
c.troponin, calmodulin
d.myosin, troponin

85. Muscle fibres are some of the longest cells in the body. How long can they be?

a.1 to 2 micrometres
b.2 to 4 micrometres
c.10 to 100 micrometres
d.500 to 1000 micrometres

86. Which of these muscle types is striated and contains gap junctions?

a.single-unit smooth muscle
b.multiunit smooth muscle
c.cardiac muscle
d.skeletal muscle

87. During aerobic exercise, what is the primary means by which ATP is produced for contractile activity?

a.accumulation of creatine phosphate
b.fermentation
c.oxidative phosphorylation
d.glycolysis

88. Which of the following is NOT a normal, age-related change that occurs in muscles of older individuals?

a.reduction in the number of fibres
b.reduction in the size of the fibres
c.large reduction in the blood supply
d.reduction in adaptation to exercise

89. Which of the following provides the energy for cross-bridge cycling during muscle contraction?

a.acetylcholine
b.Ca2+
c.ATP
d.myosin

90. Which of the following properties characterizes fast oxidative (type IIa) muscle fibres?

a.high myosin–ATPase activity
b.low myosin–ATPase activity
c.low oxidative capacity
d.high oxidative capacity

91. Which of these statements correctly describes functional syncytium of cardiac muscles cells?

a.They are striated.
b.They exhibit muscle tone.
c.They have a short refractory period.
d.They work as a unit mechanically and electrically.

92. Which of these statements correctly describes myosin?

a.It is found in the A band.
b.It is found in the I band.
c.It is the primary protein found in the thin filaments.
d.It contracts during muscle contraction because it is one of the contractile proteins.

93. Which of these statements does NOT correctly describe smooth muscle?

a.It can develop less tension per unit of cross-sectional area compared to skeletal muscle.
b.It can maintain tension with comparatively less ATP consumption than skeletal muscle.
c.It lacks troponin and tropomyosin.
d.The range of lengths over which it is able to develop near maximal tension is much greater than for skeletal muscle.

94. Which of these statements correctly describes intrafusal muscle fibres?

a.They are supplied by alpha motor neurons.
b.They are found within muscle cell membrane.
c.They contain contractile elements.
d.They contain sensory nerve endings that are activated by stretch.

95. Which of these statements correctly describes twitch summation?

a.The muscle fibre is restimulated before the action potential has returned to resting potential.
b.The muscle fibre is restimulated before the filaments have completely returned to their resting position.
c.Stronger muscle contractions occur with stronger action potentials.
d.Weaker muscle contractions occur despite stronger action potentials.

96. Which of these actions happens during contraction of skeletal muscle fibres?

a.Contractile proteins contract.
b.Thin filaments slide inward toward A bands’ centres as a result of cycles of cross-bridge binding and bending.
c.Thick and thin filaments become tightly coiled, thus shortening the sarcomere.
d.I bands slide between A bands.

97. Which of these statements correctly describes the H zone?

a.It is the area within the middle of the Z lines where the thin filaments do not reach.
b.It shortens or disappears during contraction.
c.It contains only thin filaments.
d.It is the area within the middle of the I band.

98. For which of these purposes are stretch reflexes important?

a.for maintaining balance and posture
b.for providing afferent information coordinating complex muscle activity
c.for determining the level of tone
d.for prevention of muscle injury

99. Which of these statements correctly describes gap junctions?

a.They allow action potentials to spread from cell to cell.
b.They are the junctions between the muscle fibres within a motor unit.
c.They are found only in smooth muscle.
d.They are the junctions between the autonomic nervous system and smooth muscle cells.

100. Which of these statements describes cross bridges?

a.They extend between the A and the I bands, and bend to pull the bands together during muscle contraction.
b.They are formed by the spherical actin molecules.
c.They extend from the thick filaments and bind to actin, then bend to pull the thin filaments in closer together during muscle contraction.
d.The A band is shorter than the I band.

101. Which of the following is a characteristic feature of isometric muscle contractions?

a.They occur at constant tension.
b.The muscle shortens.
c.They are used for body movements.
d.They occur at constant length.

102. What happens when a muscle atrophies?

a.The muscle fibres split lengthwise.
b.The muscle decreases in mass and becomes weaker.
c.The muscle fibres increase in diameter.
d.The muscle fibres undergo mitotic cell division.

103. Which of these statements does NOT correctly describe cross bridges?

a.They are formed by the globular heads of the myosin molecules as they protrude from the thick filaments.
b.They bind to actin during muscle contraction.
c.They are not found in the I band.
d.They bind with troponin and tropomyosin during muscle contraction to pull them away from the actin helical chain.

104. Which of the following actions is involved in developing tension in muscle fibres?

a.contraction of sarcomeres
b.lengthening of sarcomeres
c.pushing of myosin by actin
d.elongation of myosin fibres

105. If you wanted to pick up something heavier than your pencil, you would need to have a stronger muscle contraction. Which of these actions might accomplish this?

a.Stimulate more motor units.
b.Decrease the frequency of stimulation to allow a more prolonged contraction to occur.
c.Decrease the refractory period.
d.Block acetylcholinesterase at the neuromuscular junction to allow acetylcholine to function longer.

106. Which of these conditions occurs as the result of a lack of acetylcholinesterase in the synaptic cleft?

a.decreased acetylcholine production by the motor neuron
b.relaxation of the muscle fibre
c.excessive, continuous stimulation of the muscle fibre
d.inability of the motor neuron to stimulate the muscle fibre

107. Which of these characteristics does NOT apply to smooth muscle?

a.It is under involuntary control.
b.Light chains are crucial.
c.Its contraction is initiated neurogenically.
d.It is found in the walls of hollow tube-like organs.

108. Which of these statements describes the sliding-filament mechanism of muscle contraction?

a.A bands slide in closer between the I bands.
b.Thin filaments slide inward toward the centre of the A band.
c.Z lines slide between the T tubules.
d.Contractile proteins contract, thus shortening sarcomeres.

109. Which of the following characteristics are shared by all three types of muscle tissues?

a.contains myosin and actin
b.neurogenic
c.striated
d.considered to be under voluntary control

110. Which statement is characteristic of most of the body’s lever systems?

a.They work at mechanical advantage.
b.They work at a mechanical disadvantage.
c.Muscles must exert lesser forces than the load.
d.Muscles must exert greater forces than the load.

111. Which of these statements correctly describes muscle tension?

a.It is created during muscle contraction as the tension generated by the contractile elements is transmitted via the connective tissue and tendons to the bones.
b.It is the force exerted on a muscle by the weight of an object.
c.It is greater than the load tension during an isometric contraction.
d.It is less than the load tension during isometric contraction.

112. What is the cause of enlargement of muscle due to weight lifting?

a.hypotrophy
b.hyperplasia
c.increased production of actin and myosin
d.dystrophy

113. Which of these statements applies to eccentric muscle contractions?

a.The development of tension occurs at constant muscle length.
b.The muscle lengthens while contracting.
c.The muscle shortens while contracting.
d.Muscle length and tension will vary throughout a range of motion.

114. Which of the following happens during a cross-bridge cycle in skeletal muscle?

a.The cross bridge is energized as myosin and ATPase activity hydrolyzes ATP.
b.The myosin cross bridge is able to bind with a troponin molecule when Ca2+ pulls the troponin–tropomyosin complex aside.
c.The linkage between actin and the myosin cross bridge is broken at the end of the cross-bridge cycle as Mg2+ binds to the cross bridge.
d.The power strokes of all cross bridges are directed toward the periphery of the thick filament.

115. Which of the following events is NOT involved in the relaxation of muscle?

a.Acetylcholine is destroyed by acetylcholinesterase.
b.There is no longer a local action potential.
c.The T tubules actively take up the Ca2+ that was released.
d.The actin and myosin molecules are no longer bound together.

116. Which of these statements correctly describes actin?

a.It has ATPase activity.
b.It is shaped like a golf club.
c.It is a regulatory protein.
d.It forms a helical chain that forms the main structural component of the thin filaments.

117. What happens during coactivation?

a.All the muscle fibres in a skeletal muscle are activated simultaneously.
b.The gamma motor-neuron and alpha motor-neuron systems to a skeletal muscle are activated simultaneously.
c.All the cross bridges within a single skeletal muscle are activated simultaneously.
d.The primary (annulospiral) and secondary (flower-spray) endings within a muscle spindle are activated simultaneously.

118. Which of these muscles have motor units with the highest innervation ratio?

a.leg muscles
b.arm muscles
c.muscles of the trunk
d.muscles that move the fingers

119. Which of the following is the first step in excitation–contraction coupling?

a.Exposed actin sites bind with myosin cross bridges.
b.Troponin binds calcium.
c.Calcium is released from the sarcoplasmic reticulum.
d.Sodium channels open in the fibre’s membrane.

120. Which of these statements correctly describes fast glycolytic (type IIb) fibres?

a.They contain an abundance of mitochondria.
b.The muscle fibre diameter is small.
c.They are most abundant in muscles specialized for maintaining low-intensity contractions for long periods of time without fatigue.
d.They can be converted into fast oxidative fibres by regular endurance activities.

121. Which muscle type is myogenic?

a.skeletal muscle
b.single-unit smooth muscle
c.multiunit smooth muscle
d.both skeletal and cardiac muscle

122. Which of these statements applies to T tubules?

a.They store Ca2+.
b.They run longitudinally between the myofibrils.
c.They store ATP.
d.They provide a means of rapidly transmitting the action potential from the surface into the central portions of the muscle fibre.

123. Binding of which substance to myosin permits cross bridge of which action between actin and myosin?

a.Binding ATP will bind actin and myosin.
b.Binding ATP will detach actin and myosin.
c.Binding calcium will bind actin and myosin.
d.Binding calcium will detach actin and myosin.

124. Which of these statements correctly describes single-unit smooth muscle?

a.It contains no gap junctions and forms functional syncytia.
b.It is self-excitable.
c.It is found in the walls of the ventricles.
d.It is found in the iris of the eye.

125. Which of these statements correctly describes the length–tension relationship?

a.It refers to the relationship between the length of the muscle before the onset of contraction and the tetanic tension that each contracting fibre can subsequently develop at that length.
b.It is based on the amount of overlap of thick and thin filaments.
c.It allows no tension to develop if the whole muscle is stretched to 30 percent longer than its optimal length.
d.Within the body, it is limited to a functional range because of limitations on muscle length imposed by attachment to the skeleton.

126. What initiates contraction of smooth muscle?

a.stimulation by motor neurons
b.inhibition of acetylcholinesterase
c.membrane potential drifting to threshold
d.excitation of the gap junctions by transmitter substance

127. Which of these actions happens during muscle contraction?

a.The contractile proteins contract.
b.The A band becomes shorter.
c.The H zone becomes smaller or disappears.
d.The I band remains unchanged.

128. Which of these factors is NOT a determinant of whole muscle tension?

a.the number of muscle fibres contracting
b.the tension produced by each contracting fibre
c.the extent of motor-unit recruitment
d.the proportion of each motor unit contracting at any given time

129. Which of these statements does NOT apply to cardiac muscle?

a.It contains gap junctions.
b.It is found only in the heart.
c.It is self-excitable.
d.It lacks tropomyosin.

130. What causes muscular fatigue?

a.lactic acid accumulation
b.depletion of calcium
c.depletion of sodium
d.glycogenesis

131. Which of these characteristics would NOT be exhibited in the muscle cells of a marathon runner’s legs?

a.high resistance to fatigue
b.low myoglobin content
c.low glycogen content
d.slow speed of contraction

132. Which of these statements correctly describes twitch summation?

a.It is a means by which weak muscle contraction may be accomplished.
b.It results from increasing the number of motor units that are firing within a muscle.
c.A high level of calcium ion is not required in twitch summation.
d.It results from increasing the frequency at which motor units are firing within a muscle.

133. Which of these structures controls the conscious initiation of muscle contraction?

a.the spinal cord
b.the brain stem
c.the cerebral cortex
d.the thalamus

134. What is the term for the region between two Z lines?

a.muscle fibre
b.myofibril
c.myofilament
d.sarcomere

135. Which of these events results from disruption of a motor system that supplies inhibitory presynaptic inputs to motor neurons?

a.uncoordinated, clumsy movements
b.spastic paralysis
c.paraplegia
d.suppression of reflex activity

136. Which of these statements correctly describes foot proteins?

a.They span the gap between a lateral sac of the sarcoplasmic reticulum and the cell membrane.
b.They are believed to serve as Ca2+ channels.
c.They project from the thick filaments, bind to the thin filaments, and subsequently bend to pull the thin filaments inward toward the A band’s centre during muscle contraction.
d.Each contains two subunits arranged in a specific pattern.

137. Which of these statements correctly describes a functional syncytium?

a.It is a pair of agonist muscles that function together to move a joint.
b.It can be excited to contract as a unit.
c.It is a functional junction between a smooth muscle fibre and an autonomic nerve ending.
d.It refers to the muscle at the base of hair follicles.

138. Which of these statements correctly describes a motor unit?

a.a single motor neuron plus all the muscle fibres it innervates
b.a single muscle fibre plus all the motor neurons that innervate it
c.all the motor neurons supplying a single muscle
d.one pair of antagonistic muscles

139. Which of these statements correctly describes actin?

a.It is spherical.
b.It contains a globular head that forms the cross bridges between the thick and thin filaments.
c.It is referred to as a regulatory protein.
d.It is inhibited by Ca2+.

140. Which of these statements does NOT correctly describe different types of muscle fibres?

a.The higher the ATPase activity, the faster the speed of contraction.
b.Muscles that have high glycolytic capacity and large glycogen stores are more resistant to fatigue.
c.Muscles with high ATP-synthesizing ability are more resistant to fatigue.
d.Oxidative types of muscle fibres contain myoglobin.

141. Which of these statements correctly describes pacemaker activity?

a.It refers to spontaneous depolarizations of the membrane resulting from shifts in passive ionic fluxes accompanying automatic changes in channel permeability.
b.It refers to spontaneous depolarizations of the membrane due to cyclical changes in Na+–K+-pump activity.
c.It is characteristic of single-unit smooth muscle but is not found in any other muscle type.
d.It is characteristic of multiunit muscle but is not found in any other muscle type.

142. Which of the following events happens during excitation–contraction coupling?

a.The action potential travels down the thin myofilaments.
b.Ca2+ is released from the sarcoplasmic reticulum.
c.Ca2+ is taken up by the sarcoplasmic reticulum.
d.Calcium blocks the binding sites on the actin molecules.

143. Which of these types of muscle cells are NOT capable of spontaneous depolarization?

a.single-unit smooth muscle cells
b.multiunit smooth muscle and skeletal muscle cells
c.cardiac muscle and skeletal muscle cells
d.single-unit smooth muscle and multiunit smooth muscle cells

144. Which of these statements applies to T tubules?

a.They form the Z lines.
b.They store Ca2+.
c.They provide a means of rapidly transmitting the action potential to the central portions of the muscle fibre.
d.They allow for nutrients to be carried into the cell.

145. Which of these factors is characteristic of cardiac muscle tissue?

a.well-developed sarcoplasmic reticulum
b.fast myosin ATPase activity
c.neurogenically initiated contraction
d.presence of gap junctions

146. Which of these components are involved with regulation of cross-bridge attachment activity?

a.calcium ions and troponin
b.troponin and titin
c.tropomyosin and calmodulin
d.titin only

147. Which of these factors is involved in the gradation of muscle contraction?

a.greater number of muscle fibres
b.variation in the frequency of action potentials initiated in each muscle fibre
c.variation in the size of the action potentials initiated in each muscle fibre
d.variation in the distance action potentials can travel

148. Which of the following directly blocks cross bridge interaction between actin and myosin in skeletal muscle?

a.acetylcholine
b.Z lines
c.calcium
d.tropomyosin

149. How does an action potential spread rapidly to the central portions of a muscle cell?

a.by means of the Z lines
b.by means of the sarcoplasmic reticulum
c.by means of the H zone
d.by means of the T tubules

150. Which of these substances is required for contraction of smooth muscle fibres?

a.sodium ions
b.calmodulin
c.potassium ions
d.myosin

151. If the load on a muscle is increased, eventually a load will be reached at which the velocity of shortening becomes zero. What is the term for the muscle contraction at this point?

a.concentric
b.eccentric
c.isotonic
d.isometric

152. Which of these activities is involved in the process of muscle relaxation?

a.Acetylcholinesterase promotes the concentration of acetylcholine to allow the muscle membrane to return to resting potential.
b.Ca2+ is actively taken up by the lateral sacs of the sarcoplasmic reticulum when there is no longer a local action potential.
c.The cross bridges from the thick filaments bind to the thin filaments and bend in such a way as to return the filaments to their original resting position.
d.ATP becomes unavailable.

153. Which of these statements correctly describes myoglobin?

a.It can store small amounts of CO2.
b.It increases the rate of O2 transfer from blood into muscle fibres.
c.It is abundant in fast glycolytic fibres.
d.It is abundant in slow red fibres.

154. Which of these methods is NOT a method of gradation of skeletal muscle contraction?

a.twitch summation
b.motor unit recruitment
c.varying the number of motor units stimulated
d.stimulating variable portions of each motor unit

155. Which of these statements correctly describes the length–tension relationship of skeletal muscle?

a.When a muscle is maximally stretched, it can develop the most tension upon contraction because the thin filaments can slide a maximal distance.
b.Maximum tension can be developed if the muscle is at its shortest length at the onset of contraction.
c.In the body, the relaxed length of a muscle occurs at its optimal length.
d.When the initial length of a muscle prior to contraction becomes very short, tension is decreased during contraction.

156. Which of these statements does NOT correctly describe cross bridges?

a.They are the globular heads of myosin molecules.
b.They have actin binding sites that are normally covered by troponin and tropomyosin, except during excitation–contraction coupling.
c.They bind with actin and then bend to pull the thin filaments inward during contraction according to the sliding filament mechanism.
d.They require Mg2+ to bind ATP to them.

157. Which of these statements correctly describes smooth muscle?

a.It composes the walls of the heart.
b.Its cells are multinucleated.
c.Its cells are spindle shaped.
d.Its cells lack actin and myosin.

158. Which one of the following is the function of tropomyosin?

a.to bind Ca2+
b.to form attachments with myosin cross bridges
c.to serve as an ATPase
d.to prevent myosin cross bridges from attaching to thin filaments

159. Which of these statements does NOT correctly describe cross bridges?

a.They bind to actin during muscle contraction.
b.They are formed by the globular heads of the myosin molecules.
c.They consist of troponin and tropomyosin protruding from the actin helix.
d.They bend during muscle contraction.

160. Which of these events happens when an action potential reaches the presynaptic terminal of the motor neuron?

a.Calcium is released inside the muscle fibre.
b.Acetylcholine is released into the synaptic cleft.
c.Acetylcholinesterase is released into the synaptic cleft.
d.Physical contact between the motor neuron and the muscle fibre occurs.

161. Submaximal isometric contractions are important for which of the following activities?

a.moving large objects
b.walking
c.maintaining posture
d.writing

162. Which of the following applies during an isotonic contraction of a muscle in the arm?

a.The muscle does NOT contract.
b.The muscle does NOT change length.
c.The tension in the muscle does NOT overcome a load.
d.The tension in the muscle remains constant.

163. Which of these statements correctly describes Z lines?

a.They are formed by the T tubules.
b.They extend down the middle of the I band.
c.They are formed by the cross bridges.
d.They are the filaments.

164. Why must the oxygen debt be “paid off” following rigorous muscular activity?

a.Creatine phosphate must be regenerated.
b.Lactic acid must be repleted.
c.Glycogen stores must be depleted.
d.Creatine phosphate must be depleted.

165. When does spastic paralysis occur?

a.when descending excitatory pathways are destroyed
b.when excitatory inputs to motor neurons are unopposed because of disruption of an inhibitory system in the brain stem
c.when muscle spindles are destroyed
d.when the cerebellum is damaged

166. Which of these statements correctly describes summation?

a.It results from increases in cytosolic calcium levels.
b.It refers to the pumping of calcium into the sarcoplasmic reticulum.
c.It can be enhanced by allowing a cell to completely relax.
d.It rarely results in tetany.

167. Which of these statements correctly describes myosin?

a.It is spherical in shape.
b.It is the main structural component of the thin filaments.
c.It is referred to as a contractile protein.
d.It consists of four identical protein subunits.

168. Which of these factors causes muscle relaxation?

a.addition of magnesium to muscle cells
b.ACh hyperactivity
c.return of calcium to lateral sacs
d.lack of ATP

169. Which of the following statements applies when trying to pick up a book?

a.Muscle tension must be less than load.
b.The muscle must lengthen during contraction.
c.Muscle tension remains constant as the muscle changes length.
d.Muscle length remains constant as the muscle tension changes.

170. What is the functional unit of skeletal muscle?

a.largest contractile component of a muscle fibre
b.area between two Z lines
c.sarcoplasmic reticulum
d.area between two I bands

171. Which of these structures is the smallest unit of contraction within a skeletal muscle?

a.a myofibril
b.a muscle fibre
c.a thin filament
d.a sarcomere

172. During contraction, asynchronous cycling of cross bridges _______________.

a.prevents tetany
b.prevents thick filaments from slipping backward
c.prevents thin filaments from slipping backward
d.utilizes less ATP than prior to contraction

173. The sarcoplasmic reticulum stores which substance when a muscle is relaxed, and releases it for binding to which substance during contraction?

a.calcium; troponin
b.calcium; tropomyosin
c.sodium; tropomyosin
d.potassium; tropomyosin

174. Which of these statements correctly describes the summation of simple twitches?

a.They can occur from the long duration of the action potential in a muscle fibre.
b.They reduce the tension in a muscle.
c.They result from the slow stimulation of a muscle fibre.
d.The twitches from action potentials add together.

175. Which of these statements correctly describes contraction in skeletal and smooth muscle?

a.In skeletal muscle, calcium ion mediates changes in thin filaments that lead to cross-bridge activity; in smooth muscle, calcium ion mediates changes in thick filaments that lead to cross-bridge activity.
b.In skeletal muscle, troponin and tropomyosin are regulatory proteins; in smooth muscle, troponin is the only regulatory protein on thick filaments.
c.In skeletal muscle, calcium ion binds to troponin; in smooth muscle, calcium ion binds to calmodulin.
d.In skeletal muscle, calcium ion binds to calmodulin; in smooth muscle, calcium ion binds to troponin.

176. Which of these statements correctly describes troponin?

a.It binds with calcium during contraction of skeletal muscle.
b.It breaks down actin.
c.It breaks down myosin.
d.It forms the boundaries of a sarcomere.

177. Which of the following structures does NOT directly influence motor neurons?

a.primary motor cortex
b.cerebellum
c.brain stem
d.afferent neurons (through intervening interneurons)

Enter the appropriate word(s) to complete the statement.

178. Slow-oxidative fibres are type ____________________ fibres in the muscle.

179. Skeletal muscles are stimulated to contract by release of the neurotransmitter ____________________.

180. The contractile response of a muscle fibre to a single action potential is called a(n) ____________________.

181. Twitch summation is similar to the ____________________ summation of EPSPs.

182. The functional unit of skeletal muscle is a(n) ____________________.

183. A(n) ____________________ develops following sustained anaerobic activity of muscles.

184. A(n) ____________________ is a motor neuron and all the muscle fibres it recruits.

185. In smooth muscle, Ca2+ binds with the protein ____________________, which is structurally similar to troponin.

186. ____________________ occurs when acetylcholine is no longer available in adequate amounts to stimulate muscle fibres.

187. In a state of ____________________, a muscle cannot maintain any kind of tension.

188. The ____________________ is the extensor muscle found in the thigh that contracts during the patellar tendon reflex.

189. The ____________________ component is the noncontractile tissue part of a muscle.

190. If a muscle cell is excited, ____________________ is released from the sarcoplasmic reticulum.

191. ____________________ is the pigment that can store small amounts of oxygen in the skeletal muscle.

192. The _____________________ is the descending pathway that is concerned primarily with regulation of posture involving involuntary movements of the trunk and limbs.

193. The immediate source of additional ATP in muscle fibres is ____________________.

194. ____________________ refers to the series of events linking muscle excitation to muscle contraction.

195. During the ____________________ stroke, cross bridges of myosin pull the actin filaments in the sarcomere.

196. For a(n) ____________________ isotonic contraction, the contraction resists the stretching of the muscle.

197. The ____________________ is the descending motor pathway that mediates performance of fine, discrete voluntary movements of the hands.

198. The source of calcium in smooth muscle is the ____________________.

199. The immediate source for supplying additional ATP at the onset of exercise is ____________________.

200. The only energy source that can be used directly by the contractile machinery of a muscle fibre is ____________________.

201. ____________________ proteins are calcium-release channels in the muscle cell.

202. ____________________ and ____________________ are referred to as contractile proteins, whereas ____________________ and ____________________ are referred to as regulatory proteins.

203. ____________________ refers to paralysis of the legs resulting from lower spinal cord injury.

204. For every muscle, there is an optimal length at which maximum ____________________ is achieved.

205. ____________________ provides the most ATP molecules for use by muscle fibres contracting over a long period of time.

206. The ____________________ is a modified endoplasmic reticulum within muscle.

207. The gradation of whole-muscle tension depends on the number of ____________________ that contract.

208. ____________________ are the intracellular signal for contraction.

209. Thick filaments are made up of the protein ____________________, whereas thin filaments are composed of the three proteins ____________________, ____________________, and ____________________.

210. The three types of muscle tissue are ____________________, ____________________, and ____________________.

Match the bands, labelled a. through c., with the descriptions. (Options may be used more than once or not at all.)

a.A band
b.I band
c.H zone

211. composed of thin filaments only

212. composed of thick filaments only

213. composed of thick and thin filaments

214. shortens during muscle contraction

215. remains the same size during muscle contraction

Match the muscle fibre types, labelled a. through c., with the characteristics. (Options may be used more than once or not at all.)

a.slow-oxidative fibre
b.fast-oxidative fibre
c.fast-glycolytic fibre

216. has myosin ATPase activity

217. most resistant to fatigue

218. most readily fatigues

219. has numerous mitochondria

220. can be transformed into another fibre type by specific training

221. contains considerable myoglobin

222. found predominantly in muscles designed for endurance

223. has the largest diameter

224. has abundant glycolytic enzymes

225. the most powerful fibre

226. found predominantly in muscles adapted for short-duration, high-intensity activities

227. produces the most lactic acid

228. hypertrophies in response to weight training

229. uses up considerable glycogen

230. requires a constant supply of oxygen

Match the types of muscles, labelled a. and b., with the characteristics.

a.isometric contraction
b.isotonic contraction

231. muscle tension exceeds the load

232. load exceeds muscle tension

233. length changes

234. length remains constant

235. tension remains constant

236. important in maintaining posture

237. used to accomplish movement

238. does not accomplish any work

Match the muscle-tension receptors, labelled a. through c., with the characteristics. (Options may be used more than once or not at all.)

a.muscle spindle
b.Golgi tendon organ
c.both of these receptors

239. monitors change in muscle length

240. detects change in muscle tension

241. activated by muscle stretch

242. initiates a monosynaptic reflex

243. unless compensatory measures are taken, this receptor becomes slack

244. involved in negative feedback

245. provides information to motor regions of the brain

Match the skeletal muscle proteins, labelled a. through f., with the descriptions. (Options may be used more than once or not at all.)

a.actin only
b.myosin only
c.actin and myosin
d.troponin–tropomyosin complex
e.actin, troponin, and tropomyosin
f.actin, myosin, troponin, and tropomyosin

246. found in the A band

247. found in the I band

248. contractile protein(s)

249. found in the H zone

250. regulatory protein(s)

251. found in thin filament

252. spherical

253. possess cross bridges

254. shape consists of two globular heads attached to a tail

255. found in thick filament

256. has (have) ATPase capacity

257. can bind with myosin during muscle contraction

258. lie(s) near the groove of the thin filament helix

259. found in the sarcomere

260. can bind with Ca2+ during contraction

261. form(s) a helical chain

Match the sarcomere components, labelled a. through d., with the characteristics. (Options may be used more than once or not at all.)

a.Z line
b.A band
c.I band
d.H zone

262. dark band

263. light band

264. contains only thick filaments

265. contains only thin filaments

266. contains partially overlapping thick and thin filaments

267. joins adjacent sarcomeres together

268. runs down the middle of the A band

269. runs down the middle of the I band

Match the types of muscles, labelled a. through g., with the properties in question. (Options may be used more than once or not at all.)

a.skeletal muscle only
b.single-unit smooth muscle only
c.cardiac muscle only
d.skeletal muscle and cardiac muscle
e.skeletal muscle and single-unit smooth muscle
f.single-unit smooth muscle and cardiac muscle
g.skeletal, single-unit smooth, and cardiac muscles

270. contain(s) actin, myosin, troponin, and tropomyosin

271. contain(s) gap junctions

272. innervated by motor neurons

273. self-excitable

274. maintain(s) a constant resting membrane potential unless stimulated

275. innervated by the autonomic nervous system

276. attached to bones

277. considered to be involuntary

278. Thick and thin filaments are highly organized into a banding pattern.

279. found in the heart

280. can exist over a variety of lengths with little change in tension

281. striated

282. found in the walls of hollow organs such as the stomach

283. behave(s) as a functional syncytium

284. under voluntary control

285. has/have a clear-cut, length-tension relationship

286. basis of contraction is cross-bridge interaction between actin and myosin

287. contraction triggered as Ca2+ physically pulls troponin and tropomyosin from its blocking position over actin’s binding sites for the cross bridges

288. Myosin must be phosphorylated before it can bind with actin

289. contain(s) T tubules

290. display(s) pacemaker potentials and slow-wave potentials

291. Match the muscle type with the correct characteristics by using the answer codes a. through e.

____ cardiac muscle
____ multiunit smooth muscle
____ single-unit smooth muscle
____ skeletal muscle

a. voluntary, neurogenic, and striated
b. voluntary, neurogenic, and nonstriated
c. involuntary, myogenic, and striated
d. involuntary, neurogenic, and nonstriated
e. involuntary, myogenic, and nonstriated

292. Which events involved in muscle cell contraction are sequenced in the correct order?

1. Sodium channels open, allowing sodium to flow in.
2. Impulse reaches axon’s synaptic knob.
3. ACh binds to receptors on sarcolemma.
4. Synaptic vesicles fuse with neuron’s membrane and release ACh via exocytosis.
5. If enough sodium moves into the muscle cell, an impulse (action potential) develops.

a.1, 2, 3, 4, 5
b.2, 1, 3, 4, 5
c.2, 4, 3, 1, 5
d.3, 4, 5, 1, 2

293. Match the muscle term with the correct characteristic by using the answer codes a. through e.

____ creatine phosphate
____ myoglobin
____ glycogen
____ lactic acid
____ glucose

a. a storage form of glucose used in muscle cells requiring rapid energy release
b. a molecule that can quickly, but temporarily, make ATP
c. an oxygen-storing protein that makes muscle tissue appear red
d. a fuel molecule for cell respiration or fermentation
e. fermentation product when our cells become anaerobic

294. Rank the following muscle cell components from largest to smallest.

1 troponin
2 myofibril
3 sarcomere
4 thin filament
5 muscle fibre

a.3, 4, 1, 5, 2
b.1, 2, 3, 5, 4
c.5, 4 ,3 , 1, 2
d.5, 2, 3, 4, 1

295. Describe how summations occur in muscle cells.

296. How does contraction of smooth muscle differ from that of skeletal muscle?

297. Compare and contrast isotonic versus isometric contractions.

298. What are the means by which skeletal muscle fibres utilize energy for contraction?

299. Describe calcium’s role in the contraction of the sarcomere in skeletal and cardiac muscle tissues.

Answer Key

1. False

2. False

3. False

4. True

5. True

6. True

7. False

8. True

9. True

10. False

11. False

12. True

13. True

14. False

15. True

16. True

17. False

18. False

19. True

20. True

21. False

22. True

23. False

24. True

25. True

26. False

27. False

28. True

29. True

30. True

31. False

32. True

33. False

34. True

35. True

36. True

37. False

38. True

39. False

40. False

41. False

42. True

43. True

44. False

45. True

46. False

47. False

48. False

49. True

50. False

51. True

52. True

53. False

54. True

55. False

56. False

57. False

58. False

59. False

60. False

61. False

62. False

63. False

64. True

65. True

66. d

67. a

68. b

69. c

70. c

71. c

72. b

73. c

74. a

75. b

76. a

77. c

78. d

79. d

80. a

81. d

82. a

83. a

84. a

85. c

86. c

87. c

88. c

89. c

90. a

91. d

92. a

93. a

94. d

95. b

96. b

97. b

98. a

99. a

100. c

101. d

102. b

103. d

104. a

105. a

106. c

107. c

108. b

109. a

110. a

111. a

112. c

113. b

114. a

115. c

116. d

117. b

118. d

119. d

120. d

121. b

122. d

123. b

124. b

125. c

126. c

127. c

128. d

129. d

130. a

131. b

132. d

133. c

134. d

135. b

136. b

137. b

138. a

139. a

140. b

141. a

142. b

143. b

144. c

145. d

146. a

147. b

148. d

149. d

150. b

151. d

152. b

153. b

154. d

155. a

156. b

157. c

158. d

159. c

160. b

161. c
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