front 1 Heat released from contracting muscles functions to __________. | back 1 maintain body temperature |
front 2 Voluntary control over swallowing, defecation, and urination is provided by muscles that __________. | back 2 guard entrances and exits |
front 3 The perimysium surrounds a bundle of muscle fibers called a __________. | back 3 fascicle |
front 4 Which connective tissue layer wraps the entire muscle? | back 4 epimysium |
front 5 Which structure in a muscle fiber or muscle cell is continuous with the sarcolemma and carries the signal to contract deep into the muscle cells? | back 5 T tubules |
front 6 Repeating functional units seen on the myofibrils are __________. | back 6 sarcomeres |
front 7 Which of the following is NOT found in a thin filament?
| back 7 myosin |
front 8 Which of the following is the dark band seen on myofibrils? | back 8 A band |
front 9 The neurotransmitter required to trigger skeletal muscle contraction is __________. | back 9 ACh |
front 10 What must bind to troponin in order to expose the active sites on actin? | back 10 Ca++ |
front 11 In a twitch, what is the phase in which tension rises to a peak? | back 11 Contraction phase |
front 12 All the muscle fibers and the single motor neuron that innervates them are called a __________. | back 12 motor unit |
front 13 What is the type of contraction in which the muscle does NOT change length and the contraction does NOT produce tension that exceeds the load? | back 13 isometric |
front 14 Which of the following produces ATP from glucose anaerobically? | back 14 glycolysis |
front 15 When glycolysis produces pyruvic acid faster than it can be used by the mitochondria, pyruvic acid is converted to ________________, which lowers the pH of body fluids. | back 15 lactic acid |
front 16 Which muscle fiber type contains abundant myoglobin and is specialized to contract for extended periods of time? | back 16 slow fiber |
front 17 What is the name of the structure that contains gap junctions and desmosomes and joins the plasma membranes of two cardiac muscle cells together? | back 17 intercalated discs |
front 18 What is the term for the ability of cardiac muscle cells to contract without neural stimulation? | back 18 automaticity |
front 19 Which of the following is NOT a characteristic of smooth muscle tissue?
| back 19 striations |
front 20 What is the term for the ability to function over a wide range of lengths? | back 20 plasticity |
front 21 A slightly higher maximum tension produced by sequential stimulation. | back 21 Treppe |
front 22 A single stimulus contraction-relaxation sequence in a muscle fiber. | back 22 Twitch |
front 23 The addition of one wave to another, increasing overall tension. | back 23 Wave summation |
front 24 Increased stimulation rate to the point where no relaxation phase is present. | back 24 Complete tetanus |
front 25 Increasing rate of stimulation, with brief periods of incomplete relaxation. | back 25 Incomplete tetanus |
front 26 Tension generated by myofibrils in contacted muscle. | back 26 Internal tension |
front 27 Muscles surround the orifices that serve as openings to the digestive and urinary system and allow for voluntary control of actions such as swallowing, defecation, and urination. | back 27 Guarding entrances and exits |
front 28 When body temperature falls below homeostatic levels, muscles contract and produce heat, which warms the body. | back 28 Maintenance of body temperature |
front 29 Tension produced in skeletal muscles during contractions allows for sustained positions, such as holding the head up, standing, and sitting upright. | back 29 Maintenance of body posture and position |
front 30 Contraction of muscles pull on tendons attached to bones, which creates motion in body parts such as raising an arm, swimming, and the coordinated movements of breathing. | back 30 Production of movement |
front 31 Muscles in the abdominal wall and floor of the pelvic cavity support the weight of visceral organs in the abdominal and pelvic regions. | back 31 Support of soft tissues |
front 32 Put in correct order:
| back 32 Arrival
|
front 33 Skeletal muscle is responsible for all of the following EXCEPT __________.
| back 33 production of vitamin D |
front 34 Skeletal muscle functions in __________.
| back 34 maintaining body temperature |
front 35 What is the functional unit of the muscle fiber? | back 35 sarcomere |
front 36 What is the membranous network that surrounds each myofibril? | back 36 sarcoplasmic reticulum |
front 37 The command to contract is conducted throughout the muscle fiber by the __________. | back 37 transverse tubules |
front 38 The part of the sarcomere that contains thick filaments but no thin filaments is the __________. | back 38 H zone |
front 39 Z lines __________.
| back 39 mark the boundaries between adjacent sarcomeres |
front 40 For tropomyosin to be shifted off its position covering the active sites of G actin molecules, calcium ions must bind to which structure? | back 40 troponin |
front 41 Which of the following descriptions of sarcomere components is FALSE?
| back 41 The I band contains the zone of overlap at its center. |
front 42 When Jennifer looks through the microscope at skeletal and cardiac muscles, she sees striations. What are these striations? | back 42 A bands and I bands |
front 43 The junction between a muscle cell and the neuron innervating that cell is the __________. | back 43 neuromuscular junction |
front 44 ACh is released from what structure? | back 44 synaptic terminal |
front 45 Which of the following does NOT happen when the action potential reaches the synaptic terminal?
| back 45 Potassium ions flood the intercellular space. |
front 46 The binding of ACh to the motor end plate causes a change in membrane permeability to __________. | back 46 Sodium |
front 47 Which of the following events in a muscle contraction marks the beginning of the relaxation of the muscle cell?
| back 47 detachment of cross-bridges |
front 48 What happens when the myosin head splits ATP into ADP and a phosphate group? | back 48 myosin reactivation |
front 49 Which of the following represents the correct sequence of events in a contraction cycle?
| back 49 active-site exposure, cross-bridge attachment, pivoting, cross-bridge detachment, myosin reactivation |
front 50 Action potentials must travel along which structure internal to the sarcolemma to cause the release of calcium ions from the sarcoplasmic reticulum? | back 50 T tubule |
front 51 Which of the following statements about muscle contraction is FALSE?
| back 51 When Ca2+ binds to a myosin head, it triggers the formation of a cross-bridge between myosin and actin. |
front 52 In __________ contraction, the peak tension developed is less than the resistance, and the muscle elongates as a result of the contraction of another muscle or the pull of gravity. | back 52 an eccentric |
front 53 Pushing against a locked door is an example of __________. | back 53 an isometric contraction |
front 54 In which part of the sarcomere are myosin heads able to form cross-bridges with actin? | back 54 zone of overlap |
front 55 When pyruvic acid is produced by anaerobic metabolism faster than it can be utilized, the surplus is converted to __________. | back 55 lactic acid |
front 56 When energy reserves in a muscle are exhausted and lactic acid levels increase, __________ occurs. | back 56 fatigue |
front 57 At peak levels of muscle exertion, mitochondrial activity can provide about only one-third of the ATP needed. The remainder is provided through __________. | back 57 glycolysis |
front 58 Which of the following statements about muscle fatigue and the recovery period is FALSE?
| back 58 Elevated oxygen demand in muscle tissue stops as soon as exercise activities cease. |
front 59 During moderate and peak exertion of skeletal muscles, the body experiences a higher temperature because of which of the following? | back 59 the reduction of energy captured by skeletal muscles as ATP during moderate and peak exertion |
front 60 Which type of muscle fiber allows for extremely quick contractions but fatigues quickly? | back 60 fast fibers |
front 61 Which type of muscle fiber is supplied by extensive blood vessels? | back 61 slow fibers |
front 62 What human muscles contain ONLY fast fibers? | back 62 hand muscles |
front 63 The length of time muscular contraction can be supported by glycolysis is called __________. | back 63 anaerobic endurance |
front 64 Which of the following features is found in cardiac muscle cells but NOT in skeletal and smooth muscle cells?
| back 64 intercalated discs |
front 65 Unique features of smooth muscles include which of the following? | back 65 plasticity |
front 66 True/False. Thick filaments are composed of myosin, troponin, and tropomyosin. | back 66 False. The thick filaments are composed of bundles of hundreds of myosin molecules. |
front 67 True/False. Aerobic endurance is determined by the amount of glucose and oxygen available to fuel mitochondrial activity, while anaerobic endurance is determined by the amounts of ATP and CP already available. | back 67 True. |
front 68 True/False. The duration of muscle contraction and the following relaxation are affected by levels of calcium ions in the sarcoplasm. | back 68 True. |
front 69 True/False. In isometric contraction, the muscle does not change in length. | back 69 True. |
front 70 True/False. The arrangement of myosin and actin fibers in skeletal, cardiac, and smooth muscles is identical. | back 70 False. Myosin and actin fibers are arranged similarly in skeletal and cardiac muscle; however, in smooth muscle the arrangement of myosin is scattered and actin fibers are loosely linked and incorporate the use of dense bodies. |
front 71 The layer of connective tissue that surrounds an individual muscle fiber is called the ______. | back 71 endomysium |
front 72 An individual contractile unit within a myofibril in a muscle fiber is called a(n) ____. | back 72 sarcomere |
front 73 During a sarcomere contraction, the A band length does not change, while the _____ move closer together. | back 73 Z lines |
front 74 What is the name of the enzyme in the synaptic cleft that breaks down the neurotransmitter that starts a muscle contraction? | back 74 AChE |
front 75 When a muscle fiber has produced more ATP than it currently needs, the energy is transferred to form another high-energy compound called ____. | back 75 creatine phosphate |
front 76 Muscle performance is considered in terms of power, the maximum amount of tension that can be produced by a muscle or muscle group, and_____ , the amount of time an individual can perform an activity. | back 76 endurance |
front 77 While you sit at the computer reading this question, the postural muscles in your back are involved in contractions that produce tension but do not shorten muscle length. These are called _____ contractions. | back 77 isometric |
front 78 Regular, repetitive, exhaustive stimulation of muscles leads to an increase in the number of mitochondria in those muscles. As a result, the muscles can be said to experience muscle _____ . | back 78 hypertrophy |
front 79 A blending of epimysium, perimysium, and endomysium that forms a broad sheet at the end of a muscle is known as ________. | back 79 an aponeurosis |
front 80 What are the three types of muscle tissue? | back 80 cardiac, smooth, skeletal |
front 81 Why are skeletal muscles often called voluntary muscles? | back 81 They contract when stimulated by motor neurons of the central nervous system. |
front 82 Repeating contractile units that make up a myofibril are called ________. | back 82 sarcomeres |
front 83 Nerves and blood vessels are contained within the connective tissues of the ________. | back 83 epimysium, perimysium, and endomysium |
front 84 The thinfilaments consist of ________. | back 84 a pair of F actin molecules twisted together |
front 85 The thick filaments consist of ________. | back 85 about 300 myosin molecules twisted around one another |
front 86 All of the muscle fibers controlled by a single motor neuron constitute a ________. | back 86 motor unit |
front 87 Why is control over leg muscles LESS precise than control over the muscles of the eye? | back 87 Many muscle fibers are controlled by a single motor neuron. |
front 88 According to the sliding filament theory, what is the physical change that takes place during contraction? | back 88 The thin filaments are sliding toward the center of the sarcomere alongside the thick filaments. |
front 89 Troponin and tropomyosin are two proteins that can prevent the contractile process by ________. | back 89 covering the active site and blocking the actin–myosin interaction |
front 90 The amount of tension produced by an individual muscle fiber ultimately depends on the ________. | back 90 number of pivoting cross-bridges |
front 91 The transmission of an action potential along the T tubules stimulates the release of calcium from which structure in the sarcomere? | back 91 terminal cisterna |
front 92 What determines the amount of tension produced in the skeletal muscle as a whole?
| back 92 all of the above |
front 93 Peak tension production occurs when all motor units in the muscle contract in a state of ________. | back 93 complete tetanus |
front 94 In an isotonic contraction, ________. | back 94 cross-bridges must produce enough tension to exceed the load to be moved |
front 95 Which of the following is an example of an isometric contraction? | back 95 holding a heavy stack of books above the ground |
front 96 A high blood concentration of the enzyme creatine phosphokinase (CPK) usually indicates ________. | back 96 serious muscle damage |
front 97 Mitochondrial activities are relatively efficient, but their rate of ATP generation is limited by the ________. | back 97 availability of oxygen |
front 98 Which of the following has been correlated with muscle fatigue? | back 98 a decline in pH within the muscle, which alters enzyme activities |
front 99 During the recovery period, the body's oxygen demand is ________. | back 99 elevated above normal resting levels |
front 100 Which type of muscle fiber is dominant in a muscle such as the gastrocnemius, a calf muscle that contracts during standing and walking? | back 100 slow fibers |
front 101 Extensive blood vessels, mitochondria, and myoglobin are found in the greatest concentration in ________. | back 101 slow fibers |
front 102 The length of time a muscle can continue to contract while supported by mitochondrial activities is referred to as ________. | back 102 aerobic endurance |
front 103 Which of the following may cause muscle atrophy?
| back 103 all of the above |
front 104 What type(s) of muscle tissue do(es) NOT contain sarcomeres?
| back 104 smooth |
front 105 Structurally, how do smooth muscle cells differ from skeletal muscle cells? | back 105 Smooth muscle cells lack myofibrils and sarcomeres. |
front 106 Which of the following is necessary for smooth muscle contraction? | back 106 Calcium ions must interact with calmodulin to trigger muscle contraction. |
front 107 Smooth muscle contractions in the respiratory passageways cause ________. | back 107 increased resistance to air flow |
front 108 Layers of smooth muscle in the reproductive tract of the female are important in ________.
| back 108 all of the above |
front 109 The cardiovascular system uses which types of muscle? | back 109 cardiac and smooth |
front 110 The area of the A band in the sarcomere consists of ________. | back 110 M line, H band, and zone of overlap |
front 111 The order of the sequential–cyclic reactions that occur at an active site during cross-bridging is ________. | back 111 attach, pivot, detach, return |
front 112 Excitation–contraction coupling forms the link between ________. | back 112 electrical activity in the sarcolemma and the initiation of a contraction |
front 113 Cardiac muscle has the feature of automaticity, which is the ability to contract without neural stimulation. Which of the following statements accurately explains this unique feature?
| back 113 Specialized pacemaker cells within the heart determine the rate of contraction of heart muscle. |
front 114 The phases of a single twitch, in sequential order, are ________. | back 114 latent period, contraction phase, relaxation phase |
front 115 After contraction, a muscle fiber returns to its original length through ________. | back 115 elastic forces and the movement of opposing muscles |
front 116 A muscle producing peak tension during rapid cycles of contraction and relaxation is said to be in ________. | back 116 incomplete tetanus |
front 117 The process of complete tetanus is reached by ________. | back 117 increasing the rate of stimulation until the relaxation phase is completely eliminated |
front 118 The bacterium Clostridium tetani causes prolonged muscle contractions by doing which of the following? | back 118 inhibiting the mechanism that suppresses motor neuron activity |
front 119 Which of the following would NOT be an effective source of energy for muscle contraction?
| back 119 DNA |
front 120 What are the two mechanisms used to generate ATP from glucose?
| back 120 aerobic respiration and anaerobic glycolysis |
front 121 In anaerobic glycolysis, glucose is broken down to pyruvic acid, which is converted to ________.
| back 121 lactic acid |
front 122 Johnny, a 55-pound 6-year-old boy, wants to be as strong as some of the professional weight lifters he sees on television. He goes outside, grabs the front bumper of his mother's SUV, and attempts to raise it off the ground. The SUV does not move, but Johnny has succeeded in demonstrating which kind of muscle contraction? | back 122 isometric |
front 123 On average, girls have smaller muscles and therefore less muscle mass than boys. Which hormones cause this difference between girls and boys? | back 123 growth hormone and testosterone |
front 124 Which hormone is responsible for stimulating muscle metabolism and increasing the force of contraction during a sudden crisis? | back 124 epinephrine |
front 125 Which type of skeletal muscle fibers has low fatigue resistance? | back 125 fast fiber |
front 126 Which of the following is an example of an activity that requires anaerobic endurance? | back 126 a 50-yard dash |
front 127 Athletes training to develop anaerobic endurance perform ________. | back 127 frequent, brief, intensive workouts |
front 128 What is the major support that the muscular system gets from the cardiovascular system? | back 128 nutrient and oxygen delivery and carbon dioxide removal |