Physio. quiz/exam 3
36 When a muscle contracts, exactly what structure gets shorter? A. the fascicles of a muscle B. the myosin molecules of a myofilament C. the actin molecules of a myofilament D. the sarcomeres of a myofibril
Answer is D: The length of the sarcomeres decreases.
7. Which of the events below is the FIRST to occur prior to a muscle cell contracting? A. ATP binds to myosin. B. ADP detaches from myosin. C. the active site on actin is exposed. D. Ca ++ is released from the sarcoplasmic reticulum.
Answer is D: The release of Ca from where it is stored (in the SR) is necessarybefore the active binding site of actin can be exposed.
42.Which of the following statements is most accurate? A. Myofilaments slide during isometric contractions. B. Muscle tension remains relatively constant during isotonic contraction. C. The I band lengthens during isotonic contraction. D. T tubules may be sliding during isotonic contraction.
B. *Muscle tension remains relatively constant during isotonic contraction.
81. The maximum power that can be developed by a skeletal muscle A. Is dependent of the initial length of the muscle incorrect B. Occurs with an isometric contraction incorrect C. Occurs when the muscle is moving a load at about one third of its maximum rate of shortening correct D. Depends on the load being moved by the muscle correct
B. *Occurs with an isometric contraction incorrect
93. Which of the following muscles typically operate under voluntary control? A.cardiac B.skeletal C.smooth
B. skeletal
45.After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction? A. the action potential stops going down the overloaded T tubules B. acetylcholinesterase destroying the ACh C. calcium ions returning to the terminal cisternae D. the tropomyosin blocking the myosin once full contraction is achieved
B.acetylcholinesterase destroying the ACh
54. Rigor mortis occurs because ________. A. proteins are beginning to break down, thus preventing a flow of calcium ions B. sodium ions leak into the muscle causing continued contractions C. no ATP is available to release attached actin and myosin molecules D. the cells are dead
C*no ATP is available to release attached actin and myosin molecules
89. striations, cylindrical cells, and multiple nuclei are observed in ________. A. Smooth muscle only. B. Skeletal and cardiac muscles. C. Skeletal muscle only. D. Cardiac muscle only
C. Skeletal muscle only.
69.. Which of the following correctly identifies muscle components in order from largest to smallest? A. Muscle fiber, fasciculus, myofibril B. Sarcolemma, sarcoplasm, fasciculus C. Fasciculus, muscle fiber, myofibril D. Fasciculus, muscle bundle, myofibril
D*Fasciculus, muscle bundle, myofibril
2. All the following is correct facts about of Botulinum toxin except? A. The botulinum toxin, is produced by the bacteria Clostridium botulinum B. The botulinum toxin locks the release of ACh contained within the synaptic end bulb. C. The botulinum toxin symptoms are paralyzing the victim, stopping respiration, and leading to death. D. Cause blocking ACh receptors within the motor end plate of the muscle fiber.
D. *Cause blocking ACh receptors within the motor end plate of the muscle fiber
46.Which of the following correctly lists the sequence of structures that action potentials must move through to excite skeletal muscle contraction? A. sarcolemma, axon of neuron, T tubules B. T tubules, sarcolemma, myofilament C. muscle fiber, axon of neuron, myofibrils D. axon of neuron, sarcolemma, T tubules E. myofibrils, myofilaments, mitochondria
D. axon of neuron, sarcolemma, T tubules
95. The neurotransmitter sending chemical signals at neuromuscular junctions of skeletal muscle is a. actin b. myosin c. troponin d. acetylcholine e. cholinesterase
d. *acetylcholine
96. The membrane that carries the muscle fiber's electrical signal from the surface to the fiber's interior is the a. t-tubule (transverse tubule) b. SR (sarcoplasmic reticulum) c. CM (cell membrane) d. post-synaptic membrane
*a. t-tubule (transverse tubule)
94.. Skeletal muscles are bound to surrounding tissues and other muscles with a type of connective tissues called a. tendon b. endomysium c. ligament d. perimysium e. fascia
*a. tendon
100. Muscle fascicles are surrounded by a. epimysium b. perimysium c. endomysium d. fascia e. tendon
*b. perimysium
87. Which of the following muscle tissues are striated? I. skeletal II. cardiac III. smooth a. I only b. III only c. I and III
Skeletal, Cardiac
85. Why do your muscles shiver when you're cold? a. To prevent paralysis b. To generate heat c. To improve elasticity d. To increase excitability
b. To generate heat
59. Myoglobin ________. A. is a protein involved in the direct phosphorylation of ADP B. stores oxygen in muscle cells C. breaks down glycogen D. stores oxygen in muscle cells
B*stores oxygen in muscle cells
62.After several visits to the gym and serious "iron pumping" (strength training) you notice that your biceps have enlarged. Which one of the following has happened to your muscles? A. atrophy B. dystrophy C. hyperplasia D. heterotrophy E. Hypertrophy
E*Hypertrophy
61Which of the following is NOT a major function of muscle tissue? A. moving blood throughout the body B. generating heat through contractions C. stabilizing the movement of joints D. promoting movement of body structures E. Production of Vitamins.
E*Production of Vitamins.
98. Two abundant organelles in skeletal muscle are a. cilia and lysosomes b. ATP and glucose c. mitochondria and ATP d. myofibrils and mitochondria
*d. myofibrils and mitochondria
73. Curare is a naturally occurring compound that competitively binds to nicotinic acetylcholine receptors on muscle cells. Which of the following symptoms might be seen in a patient who has been exposed to curare? A. Diaphragmatic paralysis B. Cardiac arrest C. Excessive salivation D. Muscle spasticity
A*Diaphragmatic paralysis
68. What is the role of acetylcholine in calcium release? A. Stimulates cellular contraction by opening voltage-gated ion channels B. Stimulates postsynaptic acetylcholine receptors to release intracellular calcium C. Binds to sarcoplasmic reticulum, causing calcium release D. Binds to the T-tubules, causing calcium release
A*Stimulates cellular contraction by opening voltage-gated ion channels
74. Which of the following is accurate regarding Type I and Type II muscle fibers? A. Type I fibers store much of their energy as triglycerides, whereas Type II fibers store energy as ATP or creatine phosphate. B. Type I fibers are easily fatigued and are therefore intended for short bursts of activity C. Type I fibers employ anaerobic metabolism, whereas Type II fibers utilize aerobic metabolism D. Type I fibers are white, whereas Type II fibers are red
A*Type I fibers store much of their energy as triglycerides, whereas Type II fibers
58.A neuromuscular junction (NMJ) A. is the synapse of a motor neuron with a muscle fiber. B. includes the synaptic end bulbs of the muscle fiber. C. includes the motor endplates of the motor neuron. D. uses Na+ as a neurotransmitter. E. All of the above are correct.
A*is the synapse of a motor neuron with a muscle fiber.
52.The contractile organelles of a skeletal muscle fiber are thread-like structures called A. myofibrils. B. myoglobin. C. mitochondria. D. Z discs.
A*myofibrils.
63.The oxygen-binding protein found in muscle cells is ________. A. myoglobin B. hemoglobin C. ATP D. immunoglobin
A*myoglobin
77. Skeletal muscle has a system of T-tubules while smooth muscle does not. A. True B. False
A. *True
48.What produces the striations of a skeletal muscle cell? A. the arrangement of myofilaments B. the sarcoplasmic reticulum C. a difference in the thickness of the sarcolemma D. the T tubules
A. the arrangement of myofilaments
51.Muscle tissue has all of the following properties except ________. A. secretion B. extensibility C. excitability D. contractility
A.*secretion
44.Which of the following types of muscle tissue contract when excited by their own autorhythmic muscle fibers? A. cardiac muscle B. slow twitch oxidative skeletal muscle C. multi-unit smooth muscle D. fast twitch glycolytic skeletal muscle E. All of these choices are correct.
A.cardiac muscle
21What is the name given to one of the units that contract? A. sarcomere B. sarcolemma C. sarcoplasm D. fasciculus
Answer is A: A muscle fiber consists of many sections (sarcomeres) connected end to end that shorten (contract) as the thick and thin fi laments slide past each other.
12. Which is the largest of the structures in a muscle fi bre? A. myofibril B. myofilament C. myosin D. myopic
Answer is A: A myofibril extends the length of a muscle cell. A myofilament isshorter than a sarcomere, while myosin is a molecule in a thick myofilament.
32. What is the role of Ca ++ in the contraction of a muscle cell? A. Ca ++ binds to troponin to change its shape which reveals actin's binding site. B. Ca ++ attaches to the binding site of actin C. Ca ++ detaches from ATP as it forms ADP D. Ca ++ causes the myosin head to detach from the binding site of actin
Answer is A: Actin's binding site is covered until calcium causes it to be exposed.
37. What is the neurotransmitter that crosses the neuromuscular junction? A. Acetylcholine (ACh) B. Adrenalin (epinephrine) C. Noradrenalin (norepinephrine) D. Ca ++
Answer is A: All somatic motor neurons release ACh at their synapses with skeletal muscle fi bres, that is, at the neuromuscular junction.
29. Select the one INCORRECT statement about skeletal muscles A. An "agonist" opposes or reverses a particular movement B. A muscle's attachment point to a stationary bone is called its "origin". C. A skeletal muscle cell is a "syncytium". D. Muscles that immobilise a bone are called "fixators".
Answer is A: An antagonist opposes a movement. All other statements
14. Which statement below best describes the role of Ca ++ in muscle contraction? A. Ca ++ binds to troponin, thereby changing its shape to expose the binding site. B. Ca ++ causes ADP and inorganic phosphate to detach from the myosin crossbridge. C. Ca ++ attaches to the myosin head, causing it to disengage from its binding site. D. Ca ++ crosses the sarcolemma from the axon terminal which allows the E. action potential to propagate along the sarcolemma.
Answer is A: Ca attaches to troponin causing a shape change which shifts theattached tropomyosin away from binding sites of actin.
25. What is the role of calcium ions in muscle contraction? To A. bind to troponin, thus changing its shape and pulling it away from the actin molecule. B. cause the myosin cross-bridge to detach from its binding site. C. cause the action potential to propagate along the sarcolemma. D. bind with ADP during aerobic respiration to produce ATP to provide energy.
Answer is A: Calcium binds to troponin. All other choices are wrong statements.
6. Which of the following is the smallest structure within a muscle fiber? A. myosin B. myofi lament C. myofi bril D. sarcomere
Answer is A: Myosin is a molecule that makes up a thick myofi lament. Manythick and thin myofi laments make up a sarcomere. Many sarcomeres joined endto end form a myofi bril.
3. All of the following structures are part of a muscle cell except one. Which one? A. sarcoma B. sarcolemma C. sarcoplasm D. sarcoplasmic reticulum
Answer is A: Sarcoma refers to a malignant tumor (a cancer) of connective orother non-epithelial tissue (bones, muscles, tendons, cartilage, nerves, fat, andblood vessels).
26.Which of the following describes skeletal muscle? A. striated, voluntary, multinucleate, individually named. B. striated, branched, uninucleate, involuntary. C. not striated, uninucleate, voluntary, individually named. D. not striated, multinucleate, involuntary, with intercalated discs.
Answer is A: Skeletal muscle is striated and is not branched (cardiac muscle cells are branched).
2. Smooth muscle is different from skeletal muscle because smooth muscle A. is found in the walls of arteries B. can be voluntarily contracted C. has many nuclei in a cell D. has intercalated discs between cells
Answer is A: Smooth muscle occurs in the walls of tubes, whereas skeletal muscle does not.
4. During muscle cell contraction, what happens because of Ca ++ binding to troponin? A. The binding site on actin is uncovered. B. Acetylcholine (ACh) is released. C. The cross-bridge disengages from the thin fi lament. D. ATP hydrolyses to ADP.
Answer is A: Troponin causes tropomyosin (which covers he binding site of actin) to be shifted away.
35. What binds to troponin causing it to expose the binding site on actin to enable muscle cell contraction? A. Ca ++ (calcium) B. ACh (acetylcholine) C. PO 4 D. 2− (phosphate) E. ADP (adenosine diphosphate)
Answer is A: Troponin has a binding site for calcium
76. Which of the following statements concerning the structure of muscle tissue is not correct? A. Skeletal muscle and cardiac muscle are both striated B. Smooth muscle cells have no striations as they lack myosin filaments C. The spread of excitation through a skeletal muscle fiber is brought about by a system of T-tubules. D. The myofibrils of skeletal muscle are surrounded by the sarcoplasmic reticulum
Answer is B
5.Which of the following muscle cell structures is the longest? A. A myofi lament B. A myofi bril C. A sarcomere D. A troponin molecule
Answer is B: A muscle cell is a bundle of myofi brils. Myofi brils contain manysarcomeres joined end to end. Within sarcomeres are found (the shorter) thickand thin myofi laments.
20. Which of the following muscle structures is the largest? A. sarcomere B. fascicle C. myofi bril D. muscle fi bre
Answer is B: A muscle fascicle is a bundle of muscle fi bres (cells). Choice A & B are smaller than a cell.
38. What does aerobic respiration refer to? A. glycolysis in the cytoplasm in the absence of oxygen. B. oxidative phosphorylation in the mitochondria in the presence of oxygen. C. glycolysis in the liver in the presence of oxygen D. gluconeogenesis in the liver in the absence of oxygen
Answer is B: Respiration occurs in the mitochondria of a cell. The term aerobic refers to the presence of oxygen.
18. Which one of the following is NOT a characteristic of skeletal muscle? A. excitability B. autonomic innervation C. contractility D. extensibility
Answer is B: Skeletal muscle is voluntary so is innervated by the somatic nervous system, not the autonomic system
11. Which term is given to the unit of a myofibril that contracts?. A. sarcoplasm B. sarcomere C. sarcolemma D. sarcoplasmic reticulum
Answer is B: The contraction of a myofi bril is due to the shortening of its component sarcomeres.
28. Which of these events is necessary for the contraction of a muscle cell? A. the shortening of myosin molecules. B. the hydrolysis of ATP to ADP & HPO 4 2− in the myosin cross-bridge. C. Ca 2+ binding to tropomyosin causing it to change shape. D. the movement of Ca 2+ from the sarcoplasm into the sarcoplasmic reticulum.
Answer is B: The hydrolysis of ATP energises the cross-bridge. (myosin molecules do not get shorter; calcium binds to troponin, not tropomyosin; calcium returns to the SR after contraction).
24. Which statement about thick or thin myofi laments is CORRECT? A. Thick myofilaments contain the three proteins myosin, tropomyosin and troponin. B. Thin myofilaments contain the three proteins actin, tropomyosin and troponin. C. Thick myofilaments contain about 300 myosin molecules each of which has a binding site for a cross bridge. D. Thin myofilaments contain about 300 myosin molecules each of which has a cross bridge
Answer is B: Thin myofi laments contain these three proteins. Choices C & Dare wrong as myosin has a cross-bridge rather than a binding site.
27. Which list is in the correct order of DECREASING size? A. muscle fiber, sarcomere, myofilament, myofibril. B. muscle, fasciculus, muscle fi bre, myofibril. C. sarcomere, fasciculus, myofi bril, myofi lament. D. muscle, muscle fibre, myosin, myofibril.
Answer is B: myofibril consists of sarcomeres joined end to end; A myofibri contains many myofilaments; A myofibril is larger than a molecule of myosin.
19. What is the role of Ca ++ in muscle contraction? A. Ca causes an action potential to travel along the sarcolemma B. Ca binds to troponin changing its shape. C. Ca attaches to the binding site of myosin, energizing it. D. Ca engages with the binding site of actin causing the power stroke
Answer is B: the myosin head cannot attach to actin until its binding site is exposed. Ca causes this to happen.
8. What is a "sarcomere"? A. a cancer of connective tissue B. the cytoplasm of a muscle cell C. a section of a myofilament. D. the plasma membrane of a muscle cell.
Answer is C: A myofilament is a long line of sarcomeres joined end to end. Soone section of a myofilament is a sarcomere.
13.Which protein(s) are found in thin myofilaments? A. actin B. actin and tropomyosin C. actin, tropomyosin, and troponin D. actin, myosin, tropomyosin, and troponin
Answer is C: Actin is the major component of a thin fi lament. Tropomyosincovers the biding site, while troponin provides the mechanism for removingtropomyosin from the binding site.
10. By which term is a muscle that opposes or reverses a particular movement called? A. agonist B. synergist C. antagonist D. fixator
Answer is C: An agonist muscle performs the action, while the antagonist mustrelax (be stretched) while the action is being performed (and can reverse theaction of the agonist).
15. What characteristic of a smooth muscle cell distinguishes it from cardiac and from skeletal muscle? A. being branched B. being under involuntary control C. lack of striations D. being uninucleate
Answer is C: Both cardiac and skeletal muscle show striations when viewed under the microscope, but smooth muscle does not
16.What causes the myosin binding site of an actin molecule to be exposed? A. ATP attaching to the myosin cross-bridge B. a nerve impulse reaching the motor end plate of a motor nerve. C. calcium ions attaching to troponin D. acetylcholine crossing the neuromuscular junction
Answer is C: Ca causes a change of shape to the troponin molecule when theyattach. This causes troponin to wrench tropomyosin away from its resting position covering the binding site.
1. Of the events that lead to myofilaments sliding over each other, which of the following happens first? A. The myosin head engages with the binding site on actin B. Troponin changes shape and pulls on tropomyosin C. Calcium ions enter the cell cytoplasm D. ATP is hydrolyzed to ADP and inorganic phosphate
Answer is C: Ca must first enter the cytoplasm in order to bind with troponin.
Skeletal muscle cells have all of the following characteristics EXCEPT one. Which one? A. a neuromuscular junction crossed by ACh (acetyl choline) B. invaginations of sarcolemma called "T tubules". C. they are branched D. they are striated
Answer is C: Skeletal muscle cells are not branched (but cardiac muscle cells are).
30. Which of the following groupings of muscle type and their characteristics is INCORRECT? A. skeletal, striated, voluntary B. smooth, visceral, involuntary C. cardiac, striated, voluntary D. skeletal, striated, syncytium
Answer is C: cardiac muscle is not voluntary.
31. The part of a skeletal muscle cell that is able to contract is called A. sarcoplasm B. sarcolemma C. sarcomere D. sarcoplasmic reticulum
Answer is C: sarcomeres contain myofi laments that slide past each other as the sarcomere contracts.
23. Which of these events is necessary for the contraction of a muscle cell? A. the shortening of myofilaments. B. the conversion of ADP & HPO 4 C. 2− to ATP in the cross-bridge. D. Ca 2+ binding to troponin causesing it to change shape. E. the movement of ACh from the sarcolemma to the axon terminal.
Answer is C: the binding of calcium is essential.
84.Which of the following statements concerning the contraction of smooth muscle are correct? A. Smooth muscles are innervated by autonomic nerves B. Some smooth muscles may contract without an action potential C. Smooth muscle fibers have no specialized neuromuscular junctions D. The contraction of smooth muscle is regulated by calcium in the same manner as cardiac muscle.
Answer is D
33. The energy for muscle contraction is derived from the mechanisms below EXCEPT for one. Which one is NOT a method of producing ATP? A. anaerobic glycolysis. B. aerobic respiration. C. direct phosphorylation of ADP by creatinine phosphate. D. anaerobic digestion of lactic acid.
Answer is D: ATP is not produced from lactic acid - lactic acid is produced from pyruvic acid after glucose is anaerobically lysed into ATP and pyruvic acid.
22. The neurotransmitter that causes an action potential to occur in a muscle cell membrane is called: A. inorganic phosphate (HPO 42− ) B. adenosine diphosphate (ADP) C. calcium (Ca ++ ) D. acetylcholine (ACh)
Answer is D: Acetylcholine is the neurotransmitter. All somatic motor neurons release ACh at their synapses with skeletal muscle fi bres.
17. What is the source of most of the energy needed by muscles for physical activity that continues for longer than 30 or 40 minutes.? A. ATP stored in muscle fi bres. B. glycolysis of glucose in the cell cytoplasm C. ATP produced from creatine phosphate stored in muscle fi bres D. aerobic respiration of pyruvic acid in mitochondria
Answer is D: Choice A lasts for a few seconds only. Choice B can provideenergy for a couple of minutes. Choice C can provide energy for vigorousactivity lasting about 15 seconds.
34.What is the source of the ATP used by muscles for vigorous activity that may last for 10 to 15 seconds? A. glycolysis of glucose in the cell cytoplasm forms ATP. B. the ATP that is stored in muscle cells as ATP. C. aerobic respiration in the mitochondria produces the ATP D. creatinine phosphate in muscle and ADP react to form the required ATP.
Answer is D: Creatinine phosphate is used to "recharge" the ADP that forms from ATP when the cross-bridge is energized.
9. Smooth muscle cells may be described by which of the following? A. striated, voluntary, multinucleate B. not striated, voluntary, multinucleate C. striated, involuntary, uninucleate D. not striated, involuntary, uninucleate
Answer is D: Smooth muscle is not striated, and it is involuntary and has one nucleus.
31. Microscopically, muscle fibres contain parallel myofibrils. What are the units joined end to end within a myofibril called? A: A. myofilament B. motor unit C. myosin D. sarcomere
Answer is D: sarcomeres joined end to end, like train carriages, form a myofibril.
79. The muscle fibres of skeletal muscle are electrically coupled so that one nerve fibre can control the activity of several muscle fibers. A. True B. False
Answer is False
78.. All muscle cells contain actin and myosin. A. True B. False
Answer is True
56. A muscle that opposes, or reverses, a particular movement is a(n) ________. A. agonist B. antagonist C. fixator D. synergist
B*antagonist
82. The action potential of cardiac muscle fibers is initiated by action potentials in sympathetic nerve fibers. A. True B. False
B. *False
83 Which of the following statements concerning cardiac muscle is incorrect? A. The force of contraction is increased by circulating adrenaline correct B. Heart muscle contracts in response to action potentials in the autonomic nerve fibers incorrect C. The action potential is about 10-20 times as long as that of skeletal muscle correct D. All of the Ca2+ required for contraction enters cardiac myocyte from ECF and the sarcoplasmic reticulum
B. *Heart muscle contracts in response to action potentials in the autonomic nerve fibers incorrect
75. Which of the following is NOT innervated by the autonomic nervous system? A. Branching muscle cell B. Striated skeletal muscle cell C. Myocardial cell D. Intestinal muscle cell
B. *Striated skeletal muscle cell
47.When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods? A. relaxation period B. refractory period C. fatigue period D. latent period
B.refractory period
57. An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________. A. hydrolysis B. the electron transport chain C. glycolysis D. the citric acid cycle
C *glycolysis
71.What is an aponeurosis? A. A segment of muscle that is not attached to bone B. An area of smooth muscle in the abdomen C. A large, flat tendon that anchors muscle D. A group of neurons that innervate striated muscle cells
C*A large, flat tendon that anchors muscle
67.What is the role of tropomyosin in muscle contraction? A. To release troponin from tropomyosin, allowing myosin to bind to the actin filament B. To release calcium from the sarcoplasmic reticulum C. To prevent myosin from continuing to slide up the actin filament D. To aid in myosin 'cocking' on the actin filament
C*To prevent myosin from continuing to slide up the actin filament
65.This is the property of muscle that gives it the ability to stretch without damage. A. electrical excitability B. contractility C. extensibility D. elasticity E. thermogenesis
C*extensibility
55 Muscular atrophies A. is in increase in muscle mass due to increased numbers of myofibrils. B. is an increase in muscle mass due to increased numbers of myofibers. C. is a decrease in muscle mass due to loss of myofibrils. D. is the result of overuse of muscles. E. is always reversible, no matter what the cause.
C*is a decrease in muscle mass due to loss of myofibrils.
72. We would expect to find smooth muscle in all of the following EXCEPT: A. Pulmonary circulatory tissue B. Esophagus C. Small intestine D. Myocardial tissue
D *Myocardial tissue
70. The space between two Z lines constitutes the: A. Sarcolemma B. Sarcophagus C. Sarcoplasm D. Sarcomere
D*Sarcomere
53 Fatigued muscle cells that recover rapidly are the products of ________. A. slow exercise of short duration B. slow exercise of long duration C. intense exercise of long duration D. intense exercise of short duration
D*intense exercise of short duration
80.. Which of the following statements concerning the role of Ca2+ in the contraction of skeletal muscle is correct? A. The calcium for skeletal muscle contraction is derived from the sarcoplasmic reticulum. B. Ca2+ released from the sarcoplasmic reticulum is essential for the contraction of skeletal muscle C. A rise in intracellular Ca2+ allows actin to interact with myosin D. The tension of a skeletal muscle fiber is partly regulated by G proteins.
D. *The tension of a skeletal muscle fiber is partly regulated by G proteins.
90. The cells of muscles, myocytes, develop from ________. A. Endoderm. B. Chondrocytes. C. Fibrocytes. D. Myoblasts
D. Myoblasts
49.A period of sustained skeletal muscle contraction in which individual twitches cannot be detected is called A. unfused tetanus. B. muscle atrophy. C. flaccidity. D. fused tetanus.
D. fused tetanus.
43.Which of the following regions of a sarcomere contain thin filaments? A. I band B. A band C. H zone D. Both I band and A band. E. All of these answer choices are correct.
D.*Both I band and A band.
61.The term aponeurosis refers to ________. A. the rough endoplasmic reticulum B. a sheetlike indirect attachment to a skeletal element C. the bands of myofibrils D. the tropomyosin-troponin complex E. a sheetlike indirect attachment to a skeletal element
E*a sheetlike indirect attachment to a skeletal element
60.What is the most distinguishing characteristic of muscle tissue? A. the ability to transform chemical energy into mechanical energy B. the design of the fibers C. the diversity of activity of muscle tissue D. the ability to respond to nervous stimulation E. the ability to transform chemical energy into mechanical energy
E*the ability to transform chemical energy into mechanical energy
39.Which of the following proteins is used to reinforce the sarcolemma and to help transmit the tension generated by the sarcomeres to the tendons? A. troponin B. tropomyosin C. myosin D. actin E. dystrophin
E. dystrophin
50A brief contraction of all muscle fibers in a motor unit in response to a single action potential moving down the somatic motor neuron is known as A. isometric contraction. B. isotonic contraction. C. tetany. D. refractory period. E. twitch contraction.
E. twitch contraction.
101. Mini case 3 -Jhon is 22-year-old man, a college student, comes to the emergency department because of difficulty speaking and the inability to swallow for the past 2 hours. He says he recently returned from spending Thanksgiving at his grandparent's house, and yesterday had eaten a family favorite: home-canned asparagus prepared by his grandmother. He woke up this morning with feelings of nausea and had several episodes of vomiting and nonblood diarrhea. -He denies experiencing these symptoms previously and was in his usual state of excellent health before the onset of symptoms. As the interview goes on, he begins to noticeably slur his speech and appears more fatigued than he did upon arrival but remains lucid. Physical examination shows drooping eyelids and diplopia. QUESTION: 1. Which of the following is the most appropriate treatment? a. Botulinum antitoxin b. Amphotericin B c. Staphylococcus aureus enterotoxin toxoid d. Ampicillin
a. *Botulinum antitoxin
99. The hypertrophy of muscles is due to a. increased numbers of myofibrils and the increased amount of connective tissue in the muscle b. increased numbers of fibers inside the muscle c. increased numbers of both fibers and myofibrils inside the muscle d. increased storage of glucose, myoglobin, ATP and creatine phosphate in the muscle
d. increased storage of glucose, myoglobin, ATP and creatine phosphate in the muscle