Muscular
A muscle fiber will respond to a stimulus when that stimulus reaches the _____ level. A)threshold B)relaxation C)rigor mortis D)recruitment E)resting
A)
A stimulus either causes an action potential or it doesn't. This is called ________. A)an all-or-none response B)a graded response C)a latent period response D)a relative refractory response E)a local response
A)
An action potential ________. A)occurs when the local potential reaches threshold level B)is not propagated C)has no repolarization phase D)is an example of negative feedback E)can be of varying strengths depending on strength of the stimulus
A)
During depolarization of the plasma membrane, _________. A)sodium ions move rapidly into the cell B)potassium ions move rapidly out of the cell C)membrane permeability to sodium ions decreases D)the outside of the cell becomes positively charged relative to the inside E)sodium ions move rapidly out of the cell
A)
If at rest, the permeability of the plasma membrane to K+ were to increase, the resting membrane potential would _________________________. A)hyperpolarize B)depolarize C)repolarize D)stabilize
A)
If the permeability of the plasma membrane to K+ increases, the resting membrane potential difference _______. This is called _______. A)increases, hyper polarization B)increases, depolarization C)decreases, hyperpolarization D)decreases, depolarization
A)
In hyperpolarization _________. A)K+ ions tend to diffuse out of the cell B)the plasma membrane's permeability to K+ decreases C)the resting membrane potential moves closer to zero D)Na+ ions enter the cell in large numbers E)the resting membrane potential becomes more positive
A)
Predict the effect on the resting membrane potential (RMP) if extracellular concentration of sodium increases (a small to medium amount). A)The resting membrane is not very permeable to Na+, so there very little change in RMP. B)The resting membrane is very permeable to Na+, so there will likely be a depolarization. C)The resting membrane is very permeable to Na+, so there will likely be a hyperpolarization.
A)
66. When an action potential reaches the presynaptic terminal, A. calcium ions diffuse into the presynaptic terminal through voltage-gated ion channels. B. acetylcholine moves into the presynaptic terminal. C. a local potential is generated in the presynaptic terminal. D. ligand-gated ion channels in the presynaptic terminal are opened. E. nothing else happens.
A. calcium ions diffuse into the presynaptic terminal through voltage-gated ion channels.
43. The sarcolemma is the A. cell membrane of a muscle fiber. B. cytoplasm of muscle cells. C. structural and functional unit of the skeletal muscle cell. D. contractile thread that extends the length of the muscle fiber. E. protein strand composed of actin.
A. cell membrane of a muscle fiber.
93. A condition in which stimuli occur so rapidly that there are no intervening relaxations between contractions is called A. complete tetanus. B. incomplete tetanus. C. involuntary paralysis. D. all or none tetanus. E. treppe.
A. complete tetanus.
101. A proper definition of muscle tone is A. constant tension produced by muscles for long periods of time. B. a feeling of well-being following exercise. C. the ability of a muscle to maintain a contraction against an outside force. D. muscles contracting together. E. warm-up of muscle tissue.
A. constant tension produced by muscles for long periods of time.
4. The capacity of a muscle cell to shorten forcefully is known as A. contractility. B. excitability. C. extensibility. D. elasticity. E. flexibility.
A. contractility.
71. If sodium ions cannot enter a muscle fiber in response to a stimulus, A. contraction cannot occur. B. relaxation cannot occur. C. sodium ions will be released from the sarcoplasmic reticulum instead. D. the active sites are left exposed. E. the action potential travels into the muscle anyway.
A. contraction cannot occur.
114. Rigor mortis occurs after death because A. cross-bridges form but can't release. B. calcium is actively transported back to the sarcoplasmic reticulum. C. anaerobic respiration is occurring. D. myosin levels decline at death.
A. cross-bridges form but can't release.
68. Acetylcholine is released from the presynaptic terminal by the process of A. exocytosis. B. diffusion. C. phagocytosis. D. active transport. E. endocytosis.
A. exocytosis.
164. Cardiac muscle cells are like skeletal muscle cells in that they both A. have striations. B. depolarize as a result of sodium and calcium influxes. C. possess intercalated disks. D. lack sarcomeres. E. are multinucleated.
A. have striations.
91. Tetanus of a muscle is thought to be caused by A. high calcium ion concentrations in the sarcoplasm. B. the rapid movement of sodium ions back into the sarcoplasmic reticulum. C. an increase in stimulus strength. D. increased temperature in the active muscle. E. decreased amounts of calcium ions in muscle tissue.
A. high calcium ion concentrations in the sarcoplasm.
155. If the resting membrane potential becomes more negative, which of the following has occurred? A. hyperpolarization B. repolarization C. depolarization D. isopolarization E. hypopolarization
A. hyperpolarization
48. The electrical properties of cells are the result of A. ion concentration differences across the plasma membrane. B. receptor sites that are present on the plasma membrane. C. phosphorylation reactions within the cytoplasm. D. phospholipids in the cell membrane. E. None of these choices is correct.
A. ion concentration differences across the plasma membrane.
98. The refractory period A. is the time during which the tissue cannot respond again. B. results in complete and incomplete tetanus. C. is the condition in which the muscle fiber only partially relaxes between contractions. D. is the condition in which stimuli occur so rapidly that there are no intervening relaxations. E. is the constant tension produced by muscles for long periods of time.
A. is the time during which the tissue cannot respond again.
46. The length of the resting sarcomere is A. longer than the length of a contracted sarcomere. B. shorter than the length of a contracted sarcomere. C. the same length as a contracted sarcomere. D. the same length as the muscle fiber. E. the same length as the myofibril.
A. longer than the length of a contracted sarcomere.
62. The sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called A. neuromuscular junctions. B. sarcomeres. C. myofilaments. D. Z disks. E. cell body of neuron.
A. neuromuscular junctions.
58. An action potential A. occurs when the local potential reaches threshold level. B. is not propagated. C. has no repolarization phase. D. is an example of negative feedback. E. can be of varying strengths depending on strength of the stimulus.
A. occurs when the local potential reaches threshold level.
38. A sarcomere extends from A. one Z disk to an adjacent Z disk. B. one T tubule to the next T tubule. C. the middle of the I band to the middle of the A band. D. the H zone to the I band. E. the M line to the next M line.
A. one Z disk to an adjacent Z disk.
51. The outside of the resting plasma membrane is __________ relative to the inside of the resting plasma membrane. A. positively charged B. negatively charged C. electrically neutral D. recharged E. None of these choices is correct.
A. positively charged
9. Skeletal muscle fibers A. possess striations. B. can contract but are not extensible or excitable. C. do not require nerve innervation to contract. D. increase dramatically in number after birth. E. are found in the walls of the stomach.
A. possess striations.
13. Which type of muscle tissue is multinucleated? A. skeletal muscle B. smooth muscle C. cardiac muscle D. both skeletal and cardiac muscle E. both cardiac and smooth muscle
A. skeletal muscle
74. The sarcoplasmic reticulum A. stores calcium ions. B. shortens during muscle contraction. C. transmits nerve impulses to the myofibrils. D. connects adjacent sarcomeres. E. covers the muscle fiber.
A. stores calcium ions.
24. Endomysium is a delicate network of loose connective tissue that A. surrounds each muscle fiber. B. forms a sheath around a fasciculus. C. is composed of elastic fibers. D. separates individual muscles. E. penetrates muscle fibers.
A. surrounds each muscle fiber.
23. Fascia A. surrounds individual muscles. B. separates muscle fibers. C. connects muscles to bone. D. is a type of muscle tissue. E. is a type of nerve tissue.
A. surrounds individual muscles.
90. A sustained muscle contraction is known as A. tetanus B. tone C. treppe D. twitch E. paralysis
A. tetanus
29. Myosin is also known as the A. thick myofilament. B. thin myofilament. C. intermediate myofilament. D. short myofilament. E. sarcomere.
A. thick myofilament.
33. Which of the following is composed of myosin molecules? A. thick myofilaments B. I Bands C. Z disks D. sarcolemma E. tropomyosin
A. thick myofilaments
61. A muscle fiber will respond to a stimulus when that stimulus reaches the _____ level. A. threshold B. relaxation C. rigor mortis D. recruitment E. resting
A. threshold
3rd step of excitation
ACh diffuses across the synaptic cleft and binds to receptors on the sarcolemma
Relaxation step 15
ACh separates from the receptor and AChE breaks it down
ACh binds to _____________ opening on the post-synaptic membrane (skeletal muscle). This ligand-gated opening allows ________ to rush in to the cell and depolarize the muscle fiber, thereby creating a muscle action potential (MAP).
AChR, Na+
Excitation-Contraction Coupling step 7
AP's open voltage-gated ion channels in the T tubules which are linked to calcium channels in the terminal cisterns. Ca diffuses out of SR and into the sarcoplasm
contraction step 13
ATP binds to myosin head breaking the cross-bridge. ATP is hydrolyzed into ADP + P.
what energizes the myosin head?
ATP hydrolysis reaction
Excitation-Contraction Coupling step 6
Action potential spreads in all directions and also down the t tubules
5th step of excitation
Areas of sarcolemma next to the MEP have voltage-gated ion channels that open in response to EPP
A presynaptic neuron that increases the probability of an action potential occurring is called? A) Decremental B)Excitatory C)Inhibitory D)None of the above
B)
During the absolute refractory period, the cell _________. A)generates many local potentials B)is insensitive to further stimulation C)responds to even weak stimuli D)reverses the direction of the action potential E)is very sensitive
B)
During the depolarization phase of an action potential, the permeability of the membrane A)to K+ is greatly increased. B)to Na+ is greatly increased. C)to Ca2+ is greatly increased. D)is unchanged.
B)
If the ECF around a nerve cell is replaced with an isotonic saline solution that contains less potassium ions than the regular ECF, the result is ________. A)no resting membrane potential B)hyperpolarized membrane C)depolarized membrane D)a resting membrane potential that reaches its normal value
B)
If the charge difference across the plasma membrane is decreased, _________. A)the potential difference across the plasma membrane does not change B)the membrane potential is more positive C)the change is called hyper polarization D)negative proteins can leave the cell E)the membrane potential is more negative
B)
Ion channels that open in response to depolarization are called _________. A)ion-gated channels B)voltage-gated channels C)stimulation-gated channels D)potential-gated channels
B)
Physiologically, resting potential indicates that the charge inside of the neuron is _____ compared to the outside of the neuron. A)positive B)negative C)neutral D)changing E)none of the above
B)
The absolute refractory period assures ___________. A)prolonged depolarization during the action potential B)completion of repolarization before another action potential C)that no after-potential occurs D)reversal of the direction of propagation of the action potential E)that the stimulus is strong enough to elicit a response
B)
The minimum depolarization needed to open Na+ gates is called the ________. A)repolarization B)threshold C)refractory period D)All-or-none law.
B)
The plasma membrane of a neuron is more permeable to potassium ions because _______. A)of its positive electrical charge B)there are more K+ leak channels than Na+ leak channels C)protein molecules cannot exit through the cell membrane D)calcium ions block Na+ and Cl- channels E)there are more non-gated channels for Na+ than K+
B)
The resting membrane potential results when the tendency for _______ to diffuse out of the cell is balanced by their attraction to opposite charges inside the cell. A)Na+ B)K+ C)Cl- D)negatively charged proteins
B)
When the voltage of a plasma membrane shifts from +35mV towards 0 mV, we say the cell is _______. A)depolarizing B)repolarizing C)hyperpolarizing D)reaching the threshold E)exiting the threshold
B)
Which of the following events is NOT a characteristic of an action potential? A)The plasma membrane becomes highly permeable to sodium ions and depolarization results. B)As sodium ions enter, the inside of the plasma membrane becomes more negative. C)At the peak of depolarization, sodium channels begin to close and potassium channels open. D)In repolarization, potassium ions flow out of the cell. E)Action potentials occur according to the all-or-none principle.
B)
Which of these terms is correctly matched with its definition or description? A)depolarization: membrane potential becomes more negative B)hyperpolarization: membrane potential becomes more negative C)hypopolarization: membrane potential becomes more negative.
B)
76. Arrange the following list of biochemical events in the correct sequence. (1) An action potential is conducted deep into the muscle fiber by the T tubule. (2) Calcium ions bind to troponin. (3) The membranes of the sarcoplasmic reticulum become more permeable to calcium ions. (4) Calcium ions diffuse into the sarcoplasm around the myofibril. (5) The troponin-tropomyosin complex moves exposing active sites. A. 1, 5, 2, 3, 4 B. 1, 3, 4, 2, 5 C. 1, 2, 3, 4, 5 D. 1, 3, 2, 5, 4 E. 1, 4, 3, 2, 5
B. 1, 3, 4, 2, 5
37. The region of the sarcomere that contains both actin and myosin myofilaments is called the A. I band. B. A band. C. Z disk. D. H zone. E. M line.
B. A band.
88. Which of the following is true? A. Muscle fatigue has no influence on the force of contractions. B. A threshold stimulus will cause contraction of a muscle fiber. C. A subthreshold stimulus causes a muscle contraction. D. Motor units do not obey the "all or none" law. E. A threshold stimulus will not affect motor units.
B. A threshold stimulus will cause contraction of a muscle fiber.
45. Which of the following statements regarding the sliding filament model is false? A. Actin and myosin do not shorten during contraction. B. Both actin and myosin myofilaments shorten during contraction. C. The sarcomere shortens. D. The I band and H zones become narrower during contraction. E. The A band remains constant in length.
B. Both actin and myosin myofilaments shorten during contraction.
145. When comparing smooth and skeletal muscle cells, which of the following statements is true? A. Smooth muscle cells have striations. B. The myofilaments in smooth muscle do not form sarcomeres. C. Smooth muscle cells are larger than skeletal muscle cells. D. Smooth muscle has a lot of actin and myosin. E. Smooth muscle cells are multinucleated.
B. The myofilaments in smooth muscle do not form sarcomeres.
132. What is a triad? A. a protein found along the groove of the F-actin double helix B. a T tubule and two adjacent terminal cisternae C. the combination of myosin heads with active sites on actin molecules D. the movement of myosin head while attached to actin myofilament E. after exercise, the oxygen taken in that exceeds the oxygen required for resting metabolism
B. a T tubule and two adjacent terminal cisternae
105. An isotonic contraction is described as A. action potential frequency is high enough that no relaxation of muscle fibers occurs. B. a muscle produces constant tension during contraction. C. a muscle produces an increasing tension during contraction. D. a muscle produces increasing tension as it shortens. E. a muscle produces tension, but the length of the muscle is increasing.
B. a muscle produces constant tension during contraction.
34. The active sites to which cross-bridges attach are found on the A. sarcoplasmic reticulum. B. actin myofilaments. C. Z disks. D. T tubules. E. myosin myofilaments.
B. actin myofilaments.
67. Lack of acetylcholinesterase in the synaptic cleft would result in A. a decrease in acetylcholine production by the motor neuron. B. continuous stimulation of the postsynaptic membrane. C. rapid degradation of acetylcholine. D. relaxation of the muscle. E. continuous stimulation of the presynaptic membrane.
B. continuous stimulation of the postsynaptic membrane.
81. A drug that interferes with the active transport of calcium ions from the sarcoplasm back into the sarcoplasmic reticulum would result in A. relaxation of the muscle fiber. B. contraction with no relaxation. C. muscle hypertrophy. D. fibrosis of the muscle. E. an imbalance of blood calcium.
B. contraction with no relaxation.
41. Sarcoplasm is the A. cell membrane of a muscle fiber. B. cytoplasm of muscle cells. C. structural and functional unit of the skeletal muscle cell. D. contractile thread that extends the length of the muscle fiber. E. protein strand composed of actin or myosin.
B. cytoplasm of muscle cells.
65. Acetylcholine binds to a membrane bound receptor and causes ligand-gated sodium channels to open and results in A. hyperpolarization. B. depolarization. C. hypoplarization. D. no change in membrane potential. E. There is not enough information to predict the outcome.
B. depolarization.
147. In smooth muscle, most of the calcium needed for muscle contraction A. is in the dense bodies. B. enters from extracellular fluid. C. is attached to the intermediate filaments. D. must be activated by myosin kinase. E. is stored in the sarcoplasmic reticulum.
B. enters from extracellular fluid.
154. Functionally, smooth muscle A. is well adapted to anaerobic metabolism. B. exhibits autorhythmic contractions. C. contracts in response to slow increases in length. D. is unable to maintain tone. E. rapidly develops an oxygen debt.
B. exhibits autorhythmic contractions.
167. A child ingested an organophosphate poison used to kill insects. Soon the child's muscles began spastic contractions. Predict what occurred at the synaptic cleft. A. decreased release of acetylcholine from presynaptic neurons B. increased accumulation of acetylcholine in the synapse C. the poison binds to acetylcholine receptors and stimulates them D. increased breakdown of acetylcholine in the synaptic cleft E. Both increased accumulation of acetylcholine in the synapse and increased breakdown of acetylcholine in the synaptic cleft.
B. increased accumulation of acetylcholine in the synapse
92. Which of the following helps explain the increased tension seen in multiple wave summation? A. increased motor unit recruitment B. increased concentration of calcium ions around the myofibrils C. exposure of more active sites on myosin myofilaments D. the breakdown of elastic elements in the cell E. decreased stimulus frequency
B. increased concentration of calcium ions around the myofibrils
141. Muscle atrophy A. involves an increase in the number of muscle fibers. B. is characterized by a decrease in muscle size. C. results from aerobic exercise. D. causes an increase in blood flow to the affected muscle. E. is characterized by an increase in muscle size.
B. is characterized by a decrease in muscle size
22. A fasciculus A. is a bundle of reticular fibers. B. is surrounded by perimysium. C. is only found in smooth muscle. D. possesses an external lamina. E. is a bundle of collagen fibers.
B. is surrounded by perimysium.
21. Skeletal muscle develops from multinucleated cells called A. fascicles. B. myoblasts. C. myofibrils. D. myotomes. E. fasciculi.
B. myoblasts.
77. In excitation-contraction coupling, A. calcium ions must bind with myosin to expose active sites on actin. B. myosin heads bind to exposed active sites on actin. C. cross-bridges form between myosin heads and calcium ions. D. movement of the troponin-tropomyosin complex causes actin myofilaments to slide. E. ATP binds to actin myofilaments.
B. myosin heads bind to exposed active sites on actin.
78. When the myosin head flexes into a bend, pulling the actin filament along with it, this is called the A. action reaction. B. power stroke. C. recovery stroke. D. muscle tone. E. action potential.
B. power stroke.
69. Too much acetylcholinesterase causes A. continuous stimulation of the muscle fiber. B. rapid degradation of acetycholine. C. voltage-gated calcium ion channels opening in the presynaptic terminal. D. an increase in sodium uptake by the muscle fiber. E. exocytosis of synaptic vesicles.
B. rapid degradation of acetycholine.
99. Multiple wave summation A. is a time during which the tissue cannot respond again. B. results in complete and incomplete tetanus. C. is a condition in which the muscle fiber only partially relaxes between contractions. D. is a condition in which stimuli occur so rapidly that there are no intervening relaxations. E. is a constant tension produced by muscles for long periods of time.
B. results in complete and incomplete tetanus.
20. Hypertrophy of skeletal muscles from weight lifting is caused by an increase in the A. number of muscle fibers. B. size of muscle fibers. C. number of striations. D. number of nuclei within the muscle fibers. E. number of muscle cells.
B. size of muscle fibers.
89. Whole muscles can respond in a graded fashion to stimuli by varying A. the force of contraction of individual muscle fibers. B. the number of motor units recruited. C. the amplitude of the action potential. D. the frequency of stimulus. E. thresholds.
B. the number of motor units recruited.
52. The plasma membrane of an excitable cell is more permeable to potassium ions because A. of its positive electrical charge. B. there are more non-gated channels for K+ than Na+. C. protein molecules cannot exit through the cell membrane. D. calcium ions block Na+ and Cl- channels. E. there are more gated channels for K+.
B. there are more non-gated channels for K+ than Na+.
Relaxation step 18
Tropomyosin moves back into position which block the binding site
Excitation-Contraction Coupling step 9
Troponin-tropomyosin complex changes shape and exposes the binding sites on the actin filament
A postsynaptic neuron that is less likely to generate an action potential is called? A) Decremental B)Excitatory C)Inhibitory D)None of the above
C)
During an action potential _______. A)Na+ efflux causes depolarization B)K+ influx causes repolarization C)Na+ influx causes depolarization D)K+ influx causes after-hyperpolarization
C)
Leak ion channels A)open in response to small voltage changes. B)open when a chemical signal binds to its receptor. C)are responsible for the ion permeability of the resting plasma membrane. D)allow substances to move into the cell but not out. E)All of these are correct.
C)
Opening of sodium gates typically leads to ________. A)repolarization of the plasma membrane B)hyperpolarization of the plasma membrane C)depolarization of the plasma membrane D)drifting of plasma membrane voltage toward a more negative value E)plasma membrane voltage returning to the resting membrane potential
C)
The major function of the sodium-potassium pump is to A)pump Na+ into and K+ out of the cell. B)generate the resting membrane potential. C)maintain the concentration gradients of Na+ and K+ across the plasma membrane. D)oppose any tendency of the cell to undergo hyperpolarization.
C)
The membrane of resting nerve cells is more permeable to ____________ ions than ____________ ions. A)sodium, potassium B)calcium, potassium C)potassium, sodium D)chloride, potassium
C)
Which of the following situations occurs in electrically excitable cells? A)When Na+ ion channels open, K+ ion channels close. B)The sodium-potassium exchange pump moves sodium into the cell. C)Depolarization causes voltage-gated sodium ion channels to open. D)Ligand-gated sodium ion channels are opened by high extracellular calcium levels. E)Proteins tend to diffuse out of the cell.
C)
Which of the following statements accurately describe events that could occur as a result of a local potential reaching threshold? A)Activation gates of Na+ ion channels begin to close. B)Inactivation gates of Na+ ion channels begin to open. C)A positive feedback cycle develops in which depolarization of one portion of the membrane causes activation gates of Na+ ion channels nearby to open. D)voltage gated K+ ion channels begin to close.
C)
56. Which of the following situations occurs in electrically excitable cells? A. When Na+ ion channels open, K+ ion channels close. B. The sodium-potassium pump moves sodium into the cell. C. Depolarization causes voltage-gated sodium ion channels to open. D. Sodium ion channels are opened by high extracellular calcium levels. E. The opening and closing of ligand-gated channels cause depolarization.
C. Depolarization causes voltage-gated sodium ion channels to open.
110. Which of the following is true? A. The greater the overlap of actin and myosin, the stronger the contraction. B. Overstretching a muscle will increase its tension. C. Optimal actin and myosin overlap will produce maximal contraction. D. The greatest amount of tension is achieved when actin and myosin do not overlap. E. Tension is great when actin and myosin overlap as much as they can.
C. Optimal actin and myosin overlap will produce maximal contraction.
84. Which of the following events occurs during the lag phase of a muscle twitch? A. Muscle fibers shorten. B. Cross-bridges form, move, release, and reform many times. C. The action potential is propagated from presynaptic to postsynaptic terminal. D. Calcium is pumped back into the sarcoplasmic reticulum. E. All of these events occur in the lag phase.
C. The action potential is propagated from presynaptic to postsynaptic terminal.
36. Which of the following is NOT a property of the myosin head? A. They form cross-bridges with the active sites of actin. B. They have a hinge region to bend and straighten. C. They bind to troponin. D. They have ATPase activity. E. They bind to ATP
C. They bind to troponin.
108. An isometric contraction is described as A. action potential frequency is high enough that no relaxation of muscle fibers occurs. B. a muscle produces constant tension during contraction. C. a muscle produces an increasing tension as the length remains constant. D. a muscle produces increasing tension as it shortens. E. a muscle produces tension, but the length of the muscle is increasing
C. a muscle produces an increasing tension as the length remains constant.
63. Synaptic vesicles in the neuromuscular junction contain A. calcium. B. ATP. C. acetylcholine. D. acetylcholinesterase. E. sodium.
C. acetylcholine.
83. During the contraction phase of a muscle twitch, A. acetylcholine stimulates the pre-synaptic terminal. B. sodium ions diffuse into the muscle fiber. C. actin-myosin cross-bridges form. D. calcium ions are transported back to the sarcoplasmic reticulum. E. the action potential travels down the T tubule.
C. actin-myosin cross-bridges form.
134. Which of the following correctly describes myoglobin's special function in muscle tissue? A. breaks down glycogen B. synthesizes ATP C. acts as a reservoir for oxygen D. produces action potentials E. stores glucose
C. acts as a reservoir for oxygen
73. T tubules A. provide nutrients to the muscle fiber. B. generate new muscle fibers. C. conduct action potentials deep into the muscle cell. D. release acetylcholine. E. store calcium ions.
C. conduct action potentials deep into the muscle cell.
28. Muscle myofibrils A. are found in the sarcolemma. B. extend from the sarcolemma to the T-tubule. C. contain myosin and actin myofilaments. D. hold muscle cells together. E. do not appear striated.
C. contain myosin and actin myofilaments.
25. Which of the following connective tissue layers is outside all the others? A. perimysium B. endomysium C. epimysium D. paramysium E. sarcolemma
C. epimysium
96. Incomplete tetanus A. is the time during which the tissue cannot respond again. B. results in complete and incomplete tetanus. C. is the condition in which the muscle fiber only partially relaxes between contractions. D. is the condition in which stimuli occur so rapidly that there are no intervening relaxations. E. is the constant tension produced by muscles for long periods of time.
C. is the condition in which the muscle fiber only partially relaxes between contractions.
85. The time between application of the stimulus to a motor neuron and the beginning of contraction is called the _____ phase. A. contraction B. relaxation C. latent or lag D. refractory E. threshold
C. latent or lag
95. The stretch of elastic components of a muscle adds to the increased tension during A. incomplete tetanus. B. twitch. C. multiple wave summation. D. all or none response. E. none of these.
C. multiple wave summation.
35. ATPase is found in A. F-actin strands. B. G-actin globular units. C. myosin heads. D. tropomyosin grooves. E. troponin molecules.
C. myosin heads.
75. Arrange these structures as they participate in excitation-contraction. A. T tubules, sarcolemma, calcium ions, sarcoplasmic reticulum B. calcium ions, T tubules, sarcolemma, sarcoplasmic reticulum C. sarcolemma, T tubules, sarcoplasmic reticulum, calcium ions D. sarcoplasmic reticulum, calcium ions, T tubules, sarcolemma E. sarcolemma, sarcoplasmic reticulum, calcium ions, T tubules
C. sarcolemma, T tubules, sarcoplasmic reticulum, calcium ions
47. The model that describes the contraction of the muscle is called the A. contraction cycle. B. power stroke. C. sliding filament model. D. slipping fibril mechanism. E. paddle model.
C. sliding filament model.
80. In order for muscle relaxation to occur, A. calcium ions must be transported to troponin. B. power strokes slow down. C. the active sites on actin must be blocked. D. sodium ions must be actively transported to troponin. E. the active sites on myosin must be uncovered.
C. the active sites on actin must be blocked.
129. What is a cross-bridge? A. a protein found along the groove of the F-actin double helix B. a T tubule and two adjacent terminal cisternae C. the combination of myosin heads with active sites on actin molecules D. the movement of myosin head while attached to actin myofilament E. after exercise, the oxygen taken in that exceeds the oxygen required for resting metabolism
C. the combination of myosin heads with active sites on actin molecules
Excitation-Contraction Coupling step 8
Ca binds with troponin of the thin filaments
Relaxation step 17
Ca levels in sarcoplasm decreases which causes Ca to dissociate from the troponin
2nd step of excitation
Ca stimulates the synaptic vesicles to release ACh
A neuron repolarizes by ________ after it has been stimulated. A)producing ATP B)the generation of a second impulse C)growing a myelin sheath D)the outward movement of potassium ions (K+) E)generating an impulse in the opposite direction
D)
Channels that open or close in response to changes in the electrical charge or voltage across the plasma membrane are called _________ A)ligand-gated ion channels. B)non-gated ion channels. C)relegated ion channels. D)voltage-gated ion channels. E)obligated ion channels.
D)
Concerning concentration differences across the plasma membrane, there are A)more K+ and Na+ outside the cell than inside. B)more K+ and Na+ inside the cell than outside. C)more K+ outside the cell than inside and more Na+ inside the cell than outside. D)more K+ inside the cell than outside and more Na+ outside the cell than inside.
D)
Depolarization of the cell membrane occurs when there is a rapid influx (inflow) of _______ A)potassium ions. B)chloride ions. C)calcium ions. D)sodium ions. E)amino acids.
D)
Depolarization of the nerve cell membrane occurs when there is a rapid influx (inflow) of _________. A)potassium ions B)chloride ions C)calcium ions D)sodium ions E)proteins
D)
During hyperpolarization (or afterpotential) _______. A)sodium ions are entering the cells B)sodium ions are leaving the cell C)potassium ions are entering the cell D)potassium ions are leaving the cell E)both sodium and potassium ions are leaving the cell
D)
During repolarization of the plasma membrane, A)Na+ diffuse into the cell. B)Na+ diffuse out of the cell. C)K+ diffuse into the cell. D)K+ diffuse out of the cell.
D)
For the resting membrane potential, increasing the sodium ion concentration in the ECF results in ________. A)hyperpolarization B)depolarization C)hypopolarization D)little change in membrane potential E)There is not enough information to determine the results.
D)
The absolute refractory period A)limits how many action potentials can be produced during a given period of time. B)prevents an action potential from starting another action potential at the same point on the plasma membrane. C)is the period of time when a strong stimulus can initiate a second action potential. D)Both a and b are correct. E)All of these are correct.
D)
The period of time when Na+ channels are recovering from their inactive state and K+ channels are still open is the _________. A)repolarization. B)absolute refractory period. C)relative refractory period. D)Both repolarization and relative refractory period are correct.
D)
When repolarization of a neuron is complete, the __________. A)neuron dies B)neuron regenerates C)cell no longer has a potential difference across its membrane D)original polarity of the neuron is restored E)neuron is no longer excitable
D)
Which of the following is true during the resting membrane potential? A)Sodium ion concentration is greater inside cells. B)Negatively charged proteins are more concentrated outside the cell. C)A greater concentration of calcium ions is found inside the cell. D)Potassium is concentrated primarily inside the cell. E)None of these choices reflect what occurs during the resting membrane potential.
D)
Which of the following statements about action potentials are correct? A)The rising phase of the action potential is due to a rapid increase in the permeability to Na+. B)The threshold can be reached in response to a decrease in K+ permeability. C)There is a decrease in Na+ permeability and an increase in K+ permeability during the repolarization phase of the action potential. D)All of the above are correct
D)
27. List the following structures in order from smallest to largest. (1) muscle fiber (2) myofilament (3) myofibril (4) muscle fasciculus A. 4, 2, 3, 1 B. 2, 1, 4, 3 C. 3, 1, 4, 2 D. 2, 3, 1, 4 E. 1, 2, 3, 4
D. 2, 3, 1, 4
50. Which of the following is true during the resting membrane potential? A. Sodium ion concentration is greater inside cells. B. Negatively charged proteins are more concentrated outside the cell. C. A greater concentration of calcium ions is found inside the cell. D. Potassium is concentrated primarily inside the cell. E. None of these choices reflect what occurs during the resting membrane potential.
D. Potassium is concentrated primarily inside the cell.
87. Which of the following will respond to a threshold stimulus with an all-or-none contraction? A. a single muscle fiber B. a single motor unit C. a whole muscle D. a single muscle fiber and a single motor unit E. a single muscle fiber, a single motor unit, and a whole muscle
D. a single muscle fiber and a single motor unit
11. Which type of muscle tissue possesses striations? A. skeletal muscle B. smooth muscle C. cardiac muscle D. both skeletal and cardiac muscle E. both cardiac and smooth muscle
D. both skeletal and cardiac muscle
1. Which of the following is NOT a function of skeletal muscle? A. body movement B. maintenance of posture C. respiration D. constriction of organs E. production of heat
D. constriction of organs
30. Actin myofilaments A. resemble bundles of minute golf clubs. B. contain both myosin and tropomyosin. C. are held in place by the M line. D. contain strands of fibrous actin. E. are the thickest proteins in muscle.
D. contain strands of fibrous actin.
44. A myofibril is the A. cell membrane of a muscle fiber. B. cytoplasm of muscle cells. C. structural and functional unit of the skeletal muscle cell. D. contractile thread that extends the length of the muscle fiber. E. protein strand composed of actin.
D. contractile thread that extends the length of the muscle fiber.
32. Troponin A. has two subunits. B. is part of the myosin myofilament. C. is a long, flexible protein. D. has a calcium-binding site. E. binds to ATP.
D. has a calcium-binding site.
166. Curare blocks acetylcholine receptors at the motor end plate. This would result in A. increased stimulation of the muscle. B. more acetylcholinesterase production. C. lack of calcium uptake by the muscle fiber. D. inability of the muscle fiber to respond to nervous stimulation. E. sustained contraction of the muscle.
D. inability of the muscle fiber to respond to nervous stimulation.
55. Which of the following changes have the potential to dramatically affect the potential difference across the plasma membrane? A. increased permeability of the membrane to sodium ions B. increased intracellular concentration of potassium ions C. any change in the rate at which the sodium-potassium pump works D. increased permeability of the membrane to sodium ions and increased intracellular concentration of potassium ions E. increased permeability of the membrane to sodium ions, increased intracellular concentration of potassium ions and any change in the rate at which the sodium-potassium pump works
D. increased permeability of the membrane to sodium ions and increased intracellular concentration of potassium ions
100. Complete tetanus A. is the time during which the tissue cannot respond again. B. results in complete and incomplete tetanus. C. is the condition in which the muscle fiber only partially relaxes between contractions. D. is the condition in which stimuli occur so rapidly that there are no intervening relaxations. E. is the constant tension produced by muscles for long periods of time.
D. is the condition in which stimuli occur so rapidly that there are no intervening relaxations.
39. Which of the following is mismatched? A. I band - contains only actin B. M line - middle of the H zone C. Z disk - structure between adjacent sarcomeres D. myosin myofilaments - thin myofilaments E. actin myofilaments - thin myofilaments
D. myosin myofilaments - thin myofilaments
64. Which of the following structures contains the other four items listed? A. postsynaptic membrane B. presynaptic terminal C. synaptic cleft D. neuromuscular junction E. receptors on postsynaptic membrane
D. neuromuscular junction
70. Which of the following events occurs on the postsynaptic membrane? A. acetylcholine production B. rapid degradation of acetylcholine C. release of neurotransmitter D. neurotransmitter combines with a receptor molecule E. release of calcium ions
D. neurotransmitter combines with a receptor molecule
82. After contraction has occurred, the calcium is A. destroyed by cholinesterase. B. chemically bound to the cross bridges. C. secreted by the Golgi apparatus to the outside of the cell. D. released from troponin. E. returned to the sarcolemma.
D. released from troponin.
5. Muscles exhibit the property of excitability. This means that the muscle A. shortens its length. B. recoils to its original resting length. C. stretches beyond its normal length. D. responds to stimulation by the nervous system. E. excites itself.
D. responds to stimulation by the nervous system.
57. Depolarization of the cell membrane occurs when there is a rapid influx (inflow) of A. potassium ions. B. chloride ions. C. calcium ions. D. sodium ions. E. amino acids.
D. sodium ions.
130. What is the power stroke? A. a protein found along the groove of the F-actin double helix B. a T tubule and two adjacent terminal cisternae C. the combination of myosin heads with active sites on actin molecules D. the movement of myosin head while attached to actin myofilament E. after exercise, the oxygen taken in that exceeds the oxygen required
D. the movement of myosin head while attached to actin myofilament
86. Which of the following would occur as a result of a single muscle contraction? A. tetanus B. tone C. treppe D. twitch E. paralysis
D. twitch
54. Channels that open or close in response to changes in the electrical charge or voltage across the plasma membrane are called A. ligand-gated ion channels. B. non-gated ion channels. C. relegated ion channels. D. voltage-gated ion channels. E. obligated ion channels.
D. voltage-gated ion channels.
Relaxation step 16
During excitation through contraction, SR releases and reabsorbs Ca. When the nerve fiber stops, Ca release also stops but reabsorption continues
7. During the absolute refractory period _______. A)if a neuron reaches threshold, the action potential goes to completion B)the neuron fires at its maximum voltage if a stimulus depolarizes the neuron to threshold C)the signal grows weaker with distance D)it is possible to trigger a new action potential, but only with an unusually strong stimulus E)no stimulus of any strength will trigger a new action potential
E)
In nerve physiology, the time soon after an action potential has moved on and the sodium gates are unable to open is called the __________. A)refraction period B)latent period C)treppe D)action potential period E)refractory period
E)
The relative refractory period assures ___________. A)prolonged depolarization during the action potential B)completion of repolarization before another action potential C)that no after-potential occurs D)reversal of the direction of propagation of the action potential E)that the stimulus is strong enough to elicit a response
E)
When a neuron is excited: A)positive charges move in B)the nerve fiber becomes depolarized C)an impulse begins to flow D)the nerve cell membrane becomes permeable to sodium E)All of the choices are correct.
E)
Which of the following situations will lead to hyperpolarization? A)Increase the permeability of the plasma membrane to Na+ ions. B)Decrease the permeability of the plasma membrane to K+ ions. C)Decrease the permeability of the plasma membrane to chloride ions. D)Any positive ion entering the cell. E)None of these situations will lead to hyperpolarization.
E)
___ has the greatest influence on the resting membrane potential. A)Sodium B)Chloride C)Calcium D)Phosphate E)Potassium
E)
94. Treppe A. can contribute to improved muscle efficiency. B. may be due to an increase in the level of calcium ions around the myofibril. C. is an example of a graded response. D. is achieved during warm-up exercises. E. All of these choices are correct.
E. All of these choices are correct.
12. Which type of muscle tissue is autorhythmic? A. skeletal muscle B. smooth muscle C. cardiac muscle D. both skeletal and cardiac muscle E. both cardiac and smooth muscle
E. both cardiac and smooth muscle
79. One ATP molecule is required for A. formation of the cross-bridge. B. movement of the cross-bridge. C. release of the cross-bridge. D. formation of the cross-bridge and for movement of the cross-bridge. E. formation of the cross-bridge, for movement of the cross-bridge, and for release of the cross-bridge.
E. formation of the cross-bridge, for movement of the cross-bridge, and for release of the cross-bridge.
97. Muscle tone A. is a time during which the tissue cannot respond again. B. results in complete and incomplete tetanus. C. is a condition in which the muscle fiber only partially relaxes between contractions. D. is a condition in which stimuli occur so rapidly that there are no intervening relaxations. E. is a constant tension produced by muscles for long periods of time.
E. is a constant tension produced by muscles for long periods of time.
60. When repolarization of the cell membrane is complete, the A. cell dies. B. cell regenerates. C. cell no longer has a potential difference across its membrane. D. cell is no longer responsive. E. original polarity of the cell is restored.
E. original polarity of the cell is restored.
42. A myofilament is the A. cell membrane of a muscle fiber. B. cytoplasm of muscle cells. C. structural and functional unit of the skeletal muscle cell. D. contractile thread that extends the length of the muscle fiber. E. protein strand composed of actin or myosin
E. protein strand composed of actin or myosin
72. T tubules are invaginations of the A. sarcoplasmic reticulum. B. sarcomere. C. myofibril. D. sarcoplasm. E. sarcolemma.
E. sarcolemma.
end-plate potential (EPP)
When channel opens, Na flows into the cell and K flows out The voltage of the sarcolemma becomes less negative as Na enters and returns to RMP as K exits.
predict the consequences of administration of a compound that blocks the calcium channels on presynaptic terminals.
It would prevent the diffusion of calcium ions into the presynaptic terminal. It could result in failure for action potential to occur.
Contraction step 10
Myosin head must have ATP to initiate contraction. Myosin ATPase hydrolizes ATP into ADP + P - This "cocks" the head into an extended, high-energy position
Contraction step 12
Myosin releases the ADP + P and the head flexes into a low-energy position pulling the actin filament. This is called the power stroke -Head remains bound to actin until another ATP comes along
First step of excitation
Nerve signal arrives at the axon terminal and opens voltage-gated Ca channels and Ca enters the terminal
Relaxation step 14
Nerve signals stop arriving at the NMJ which stops the release of ACh
the distribution of muscle fibers tends to be constant for each individual. Consider the following distributions: Type 1 fibers TYPE 2 person A: 30% 70% person B: 65% 35% person C: 55%. 45% which person is more likely to be a sprinter?
Person A
what is the purpose of the triad?
The triad allows for Ca2+ release when a muscle fiber is excited.
What is AChE
acetylcholinesterase
Myosin heads swivel upward and bind ______ and cycles through the "power stroke"
actin
Power stroke
action of myosin pulling actin inward (toward the M line)
the neural _______ arrives at axon terminal
action potential
Excitation-Contraction Coupling
action potentials spread in all directions
A drug completely blocks Na+ channels in nerves. Which of the following effects on the action potential would it be expected to produce?
block the occurance of action potential.
during the contraction phase a muscle twitch
calcium ions are transported back to the sarcoplasmic reticulum.
Actin myofilaments
contain strands of fibrous actin.
Lack of acetylcholinesterase in the synaptic cleft would result in
continuous stimulation of the postsynaptic membrane.
neurotransmitter release occurs by what mechanism?
exocytosis
if the resting membrane potential becomes more negative, which of the following has occurred?
hyper polarization
Mr. Miller has been hospitalized for the flu. The flu virus increases membrane permeability to potassium. You would expect his cells to
hyperpolarize.
Curare blocks acetylcholine receptors at the motor end plate. This would result in
inability of the muscle fiber to respond to nervous stimulation.
Acetylocholine
is composed of acetic acid and choline & is a neurotransmitter
complete tetanus
is the condition in which stimuli occur so rapidly that there are no intervening relaxations.
The term for shortening of a muscle while maintaining constant tension is
isotonic contraction
For the resting membrane potential, increasing the sodium ion concentration in the ECF results in
little change in membrane potential
Action potential
movement of electrical charge over the membrane from channel to channel
when repolarization of the cell membrane is complete, the
original polarity of the cell is restored.
attack of motor neurons in the central nervous system (brain and spinal cord) would lead to paralysis. This is how ________ occurs.
polio
which of the following is true during the resting membrane potential?
potassium is concentrated primarily inside the cell.
Excitation
process in which nerve action potentials lead to muscle action potentials(application of energy)
The MAP travels down the muscle membrane, or the __________
sarcolemma
Arrange these structures as they participate in excitation-contraction.
sarcolemma, t-tubules, sarcoplasmic reticulum, calcium ions
The MAP triggers voltage-sensitive Ca2+ channels on the terminal cisternae of the ____________ to open. Ca2+ is released from this muscle-specific organelle.
sarcoplasmic reticulum
which muscle type depends solely on the sarcoplasmic reticulum as it's calcium source?
skeletal and cardiac muscle
predict the effect on the resting membrane potential if permeability of cell membrane to sodium ions increases.
sodium ion diffuse into the cell and inside of the cell becomes more positive resulting in depolarization.
Endomysium is a delicate network of loose connective tissue that
surrounds each muscle fiber
ACh is released into the __________ ___________
synaptic cleft
The advantage of having many nuclei in a skeletal muscle fiber is
the ability to produce large amounts of the muscle proteins needed for muscle contraction.
an important characteristic of smooth muscle is that
the major source of calcium is in the extracellular fluid.
the plasma membrane of a neuron is more permeable to potassium ions because
there are more non-gated channels for K+ than Na+
which of the following is NOT a property of the myosin head?
they bind to troponin.
which statement best describes the goal of medications used to treat myasthenia gravis?
to increase the number of acetylcholine receptors.
MAP travels down _________ tubules
tranverse (T)
Troponin moves the ________ exposing the myosin binding site on actin
tropomyosin
Ca2+ binds to _____________ located on the actin filament
troponin C
Channels that open or close in response to a chemical binding to the channel are called
voltage gated ion channels
Z disc
where thin filaments are anchored.
Predict the effect on the resting membrane potential if concentration of potassium ions in the extracellular fluid increases. A)The increased extracellular potassium concentration decreases the normal potassium ion gradient. As a result, there is less of a tendency for potassium ions to diffuse out of the cell and the RMP is less negative; that is, it depolarizes. B)The increased extracellular potassium concentration increases the normal potassium ion gradient. As a result, there is more of a tendency for potassium ions to diffuse out of the cell and the RMP is more negative; that is, it hyperpolarizes. C)The increased extracellular potassium concentration decreases the normal potassium ion gradient. As a result, there is less of a tendency for potassium ions to diffuse out of the cell and the RMP is less negative; that is, it hyperpolarizes. D)The increased extracellular potassium concentration increases the normal potassium ion gradient. As a result, there is more of a tendency for potassium ions to diffuse out of the cell and the RMP is less negative; that is, it depolarizes.
A)
Predict the effect on the resting membrane potential if permeability of cell membrane to sodium ions increases. A)When the permeability to sodium ions increases, the sodium ions diffuse into the cell and the inside of the cell becomes more positive, resulting in depolarization. B)When the permeability to sodium ions increases, the sodium ions diffuse out of the cell and the inside of the cell becomes more negative, resulting in depolarization. C)When the permeability to sodium ions increases, the sodium ions diffuse out of the cell and the inside of the cell becomes more positive, resulting in hyperpolarization. D)When the permeability to sodium ions increases, the sodium ions diffuse into the cell and the inside of the cell becomes more negative, resulting in hyperpolarization.
A)
The electrical properties of cells are the result of ________ A)ion concentration differences across the plasma membrane. B)receptor sites that are present on the plasma membrane. C)phosphorylation reactions within the cytoplasm. D)phospholipids in the cell membrane. E)None of these choices is correct.
A)
The outside of the resting plasma membrane is __________ relative to the inside of the resting plasma membrane. A)positively charged B)negatively charged C)electrically neutral D)recharged E)None of these choices is correct
A)
The very brief moment following stimulation when a muscle remains unresponsive to additional stimulation is called the ________. A)refractory period B)relaxation period C)latent period D)contraction period E)refractory index
A)
why is the refractory periods important? A)helps the action potential move in one direction B)helps the action potential to move in both directions C) A andB D) none of the above
A)
103. Which of the following statements concerning types of muscle contractions is false? A. In isometric contractions, the amount of tension produced by the muscle is constant. B. In isotonic contractions, the muscle fibers shorten. C. The contractile processes in isometric and isotonic contractions are the same. D. Most skeletal muscle contractions are a combination of isometric and isotonic contractions. E. In isotonic contractions, the amount of tension produced by the muscle fibers is constant during the contraction.
A. In isometric contractions, the amount of tension produced by the muscle is constant.
6. Identify the statement concerning general functional characteristics of muscle that is true. A. Muscle tissue shortens forcefully but lengthens passively. B. Muscle tissue shortens passively but lengthens forcefully. C. Muscle tissue can get shorter, but can not get longer. D. Muscle tissue can get longer, but can not get shorter. E. None of these statements are true.
A. Muscle tissue shortens forcefully but lengthens passively.
131. What is tropomyosin? A. a protein found along the groove of the F-actin double helix B. a T tubule and two adjacent terminal cisternae C. the combination of myosin heads with active sites on actin molecules D. the movement of myosin head while attached to actin myofilament E. after exercise, the oxygen taken in that exceeds the oxygen required for resting metabolism
A. a protein found along the groove of the F-actin double helix
53. In which of the following situations does a resting membrane potential exist? A. a relaxed muscle fiber B. a conducting neuron C. a stimulated sensory receptor in the skin D. a contracting cardiac muscle cell E. the eye seeing an image
A. a relaxed muscle fiber
106. Tetanus of muscles is described as A. action potential frequency is high enough that no relaxation of muscle fibers occurs. B. a muscle produces constant tension during contraction. C. a muscle produces an increasing tension during contraction. D. a muscle produces increasing tension as it shortens. E. a muscle produces tension, but the length of the muscle is increasing.
A. action potential frequency is high enough that no relaxation of muscle fibers occurs.
59. A stimulus either causes an action potential or it doesn't. This is called A. an all-or-none response. B. a graded response. C. a latent period response. D. a relative refractory response. E. an arbitrary response.
A. an all-or-none response.
3. Smooth muscle and cardiac muscle are similar in that they both A. are under involuntary control. B. are striated. C. are widely distributed in the body. D. have multiple nuclei. E. are under voluntary control.
A. are under involuntary control.
4th step of excitation
Each receptor binds to two ACh molecules to open the channel
Contraction step 11
The cocked head binds to the exposed binding site on the actin filament forming a cross-bridge
__________-filled vesicles at the axon terminal fuse with pre-synaptic membrane
acetylcholine
synaptic vesicles in the neuromuscular junction contain
acetylcholine
