mam phys ch9
When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands do not diminish in length.
True
cardiac muscle has a limited regenerative capacity.
True
1) What is the role of tropomyosin in skeletal muscles? A) Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules. B) Tropomyosin is the chemical that activates the myosin heads. C) Tropomyosin serves as a contraction inhibitor by blocking the actin binding sites on the myosin molecules. D) Tropomyosin is the receptor for the motor neuron neurotransmitter.
A
12) Rigor mortis occurs because ________. A) no ATP is available to release attached actin and myosin molecules B) proteins are beginning to break down, thus preventing a flow of calcium ions C) the cells are dead D) sodium ions leak into the muscle causing continued contractions
A
21) Which of the following describes the cells of unitary smooth muscle? A) They exhibit spontaneous action potentials. B) They are used for vision and hair raising. C) They depend upon recruitment using the autonomic nervous system. D) They consist of muscle fibers that are structurally independent of each other.
A
22) Which of the following is true about smooth muscle? A) Certain smooth muscle cells can actually divide to increase their numbers. B) Smooth muscle has well-developed T tubules at the site of invagination. C) Smooth muscle, in contrast to skeletal muscle, cannot synthesize or secrete any connective tissue elements. D) Smooth muscle cannot stretch as much as skeletal muscle.
A
23) Smooth muscle is characterized by all of the following except ________. A) there are more thick filaments than thin filaments B) there are no sarcomeres C) it appears to lack troponin D) there are noncontractile intermediate filaments that attach to dense bodies within the cell
A
26) An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________. A) glycolysis B) the electron transport chain C) the citric acid cycle D) hydrolysis
A
34) What part of the sarcolemma contains acetylcholine receptors? A) motor end plate B) part adjacent to another muscle cell C) any part of the sarcolemma D) end of the muscle fiber
A
35) Although all the anatomical parts of muscle work together to give it it's characteristics, which of the following proteins listed below would be most associated with the characteristics of extensibility? A) elastic (titin) filaments B) potassium (K+) leak channels C) acetylcholine receptors in the motor end plate D) thick (myosin) filaments
A
36) Although all the anatomical parts of muscle work together to give it it's characteristics, which of the following proteins listed below would be most associated with the characteristics of excitability? A) acetylcholine receptors in the motor end plate B) the Na+-K+ pump C) actin of thin filaments D) elastic (titin) filaments
A
42) A myosin molecule in the thick filaments can be considered a protein having a quaternary structural level. Which of the following best describes this structural level? A) Myosin molecules consist of two heavy and to light polypeptide chains. B) Myosin has an ATP binding site, actin binding site and flexible hinge region. C) Myosin is a primary component within a myofibril. D) Myosin is involved in the power stroke of muscle contraction.
A
43) Curare is a poisonous plant extract. Curare molecules have a chemical structure like the neurotransmitter ACh. Curare can bind to the ACh receptor site on the chemically gated ion channels in the motor end plate. Even though curare will bind to the receptor site it will not open the ion channel and no ions will pass through. What do you think the symptoms of curare poisoning would look like? A) Curare will only affect muscles with ACh receptors, paralyzing them. B) Smooth muscles will become stimulated causing quick movement of nutrients through the digestive system. C) Curare will only affect cardiac muscle, causing fibrillations of the heart. D) Muscles will respond too quickly and cause a severe tremor.
A
48) Addition of more myoglobin to a muscle fiber would have the largest effect on ________. A) fast oxidative and slow oxidative fibers B) fast glycolytic and fast oxidative fibers C) fast glycolytic fibers only D) fast oxidative fibers only
A
50) Reduction in blood flow to a muscle fiber would have the greatest effect on ________. A) slow oxidative fibers B) fast oxidative fibers C) both slow and fast oxidative D) fast glycolytic
A
53) If given the exact same amount of ATP, which of the three fiber types would be able to contract for the longest amount of time? A) slow oxidative fibers B) fast glycolytic fibers C) both fast glycolytic and fast oxidative fibers D) fast oxidative fibers
A
7) What does excess postexercise oxygen consumption represent? A) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used B) the amount of oxygen equal to the oxygen already used C) the amount of oxygen taken into the body immediately after the exertion D) amount of oxygen needed for aerobic activity to accomplish the same amount of work
A
Match the following: A) A band B) Z discs C) I band D) Myosin Both actin and myosin are found in the ________.
A
Match the following: A) A band B) Z discs C) I band D) Myosin The myosin filaments are located in the ________.
A
Match the following: A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers C) Fast (oxidative or glycolytic), fatigable fibers A relatively high percentage are found in successful marathon runners.
A
Match the following: A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers C) Fast (oxidative or glycolytic), fatigable fibers Abundant in muscles used to maintain posture.
A
Match the following: A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers C) Fast (oxidative or glycolytic), fatigable fibers Depends on oxygen delivery and aerobic mechanisms.
A
Match the following: A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers C) Fast (oxidative or glycolytic), fatigable fibers Red fibers, the smallest of the fiber types.
A
Match the following: A) Sodium ions B) Acetylcholinesterase C) Calcium ions D) Acetylcholine E) Creatine phosphate It diffuses across the cell membrane resulting in depolarization.
A
Match the following: A) Tetanus B) Maximal stimulus C) Wave summation D) Muscle tone E) Multiple motor unit summation Continued sustained smooth contraction due to rapid stimulation.
A
Match the sport to the energy system primarily used to perform the activity: A) Direct phosphorylation B) Anaerobic pathway C) Aerobic pathway Weight lifting.
A
The thin filaments (actin) contain a polypeptide subunit G actin that bears active sites for myosin attachment.
True
29) After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction? A) the tropomyosin blocking the myosin once full contraction is achieved B) acetylcholinesterase destroying the ACh C) calcium ions returning to the terminal cisternae D) the action potential stops going down the overloaded T tubules
B
32) Of the following muscle types, which has only one nucleus, no sarcomeres, and few gap junctions? A) skeletal muscle B) multiunit smooth muscle C) cardiac muscle D) visceral smooth muscle
B
11) Which of the following surrounds the individual muscle cell? A) epimysium B) endomysium C) fascicle D) perimysium
B
14) The contractile units of skeletal muscles are ________. A) microtubules B) myofibrils C) mitochondria D) T tubules
B
16) What is the functional role of the T tubules? A) synthesize ATP to provide energy for muscle contraction B) enhance cellular communication during muscle contraction C) stabilize the G and F actin D) hold cross bridges in place in a resting muscle
B
17) When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods? A) latent period B) refractory period C) fatigue period D) relaxation period
B
18) In an isotonic contraction, the muscle ________. A) never converts pyruvate to lactate B) changes in length and moves the "load" C) does not change in length but increases tension D) rapidly resynthesizes creatine phosphate and ATP
B
19) Which of the following is the correct sequence of events for muscle contractions? A) muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, sliding of myofilaments B) motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments C) neurotransmitter release, motor neuron action potential, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke D) neurotransmitter release, muscle cell action potential, motor neuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke
B
2) Which muscle cells have the greatest ability to regenerate? A) no muscle can regenerate B) smooth C) skeletal D) cardiac
B
20) The mechanism of contraction in smooth muscle is different from skeletal muscle in that ________. A) ATP energizes the sliding process B) the site of calcium regulation differs C) the trigger for contraction is a rise in intracellular calcium D) actin and myosin interact by the sliding filament mechanism
B
25) Which of the following statements is true? A) Cardiac muscle cells have many nuclei. B) Striated muscle cells are long and cylindrical with many nuclei. C) Smooth muscle cells have T tubules. D) Cardiac muscle cells are found in the heart and large blood vessels.
B
27) Muscle tone is ________. A) the condition of athletes after intensive training B) a state of sustained partial contraction C) the ability of a muscle to efficiently cause skeletal movements D) the feeling of well-being following exercise
B
37) Although all the anatomical parts of muscle work together to give it it's characteristics, which of the following proteins listed below would be most associated with the characteristics of contractility? A) voltage gated sodium channels B) thick (myosin) filaments C) elastic (titin) filaments D) potassium (K+) leak channels
B
44) Myasthenia gravis is a disease that is believed to be caused by autoimmune disorder, resulting in the loss of ACh receptors at the motor end plate of muscle fibers. Which of the following is likely to be a symptom of myasthenia gravis? A) dehydration with headache B) weakness of muscle C) seizures and uncontrollable muscle movement D) coma and loss of voluntary muscle movement
B
46) If a muscle fiber were to suddenly and permanently stop producing ATP the fiber would no longer be able to actively transport calcium out of the cytoplasm (sarcoplasm) and the intracellular calcium concentration would rise. Which of the following would you expect to happen? A) The fiber would twitch uncontrollably due to excessive calcium bound to troponin. B) Myosin would be able to bind to the exposed binding sites on thin filaments but it would not be able to detach. C) Calcium would be transported to the sarcoplasmic reticulum therefore contractions would cease. D) No change would occur in a muscle that was relaxed to begin with.
B
47) When a sarcomere contracts and thin filaments move over thick filaments you would expect to see ________. A) the H zone to appear wider B) the I bands to appear smaller C) the I bands to appear wider D) the A band to appear darker
B
52) Addition of more mitochondria to a muscle fiber will have the least effect on ________. A) slow oxidative fibers B) fast glycolytic fibers C) fast oxidative fibers D) both slow and fast oxidative fibers
B
6) What structure in skeletal muscle cells functions in calcium storage? A) intermediate filament network B) sarcoplasmic reticulum C) mitochondria D) myofibrillar network
B
Match the following: A) A band B) Z discs C) I band D) Myosin A sarcomere is the distance between two ________.
B
Match the following: A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers C) Fast (oxidative or glycolytic), fatigable fibers Have very fast-acting myosin ATPases and depend upon anaerobic metabolism during contraction.
B
Match the following: A) Sodium ions B) Acetylcholinesterase C) Calcium ions D) Acetylcholine E) Creatine phosphate Breaks down ACh into its building blocks, rendering it ineffective.
B
Match the following: A) Tetanus B) Maximal stimulus C) Wave summation D) Muscle tone E) Multiple motor unit summation The stimulus above which no stronger contraction can be elicited, because all motor units are firing in the muscle.
B
Match the sport to the energy system primarily used to perform the activity: A) Direct phosphorylation B) Anaerobic pathway C) Aerobic pathway 25 meter swim.
B
15) What is the functional unit of a skeletal muscle called? A) a myofibril B) the sarcoplasmic reticulum C) a sarcomere D) a myofilament
C
28) The sliding filament model of contraction involves ________. A) actin and myosin lengthening in order to slide past each other B) the Z discs sliding over the myofilaments C) actin and myosin sliding past each other and partially overlapping D) the shortening of thick filaments so that thin filaments slide past
C
30) Which of the following statements is most accurate? A) T tubules may be sliding during isotonic contraction. B) Myofilaments slide during isometric contractions. C) Muscle tension remains relatively constant during isotonic contraction. D) The I band lengthens during isotonic contraction.
C
31) What is the most distinguishing characteristic of muscle tissue? A) it is composed of multiple cells working together B) the ability to respond to nervous stimulation C) the ability to transform chemical energy into mechanical energy to move the body D) its cells' in ability to reproduce by mitosis
C
33) Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped, ________. A) maximum force production would result because the muscle has a maximum range of travel B) ATP consumption would increase because the sarcomere is "trying" to contract C) no muscle tension could be generated D) cross bridge attachment would be optimum because of all the free binding sites on actin
C
38) Oxygen starved tissues can release chemical signals into the blood that can change the diameter of nearby blood vessels delivering oxygen and nutrients to the tissues. In doing so the blood vessels will respond through vasodilation (widening of the vessel). Which muscle type is responsible for this vasodilation? A) skeletal muscle B) striated muscle C) smooth muscle D) cardiac muscle
C
39) Of the following items listed below, which is the best description for why skeletal muscle stores glycogen. A) Glycogen provides a smooth surface for filaments to slide on. B) Glycogen is part of muscles rigid supporting framework. C) Skeletal muscle is a heavy consumer of energy. D) The glycogen is an insulating layer that helps regulate body temperature.
C
40) During development embryonic cells will fuse to form muscle fibers. This will result in ________. A) the coordination of nerve signals to muscle fibers B) the striations that appear in skeletal and cardiac muscle tissues C) multinucleated muscle fibers that can extend as long as 30 centimeters D) interlocking of cells that can prevent the filaments from sliding
C
41) Approximately 80% of a muscle fiber's volume are the myofibrils. This characteristic reflects muscles ability to ________. A) store oxygen molecules that can be used in aerobic respiration B) produce relatively high amounts of ATP C) produce movement through contractile force D) generate and propagate action potential
C
45) Which of the following statements best illustrates the fact that skeletal muscle is voluntary muscle? A) Skeletal muscle is wrapped in several layers of connective tissue. The deepest layer being the endomysium. B) Skeletal muscle appears striated due to the structure of the sarcomeres. C) Skeletal muscle fibers are innervated by somatic motor neurons. D) The shivering reflex aids in maintaining body temperature.
C
54) The 100 meter dash is a quick and short run requiring explosive speed. On completion of the dash the runners will continue to breathe hard for several seconds to minutes even though they are no longer running. Which of the following is the best explanation for why this is so? A) Since the exercise was mostly aerobic exercise, the runners' bodies have not yet realized the run is over. B) The runners' fast oxidative muscles are so slow to utilize oxygen it only begins aerobic respiration by the time the run has finished. C) The runners' use of stored oxygen, glucose and creatine phosphate is being replenished and this requires a prolonged increase of oxygen intake. D) Slow oxidative fibers are recruited last and have only started to work at completion of the run.
C
8) Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the neurotransmitter is released by exocytosis, diffuses across the synaptic cleft, and binds to its receptors. A) relaxation B) refractory C) latent D) contraction
C
9) Creatine phosphate functions in the muscle cell by ________. A) forming a temporary chemical compound with myosin B) forming a chemical compound with actin C) storing energy that will be transferred to ADP to resynthesize ATP D) inducing a conformational change in the myofilaments
C
Match the following: A) A band B) Z discs C) I band D) Myosin The ________ contains only the actin filaments.
C
Match the following: A) Slow (oxidative), fatigue-resistant fibers B) Fast (oxidative or glycolytic), fatigable fibers C) Fast (oxidative or glycolytic), fatigable fibers Contain abundant amounts of glycogen.
C
Match the following: A) Sodium ions B) Acetylcholinesterase C) Calcium ions D) Acetylcholine E) Creatine phosphate Activates synaptic vesicles in axon terminals to fuse with plasma membrane of axon terminal.
C
Match the following: A) Sodium ions B) Acetylcholinesterase C) Calcium ions D) Acetylcholine E) Creatine phosphate The final chemical messenger and "trigger" for muscle contraction. It binds to troponin.
C
Match the following: A) Tetanus B) Maximal stimulus C) Wave summation D) Muscle tone E) Multiple motor unit summation The situation in which contractions become stronger due to stimulation before complete relaxation occurs.
C
Match the sport to the energy system primarily used to perform the activity: A) Direct phosphorylation B) Anaerobic pathway C) Aerobic pathway Marathons.
C
10) What is the primary function of wave summation? A) increase muscle tension B) prevent muscle relaxation C) prevent muscle fatigue D) produce smooth, continuous muscle contraction
D
13) The oxygen-binding protein found in muscle cells is ________. A) hemoglobin B) immunoglobin C) ATP D) myoglobin
D
24) Muscle tissue has all of the following properties except ________. A) excitability B) extensibility C) contractility D) secretion
D
3) Which of the following would be recruited later in muscle stimulation when contractile strength increases? A) large motor units with small, highly excitable neurons B) motor units with the longest muscle fibers C) many small motor units with the ability to stimulate other motor units D) motor units with larger, less excitable neurons
D
4) Which of the following is a factor that affects the velocity and duration of muscle contraction? A) number of muscle fibers stimulated B) muscle length C) size of the muscle fibers stimulated D) load on the fiber
D
49) Exhaustion of glycogen storage within a muscle fiber would have the biggest effect on ________. A) both slow and fast oxidative fibers B) slow oxidative fibers C) fast oxidative fibers D) fast glycolytic fibers
D
5) Myoglobin ________. A) breaks down glycogen B) is a protein involved in the direct phosphorylation of ADP C) produces the end plate potential D) stores oxygen in muscle cells
D
51) A potential benefit of recruiting slow oxidative fibers for contraction before recruiting fast oxidative and fast glycolytic fibers might be ________. A) because they are slower to respond, slow oxidative fibers must be stimulated first in order to contract simultaneously with the faster fibers B) there is little to no benefit from recruiting slow oxidative fibers first and therefore it is in fact fast glycolytic fibers that will be recruited first C) recruiting slow oxidative fibers early helps to tire them out first so that they won't interfere with the more powerful contractions of fast glycolytic fibers D) this will help to allow for fine control with delicate contractile force with a small stimulus
D
Match the following: A) A band B) Z discs C) I band D) Myosin The thicker filaments are the ________ filaments.
D
Match the following: A) Sodium ions B) Acetylcholinesterase C) Calcium ions D) Acetylcholine E) Creatine phosphate A neurotransmitter released at motor end plates by the axon terminals.
D
Match the following: A) Tetanus B) Maximal stimulus C) Wave summation D) Muscle tone E) Multiple motor unit summation Determined by alternating motor units of a muscle organ even when the muscle is at rest.
D
Match the following: A) Sodium ions B) Acetylcholinesterase C) Calcium ions D) Acetylcholine E) Creatine phosphate Used to convert ADP to ATP by transfer of a high-energy phosphate group. A reserve high-energy compound.
E
Match the following: A) Tetanus B) Maximal stimulus C) Wave summation D) Muscle tone E) Multiple motor unit summation How a smooth increase in muscle force is produced.
E
A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate.
False
During isometric contraction, the energy used appears as movement.
False
Muscle contraction will always promote movement of body parts regardless of how they are attached.
False
Once a motor neuron has fired, all the muscle fibers in a muscle contract.
False
The force of muscle contraction is controlled by multiple motor unit summation or recruitment.
True
A contraction in which the muscle does not shorten but its tension increases is called isometric contraction.
True
A resting potential is caused by a difference in the concentration of certain ions inside and outside the cell.
True
Although there are no sarcomeres, smooth muscle still possesses thick and thin filaments.
True
An increase in the calcium ion level in the sarcoplasm starts the sliding of the thin filaments. When the level of calcium ions declines, sliding stops.
True
Cells of unitary smooth muscle are found in the longitudinal and circular muscle layers of the intestine.
True
Eccentric contractions are more forceful than concentric contractions.
True
Muscle cells store more creatine phosphate than ATP resulting in the muscle having a reserve source of energy.
True
Muscle tone is the small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units.
True
One of the functions of skeletal muscle contraction is production of heat.
True
Peristalsis is characteristic of smooth muscle.
True
Smooth muscles relax when intracellular Ca2+ levels drop but may not cease contractions.
True
The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily.
True
1) Only ________ muscle cells are multinucleated.
skeletal