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Physiology Chapter 12
Mechanism of Contraction and Neural Control
47
Physiology
Undergraduate 4
03/18/2014

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Term
Muscles which move a limb away the midline of the body are termed
A. abductor muscles.
B. adductor muscles.
C. extensor muscles.
D. flexor muscles
Definition
A. abductor muscles.
Term
A muscle that constricts an opening is a/an
A. extensor.
B. levator.
C. antagonist.
D. sphincter.
Definition
D. sphincter.
Term
. The prime mover of any skeletal movement is called the
A. flexor.
B. agonist.
C. abductor.
D. antagonist.
Definition
B. agonist.
Term
. Each fascicle of a muscle is surrounded by the
A. perimysium.
B. epimysium.
C. endomysium.
Definition
A. perimysium.
Term
The light band of a skeletal muscle is known as the
A. A band.
B. Z disc.
C. I band.
D. H zone.
Definition
C. I band.
Term
Duchenne's muscular dystrophy
A. is an X-linked recessive trait.
B. most often affects women.
C. involves degeneration of the smooth muscle dense bodies.
D. All of the choices are correct.
Definition
A. is an X-linked recessive trait.
Term
Somatic motor neurons release the neurotransmitter _________ at the neuromuscular junction.
A. dopamine
B. acetylcholine
C. norepinephrine
D. serotonin
Definition
B. acetylcholine
Term
. Each somatic motor neuron with all the muscle fibers it innervates is a
A. fascicle.
B. varicosity.
C. motor unit.
D. sarcolemma
Definition
C. motor unit.
Term
. Subunits of skeletal muscle cells that are composed of sarcomeres are called
A. myofibrils.
B. myofilaments.
C. sarcolemmas.
D. transverse tubules
Definition
A. myofibrils.
Term
. What structure is composed of protein filaments and is located in the center of the thick filaments?
A. Z disk
B. titin
C. M line
D. actin
Definition
C. M line
Term
What structure runs the length of the sarcomere through the thick filaments and contributes to the elastic recoil in muscle?
A. Z disk
B. titin
C. M line
D. actin
Definition
B. titin
Term
What structure runs from Z line to Z line?
A. A band
B. I band
C. sarcomere
D. myofibril
Definition
C. sarcomere
Term
Myosin contains binding sites for ______________ and ______________.
A. sodium, calcium.
B. troponin, ATP.
C. ATP, actin.
D. actin, calcium.
Definition
C. ATP, actin.
Term
. During skeletal muscle contraction, adjacent _________ are pulled closer together as the _______ between them shorten.
A. A bands; I bands
B. I bands; A bands
C. Z disks; A bands
D. Z disks; I bands
Definition
A. A bands; I bands
Term
During skeletal muscle contraction,
A. the H zone increases in size.
B. Ca2+ associates with tropomyosin.
C. myosin heads interact with tropomyosin.
D. thin filaments slide across thick filaments.
Definition
D. thin filaments slide across thick filaments.
Term
Which of the following does NOT occur during the cross bridge cycle?
A. a second ATP binding causes cross bridges to form.
B. ADP is released at the end of the power stroke.
C. energized myosin heads bind troponin.
Definition
C. energized myosin heads bind troponin.
Term
The _________ complex contains three proteins designated as the I, T, and C types.
A. actin
B. myosin
C. tropomyosin
D. troponin
Definition
D. troponin
Term
. The movement of the troponin-tropomyosin complex requires
A. ATP.
B. Ca2+.
C. Acetylcholine.
D. Na+.
Definition
B. Ca2+.
Term
The Ca2+ required for skeletal muscle contraction
A. is released from the sarcoplasmic reticulum.
B. enters the cell due to the opening of voltage regulated Ca2+ channels from the T tubules.
C. is actively transported into the cell.
D. is released from mitochondria.
Definition
A. is released from the sarcoplasmic reticulum.
Term
The pumps that actively transport calcium back into the _______ are called Ca2+ -ATPase pumps.
A. transverse tubules
B. sarcoplasmic reticulum
C. neuromuscular junction
D. None of the choices are correct.
Definition
B. sarcoplasmic reticulum
Term
. Which of the following is NOT true of the relaxation of a muscle fiber?
A. ATP is needed to fuel the calcium pumps
B. calcium release channels close
C. the action potential must continue
D. Ca2+ moves from the sarcoplasm to the sarcoplasmic reticula
Definition
C. the action potential must continue
Term
The inability of muscle cells to relax due to high frequency stimulation is termed
A. treppe.
B. recruitment.
C. twitch.
D. tetanus.
Definition
D. tetanus.
Term
. _______ refer to muscle contractions that produce a shortening muscle with a constant contraction strength at a given load.
A. Treppe contractions
B. Isotonic contractions
C. Twitch contractions
D. Isometric contractions
Definition
B. Isotonic contractions
Term
Which of the following statements about muscles is FALSE?
A. During isometric contractions muscles do not generate tension.
B. The strength of contraction is directly proportional to the stimulus intensity.
C. Tendons act as part of the series-elastic component of a muscle.
D. During muscle contraction the Z disks move closer together.
Definition
A. During isometric contractions muscles do not generate tension.
Term
. A muscle contraction against a resistance that is greater than the force and causes muscle lengthening is a(n)
A. concentric contraction.
B. isometric contraction.
C. eccentric contraction.
D. isokinetic contraction.
Definition
C. eccentric contraction.
Term
.. A shortening of the muscle that occurs when the tension is greater than the load is a(n)
A. concentric contraction.
B. isometric contraction.
C. eccentric contraction.
D. isokinetic contraction.
Definition
A. concentric contraction.
Term
Which of the following is NOT true about the series-elastic component to contraction?
A. It absorbs some of the tension of muscle contraction.
B. It provides for elastic recoil when muscles relax.
C. It must loosen for a muscle to shorten.
D. It is provided by tendons.
Definition
C. It must loosen for a muscle to shorten.
Term
. Which of the following does NOT increase the strength of the muscle contraction?
A. a high number of fibers stimulated
B. increased frequency of stimulation
C. thicker muscle fiber
D. resting sarcomere length of 3.6µm
Definition
Term
. In regards to the relationship between resting muscle fiber length and tension generated
A. maximal tension is generated when the thick and thin filaments slightly overlap.
B. maximal tension is generated when the thick and thin filaments do not overlap.
C. maximal tension is generated when the thick and thin filaments greatly overlap.
D. the amount of overlap is unimportant in determining maximal tension
Definition
A. maximal tension is generated when the thick and thin filaments slightly overlap.
Term
. Skeletal muscles at rest obtain most of their energy from the aerobic respiration of
A. glucose.
B. protein.
C. fatty acids.
D. glycogen.
Definition
C. fatty acids.
Term
ATP in muscle contraction is needed for
A. attachment of myosin cross bridges to actin.
B. release of myosin cross bridges from actin.
C. pumping of Ca2+ back into the sarcoplasmic reticulum.
D. All of the choices are correct.
Definition
D. All of the choices are correct.
Term
Which of the following is true under heavy exercise in for the first 30 minutes of activity heavy exercise?
A. Most energy is derived from glycogen and plasma glucose.
B. The percentage of energy obtained from plasma free fatty acids exceeds that of mild exercise.
C. The percentage of energy obtain from plasma glucose is less than that of moderate exercise.
D. All of the choices are correct.
Definition
A. Most energy is derived from glycogen and plasma glucose.
Term
Fatty acids provide the majority of the energy for muscle metabolism when a person is
A. exercising at 25% of VO2max.
B. exercising at 50% of VO2max.
C. exercising at 75% of VO2max.
D. exercising at 100% of VO2max.
Definition
A. exercising at 25% of VO2max.
Term
. The first 1 to 2 minutes of moderate to heavy exercise relies on _____ for ATP production.
A. aerobic respiration of glucose
B. anaerobic respiration of glucose
C. aerobic respiration of fatty acids
D. anaerobic respiration of amino acids
Definition
B. anaerobic respiration of glucose
Term
. Repaying the oxygen debt requires replacing oxygen that was
A. bound to blood hemoglobin.
B. bound to muscle myoglobin.
C. used for tissue warm up.
D. All of the choices are correct.
Definition
D. All of the choices are correct.
Term
. A reserve of high energy phosphate is stored in muscle as
A. phosphocreatine.
B. adenosine triphosphate.
C. glucose 6-phosphate.
D. creatine kinase.
Definition
A. phosphocreatine.
Term
Slow twitch fibers have a ______ oxidative capacity and ________ glycogen content.
A. high, high
B. high, low
C. low, low
D. low, high
Definition
B. high, low
Term
Type I skeletal muscle fibers
A. contract rapidly.
B. have a large diameter.
C. have a low myoglobin concentration.
D. have numerous mitochondria.
Definition
D. have numerous mitochondria.
Term
. Central fatigue is caused by
A. decreased H+ concentration in the muscle cells.
B. increased glycogen in muscle cells.
C. changes in the CNS.
D. All of the choices are correct.
Definition
C. changes in the CNS.
Term
Which of the following is NOT a contributing factor to skeletal muscle fatigue?
A. increased intracellular K+
B. depletion of intracellular K+
C. accumulation of extracellular K+
D. accumulation of cytoplasmic Pi
Definition
A. increased intracellular K+
Term
The amount of fat stored in skeletal muscles will be ______________ by endurance training.
A. increased
B. decreased
C. unchanged
Definition
A. increased
Term
Endurance training results in increased
A. muscle mitochondria number.
B. glycogen depletion during exercise.
C. number of type IIB fibers.
D. lactate production per unit tim
Definition
A. muscle mitochondria number.
Term
The greater the level of physical training, the higher the proportion of energy derived from the oxidation of ____ during exercise below VO2max.
A. glucose
B. protein
C. amino acids
D. fatty acids
Definition
D. fatty acids
Term
Muscle hypertrophy is due to
A. increased number of myofibrils in the muscle fiber.
B. increased number of muscle fibers.
C. increased size of the myofibrils.
D. Both increased number of myofibrils in the muscle fiber and increased size of the myofibrils are correct.
Definition
D. Both increased number of myofibrils in the muscle fiber and increased size of the myofibrils are correct.
Term
. Myostatin is
A. a paracrine regulator that inhibits muscle growth.
B. a paracrine regulator that stimulates muscle growth.
C. an autocrine regulator that inhibits muscle growth.
D. an autocrine regulator that stimulates muscle growth
Definition
A. a paracrine regulator that inhibits muscle growth
Term
Muscle repair is due to ____ forming myotubes that fuse to form new muscle fibers.
A. satellite cells
B. myofibrils
C. muscle cells
D. All of the choices are correct.
Definition
A. satellite cells
Term
. Degeneration of ______________ motor neurons occurs in amyotrophic lateral sclerosis.
A. upper
B. middle
C. lower
D. both middle and lower
Definition
C. lower
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