Deck 12: Muscle

Question 1

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.

Answer 1

A

Question 2

The origin is the point of muscle attachment that is most stationary.

Answer 2

True

Question 3

Each fascicle of a muscle is surrounded by the

A)perimysium.
B)epimysium.
C)endomysium.
D)sarcolemma.

Answer 3

A

Question 4

The light band of a skeletal muscle is known as the

A)A band.
B)Z disc.
C)I band.
D)H zone.

Question 5

Z lines are found bisecting the A bands.

Question 6

Skeletal muscles with a low innervation ratio have a low degree of neural control.

Question 7

Sarcomeres contain elastic titin filaments which help the muscles return to their resting length during muscle relaxation.

Question 8

When skeletal muscle cells contract, they increase in length.

Question 9

A muscle that constricts an opening is a/an

A)extensor.
B)levator.
C)antagonist.
D)sphincter.

Question 10

Thin filaments are composed of myosin and tropomyosin.

Question 11

The epimysium surrounds the individual muscle cells.

Question 12

Motor unit recruitment allows for _________ contraction strength.

A)increased
B)decreased
C)no change in

Question 13

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

Question 14

Somatic motor neurons release the neurotransmitter _________ at the neuromuscular junction.

A)dopamine
B)acetylcholine
C)norepinephrine
D)serotonin

Question 15

Subunits of skeletal muscle cells that are composed of sarcomeres are called

A)myofibrils.
B)myofilaments.
C)sarcolemmas.
D)transverse tubules.

Question 16

The deadly botulinum toxin can be used in the cosmetic treatment of skin wrinkles.

Question 17

Flexors increase the angle at a joint.

Question 18

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.

Question 19

Each somatic motor neuron with all the muscle fibers it innervates is a

A)fascicle.
B)varicosity.
C)motor unit.
D)sarcolemma.

Question 20

The prime mover of any skeletal movement is called the

A)flexor.
B)agonist.
C)abductor.
D)antagonist.

Question 21

During skeletal muscle contraction the A band decreases in size.

Question 22

What structure runs from Z line to Z line?

A)A band
B)I band
C)sarcomere
D)myofibril

Question 23

The thick filament is split by a Z disc.

Question 24

________ is characterized by continued attachment of myosin heads to actin filaments due to a lack of ATP.

A)Tetanus
B)Rigor mortis
C)Flaccid paralysis
D)Treppe

Question 25

The actin filament is a polymer formed from 300 to 400 globular subunits called

A)I-actin.
B)T-actin.
C)G-actin.
D)C-actin.

Question 26

Myosin will not bind to actin unless ADP is bound to the myosin head.

Question 27

Crossbridge formation occurs when myosin heads attach to actin molecules located on the thin filaments.

Question 28

The _________ complex contains three proteins designated as the I, T, and C types.

A)actin
B)myosin
C)tropomyosin
D)troponin

Question 29

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

Question 30

The thick filament is also called the

A)A band.
B)I band.
C)H zone
D)M line

Question 31

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.
D)ATP hydrolysis allows for cross bridge formation.

Question 32

The movement of the troponin-tropomyosin complex requires

A)ATP.
B)Ca²⁺.
C)Acetylcholine.
D)Na⁺.

Question 33

Ca²⁺ must bind to tropomyosin so that the myosin binding sites on actin will be accessible to the myosin.

Question 34

Transverse tubules contain voltage-gated calcium channels that respond to membrane depolarization and are directly coupled to the calcium release channels in the sarcoplasmic reticulum.

Question 35

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

Question 36

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.

Question 37

Myosin contains binding sites for ______________ and ______________.

A)sodium, calcium.
B)troponin, ATP.
C)ATP, actin.
D)actin, calcium.

Question 38

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

Question 39

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.

Question 40

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.

Question 41

Isotonic muscle contractions are often preceded by isometric contractions.

Question 42

A force-velocity curve shows the _______ relationship between the force opposing muscle contraction and the velocity of muscle shortening.

A)direct
B)inverse
C)increased
D)no

Question 43

High-energy phosphates are stored in skeletal muscle as glycogen ATP.

Question 44

The staircase effect or _____ represents a warm up effect due to increasing intracellular calcium concentrations.

A)treppe
B)tetanus
C)incomplete tetanus
D)tonus

Question 45

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.

Question 46

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

Question 47

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.

Question 48

Skeletal muscles at rest obtain most of their energy from the aerobic respiration of

A)glucose.
B)protein.
C)fatty acids.
D)glycogen.

Question 49

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.

Question 50

_______ 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

Question 51

Exceeding the VO_2max will result in lactate production by the muscle.

Question 52

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.

Question 53

When a muscle cell generates tension but does not shorten, a(n) ______ contraction occurs.

A)isometric
B)isotonic
C)spastic
D)flaccid

Question 54

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.

Question 55

Increasing the frequency of action potentials in a somatic motor neuron will induce increased force of muscle contraction.

Question 56

Summation occurs in muscle cells when action potentials are added to produce a greater force stimulating contraction.

Question 57

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.

Question 58

Insertion of ______________ in the muscle cell membrane increases cellular glucose uptake.

A)GLUT1
B)GLUT2
C)GLUT3
D)GLUT4

Question 59

The inability of muscle cells to relax due to high frequency stimulation is termed

A)treppe.
B)recruitment.
C)twitch.
D)tetanus.

Question 60

Smooth, sustained muscle contractions in vivo are due to synchronous activation of motor units.

Question 61

Muscle fatigue

A)occurs when muscles are only partially able to contract.
B)occurs when muscle cell pH decreases.
C)occurs when muscle cell pH increases.
D)occurs due to decreased extracellular K⁺.

Question 62

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

Question 63

Fatigue appears to occur due to the reduced ability of the sarcoplasmic reticulum release of Ca²⁺ with neural stimulation.

Question 64

Blood lactate will begin to rise when exercise is performed at a rate that is

A)15% of VO_2max.
B)25% of VO_2max.
C)50% of VO_2max.
D)85% of VO_2max.

Question 65

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.

Question 66

Endurance training increases the oxidative capacity of a muscle cell.

Question 67

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

Question 68

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 time.

Question 69

The fastest shortening muscle fiber in humans is the

A)type IIA.
B)type IIB.
C)type IIX.
D)type I.

Question 70

Type I skeletal muscle fibers

A)contract rapidly.
B)have a large diameter.
C)have a low myoglobin concentration.
D)have numerous mitochondria.

Question 71

A reserve of high energy phosphate is stored in muscle as

A)phosphocreatine.
B)adenosine triphosphate.
C)glucose 6-phosphate.
D)creatine kinase.

Question 72

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.

Question 73

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.

Question 74

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.

Question 75

Fatty acids provide the majority of the energy for muscle metabolism when a person is

A)exercising at 25% of VO_2max.
B)exercising at 50% of VO_2max.
C)exercising at 75% of VO_2max.
D)exercising at 100% of VO_2max.

Question 76

Slow twitch fibers have a ______ oxidative capacity and ________ glycogen content.

A)high, high
B)high, low
C)low, low
D)low, high

Question 77

The greater the level of physical training, the higher the proportion of energy derived from the oxidation of ____ during exercise below VO_2max.

A)glucose
B)protein
C)amino acids
D)fatty acids

Question 78

Fast twitch fibers have the greatest resistance to fatigue.

Question 79

Type IIBX skeletal muscle fibers

A)generate less tension than type IIA fibers.
B)fatigue very slowly.
C)generate more tension than type I fibers.
D)have a high myoglobin concentration.

Question 80

The amount of fat stored in skeletal muscles will be ______________ by endurance training.

A)increased
B)decreased
C)unchanged