Deck 10: Muscle Tissue Physiology

Question 1

The plasma membrane of a muscle cell is known as the:

A) myofibril.
B) sarcolemma.
C) sarcoplasmic reticulum.
D) sarcomere.

Answer 1

B

Question 2

What do skeletal muscle tissue and cardiac muscle tissue share in common?

A) Both skeletal and cardiac muscle tissues perform peristalsis.
B) Both skeletal and cardiac muscle tissues possess intercalated discs.
C) Both skeletal and cardiac muscle tissues are striated.
D) Both skeletal and cardiac muscle tissues are voluntary.

Answer 2

C

Question 3

What part of the myofibril shortens to produce contractions of the muscle fiber?

A) myosin filaments
B) A band
C) sarcomere
D) elastic filaments

Answer 3

C

Question 4

The storage and release of calcium ions is the key function of the:

A) sarcoplasm.
B) sarcoplasmic reticulum.
C) mitochondrion.
D) sarcolemma.

Question 5

Which protein does NOT belong in a thin filament?

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

Question 6

What is the functional contractile unit of the myofibril?

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

Question 7

When a skeletal muscle fiber contracts:

A) Z discs move farther apart while the A bands shorten.
B) the H zone and I bands narrow.
C) the A bands shorten while the I bands lengthen.
D) the H zone narrows while the I bands widen.

Question 8

What characteristic is NOT descriptive of cardiac muscle tissue?

A) striations
B) voluntary muscle contractions
C) located in the heart
D) intercalated discs

Question 9

The degree to which a muscle cell can stretch depends on its:

A) extensibility.
B) excitability.
C) contractility.
D) conductivity.

Question 10

A triad consists of:

A) actin filaments, troponin, and tropomyosin.
B) myosin filaments, myosin heads, and myosin tails.
C) a transverse tubule (T ^-tubule) and two terminal cisternae.
D) a fascicle of skeletal muscle cells and its surrounding perimysium.

Question 11

Where should most of the potassium ions be located when a muscle cell is at rest?

A) extracellular fluid
B) sarcoplasmic reticulum
C) tranverse tubules (T ^-tubules)
D) cytosol of the muscle cell

Question 12

The Na⁺/K⁺ pump helps a muscle cell maintain a state of:

A) propagation.
B) resting membrane potential.
C) depolarization.
D) action potential.

Question 13

What anchors thin and elastic filaments in place within the myofibril?

A) M line
B) I band
C) Z disc
D) A band

Question 14

Deep inward extensions of the sarcolemma form a tunnel ^-like network inside the muscle cell known as:

A) myofibrils.
B) the sarcoplasmic reticulum.
C) myofilaments.
D) transverse tubules (T ^-tubules).

Question 15

What is the basic function of all muscle tissue?

A) produce voluntary contractions
B) regulate body temperature
C) generate muscle tension
D) stabilize joints

Question 16

The central region of the A band that lacks thin filaments is the:

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

Question 17

A muscle cell experiencing resting membrane potential is:

A) propagating an action potential.
B) more negatively charged on its exterior than in its interior.
C) experiencing depolarization.
D) polarized.

Question 18

A group of skeletal muscle fibers together with the surrounding perimysium form a(n):

A) endomysium.
B) fascicle.
C) myofibril.
D) ligament.

Question 19

Which of the following statements is the most accurate description of the sliding filament mechanism?

A) thick filaments shorten while thin filaments remain unchanged
B) Z discs slide over the thick and thin filaments
C) both thick and thin filaments shorten
D) thin filaments slide past thick filaments towards the M line.

Question 20

Which of the following wraps and surrounds an individual skeletal muscle fiber?

A) epimysium
B) perimysium
C) sarcoplasmic reticulum
D) endomysium

Question 21

During muscle contraction, myosin crossbridges bind to active sites on:

A) troponin.
B) T ^-tubules.
C) actin.
D) tropomyosin.

Question 22

What value best represents resting membrane potential of skeletal muscle cells?

A) ^-85 mV
B) ⁺15 mV
C) ⁺35 mV
D) 0 mV

Question 23

The binding of a myosin head to an actin molecule is termed a:

A) crossbridge.
B) triad.
C) synaptic cleft.
D) power stroke.

Question 24

What does the depolarization of the transverse tubules (T ^-tubules) promote?

A) release of acetylcholine from vesicles in the motor neuron into the synaptic cleft
B) binding of acetylcholine to ligand ^-gated sodium ion channels
C) entry of sodium ions into the muscle fiber through voltage ^-gated sodium ion channels
D) release of calcium from the sarcoplasmic reticulum

Question 25

What is accomplished by the power stroke?

A) The power stroke allows the myosin heads to bind to actin.
B) The power stroke causes the myosin and actin filaments to shorten and contract.
C) The power stroke results in myosin heads pulling actin toward the center of the sarcomere.
D) The power stroke cocks the myosin head into its high ^-energy position.

Question 26

The synapse of a motor neuron with a muscle fiber is known as the:

A) synaptic bulb.
B) neuromuscular junction.
C) motor end plate.
D) synaptic cleft.

Question 27

A pathway of ATP production that results in the formation of lactic acid is:

A) oxidative catabolism.
B) glycolytic catabolism.
C) anabolism.
D) aerobic catabolism.

Question 28

What happens when troponin and tropomyosin block the active sites of actin?

A) The muscle produces a weak contraction.
B) The muscle relaxes.
C) The muscle contraction reaches peak tension.
D) The muscle contraction increases tension.

Question 29

When an action potential arrives in an axon terminal, synaptic vesicles containing acetylcholine are released by:

A) facilitated diffusion.
B) osmosis.
C) endocytosis.
D) exocytosis.

Question 30

Place the following events of excitation in the correct order. 1) ion channels on the sarcolemma open and sodium ions enter the muscle fiber
2) the entry of sodium ions into the muscle fiber depolarizes the sarcolemma locally
3) acetylcholine is released from vesicles in the motor neuron into the synaptic cleft
4) an action potential arrives at the axon terminal of a motor neuron
5) acetylcholine binds to ligand ^-gated sodium ion channels in the motor end plate

A) 4, 5, 3, 2, 1
B) 2, 4, 3, 5, 1
C) 3, 4, 5, 1, 2
D) 4, 3, 5, 1, 2

Question 31

What are possible products of glycolytic, or anaerobic, catabolism?

A) glucose only
B) ATP, pyruvate, and lactic acid
C) creatine phosphate only
D) oxygen only

Question 32

What is a necessary reactant for glycolytic, or anaerobic, catabolism to proceed?

A) myoglobin
B) creatine phosphate
C) oxygen
D) glucose

Question 33

Which statement best describes the function of myoglobin?

A) Myoglobin stores oxygen in muscle cells.
B) Myoglobin catabolizes glycogen.
C) Myoglobin hydrolyzes ATP.
D) Myoglobin is a source of ATP for muscles.

Question 34

Between the start of the latent period and the start of the contraction period, there is a time interval during which the muscle cannot respond to another stimulus. This brief period is known as the:

A) refractory period.
B) tension period.
C) relaxation period.
D) action potential.

Question 35

The main immediate source of ATP (lasting about 10 seconds) as muscle contractions begin comes from:

A) glucose.
B) creatine phosphate.
C) fat.
D) glycogen.

Question 36

Through which ATP ^-generating mechanism can long ^-lasting muscle contractions be sustained?

A) creatine phosphate reaction
B) anaerobic catabolism
C) glycolysis
D) oxidative catabolism

Question 37

Where are receptors for acetylcholine located?

A) triad
B) axon terminal
C) motor end plate
D) sarcomere

Question 38

Which of the following promotes the depolarization stage?

A) opening of voltage ^-gated potassium ion channels and potassium ions exit the cell
B) closure of voltage ^-gated sodium ion channels
C) hydrolysis of ATP
D) opening of voltage ^-gated sodium ion channels and sodium ions enter the cell

Question 39

During excitation ^-contraction coupling, calcium ion concentration is highest in the:

A) terminal cisterna.
B) sarcolemma.
C) sarcoplasmic reticulum.
D) cytosol of the muscle fiber.

Question 40

What is required for excitation ^-contraction coupling?

A) calcium ions only
B) calcium ions and ATP
C) ATP only
D) neither calcium ions nor ATP

Question 41

The fastest muscle contraction would be produced by a:

A) type IIc fiber.
B) type IIb fiber.
C) type IIx fiber.
D) type I fiber.

Question 42

Smooth muscle and skeletal muscle both possess:

A) myosin and actin filaments.
B) transverse tubules (T ^-tubules).
C) troponin.
D) motor end plates.

Question 43

Provide two characteristics that distinguish skeletal muscle tissue from smooth muscle tissue.

Question 44

Larry's muscles weakened while he played tennis for hours on a hot summer afternoon. This inability to maintain intensity is defined as:

A) hypertonia.
B) atrophy.
C) hypotonia.
D) muscle fatigue.

Question 45

The increase in muscle tension that is produced by increasing the number of active motor units is called:

A) isotonic contraction.
B) recruitment.
C) muscle tone.
D) wave summation.

Question 46

What do skeletal muscle contractions share in common with smooth muscle contractions?

A) Both types of contractions do not require calcium ions for a contraction to occur.
B) Both types of contractions generate little force or a weak force.
C) Both types of contractions result from thick and thin filaments sliding past one another.
D) Both types of contractions consume very little ATP.

Question 47

In response to physical inactivity, we expect to see muscles:

A) hypertrophy.
B) increase numbers of myofibrils.
C) atrophy.
D) increase the diameter of the muscle fiber.

Question 48

What are the inward extensions of the sarcolemma into the muscle cell called? What function do these extensions serve?

Question 49

Latrotoxin, produced by the poisonous black widow spider, increases the release of acetylcholine. How do muscle cells respond?

A) Muscle cells will twitch irregularly when excess acetylcholine exists.
B) Muscle cells will experience fused or complete tetanus when excess acetylcholine exists.
C) Muscle cells will become paralyzed when excess acetylcholine exists.
D) Muscle cells will experience a longer latent period when excess acetylcholine exists.

Question 50

The type of contraction in which length of the muscle fibers do not change is called:

A) isotonic concentric.
B) tetany.
C) isotonic eccentric.
D) isometric.

Question 51

During the recovery period after exercise, we breathe deeper and faster. This increased rate of respiration is known as:

A) oxidative catabolism.
B) excess postexercise oxygen consumption (EPOC).
C) muscle fatigue.
D) lactic acid buildup.

Question 52

Describe the roles of contractile and regulatory proteins in the myofibril.

Question 53

When muscle fibers are stimulated so frequently they do not have an opportunity to relax, they are experiencing:

A) twitch.
B) wave summation.
C) unfused or incomplete tetanus.
D) fused or complete tetanus.

Question 54

Which fiber type helps Frances stand for hours in her job as a nurse?

A) type I fiber
B) type IIb fiber
C) type IIc fiber
D) type IIa fiber

Question 55

What type of contraction requires the greatest amount of tension?

A) isotonic eccentric contraction
B) isometric contraction
C) isotonic concentric contraction
D) miometric contraction

Question 56

Jorge tried to pick up his sofa but discover that it is much heavier than he expected. What must occur in the muscle to increase tension so he can pick up this heavy piece of furniture?

A) tetanic spasm
B) pliometric contraction
C) isotonic eccentric contractions
D) recruitment of additional motor units

Question 57

A single motor neuron together with all the skeletal muscle fibers it innervates is called a:

A) synaptic cleft.
B) motor unit.
C) neuromuscular junction.
D) motor end plate.

Question 58

Clostridium botulinum is a bacterium that produces botulinum toxin that inhibits the release of acetylcholine. Which description best fits how muscle cells will respond to a lack of acetylcholine?

A) Muscle cells will produce greater tension when there is a lack of acetylcholine.
B) Muscle cells will become paralyzed when there is a lack of acetylcholine.
C) Muscle cells will experienced fused or complete tetanus when there is a lack of acetylcholine.
D) Muscle cells will produce sustained contractions without relaxation when there is a lack of acetylcholine.

Question 59

Type I fibers lack:

A) a blood supply.
B) myoglobin.
C) mitochondria.
D) speed.

Question 60

Define excitability.

Question 61

List and describe the types of contractile and regulatory proteins found in a thin filament.

Question 62

Briefly discuss the role of the myosin heads in the sliding filament mechanism of muscle contraction.

Question 63

The function of the sarcoplasmic reticulum (SR) is to store and release calcium ions.

Question 64

Explain the role of acetylcholine in the excitation phase of excitation ^-contraction coupling.

Question 65

Describe the role of calcium in the regulation of the troponin ^-tropomyosin complex.

Question 66

Contractility is the ability of a muscle to shorten.

Question 67

Describe the bands that create the light and dark areas of skeletal muscle fibers known as striations.

Question 68

Determine the type of muscle contraction needed to lower a heavy bowling ball down by your side so you can roll it down the lane.

Question 69

Explain where sodium and potassium ions are relative to a muscle cell during resting membrane potential.

Question 70

What is the function of the sarcoplasmic reticulum?

Question 71

Skeletal muscle fibers possess intercalated discs.

Question 72

Describe the events of the relaxation period of a muscle twitch.

Question 73

How does hypertrophy change a muscle? Briefly explain.

Question 74

Explain how a sarcomere is affected when thin filaments slide past thick filaments during muscle contraction.

Question 75

Discuss the type of contractions produced by type I muscle fibers.

Question 76

Describe the synaptic cleft.

Question 77

Explain why myoglobin is useful.

Question 78

Summarize the steps of the crossbridge cycle.

Question 79

Determine how muscles are affected if the muscle receives stimulations so frequently that it has no opportunity to relax between them.

Question 80

Explain the role sodium ions play in the depolarization stage of the action potential.