Deck 9: Muscles and Muscle Tissue

Question 1

One of the functions of skeletal muscle contraction is production of heat.

Answer 1

True

Question 2

When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands do not diminish in length.

Answer 2

True

Question 3

Cells of unitary smooth muscle are found in the longitudinal and circular muscle layers of the intestine.

Answer 3

True

Question 4

Smooth muscles relax when intracellular Ca2+ levels drop but may not cease contractions.

Question 5

Muscle contraction will always promote movement of body parts regardless of how they are attached.

Question 6

The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily.

Question 7

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 serves as a contraction inhibitor by blocking the actin binding sites on the myosin molecules.
C) Tropomyosin is the receptor for the motor neuron neurotransmitter.
D) Tropomyosin is the chemical that activates the myosin heads.

Question 8

Cardiac muscle has a limited regenerative capacity.

Question 9

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.

Question 10

Peristalsis is characteristic of smooth muscle.

Question 11

Muscle cells store more creatine phosphate than ATP resulting in the muscle having a reserve source of energy.

Question 12

A contraction in which the muscle does not shorten but its tension increases is called isometric contraction.

Question 13

A skeletal muscle contracts with varying force and length of time in response to the body's needs at the time.

Question 14

During isometric contraction, the energy used appears as movement.

Question 15

The force of muscle contraction is controlled by multiple motor unit summation or recruitment.

Question 16

The thin filaments (actin) contain a polypeptide subunit G actin that bears active sites for myosin attachment.

Question 17

Although there are no sarcomeres, smooth muscle still possesses thick and thin filaments.

Question 18

Muscle tone is the small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units.

Question 19

A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate.

Question 20

Excitability is the ability of a cell to receive and respond to stimulus by changing its membrane potential.

Question 21

What structure in skeletal muscle cells functions in calcium storage?

A) myofibrillar network
B) intermediate filament network
C) mitochondria
D) sarcoplasmic reticulum

Question 22

Which of the following is a factor that affects the velocity and duration of muscle contraction?

A) size of the muscle fibers stimulated
B) muscle length
C) load on the fiber
D) number of muscle fibers stimulated

Question 23

During vigorous exercise, there may be insufficient oxygen available to completely break down pyruvic acid for energy. As a result, the pyruvic acid is converted to .

A) stearic acid
B) lactic acid
C) hydrochloric acid
D) a strong base

Question 24

Myoglobin .

A) is a protein involved in the direct phosphorylation of ADP
B) produces the end plate potential
C) stores oxygen in muscle cells
D) breaks down glycogen

Question 25

The contractile units of skeletal muscles are .

A) myofibrils
B) mitochondria
C) microtubules
D) T tubules

Question 26

When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods?

A) refractory period
B) latent period
C) relaxation period
D) fatigue period

Question 27

Which of the following surrounds an individual muscle cell?

A) endomysium
B) epimysium
C) perimysium
D) fascicle

Question 28

Sarcomeres are functional units of _ muscle.

A) smooth
B) cardiac
C) skeletal
D) B and C only

Question 29

Which of the following would be recruited later in muscle stimulation when contractile strength increases?

A) motor units with the longest muscle fibers
B) large motor units with small, highly excitable neurons
C) many small motor units with the ability to stimulate other motor units
D) motor units with larger, less excitable neurons

Question 30

Creatine phosphate functions in the muscle cell by .

A) inducing a conformational change in the myofilaments
B) forming a chemical compound with actin
C) storing energy that will be transferred to ADP to resynthesize ATP
D) forming a temporary chemical compound with myosin

Question 31

Rigor mortis occurs because .

A) sodium ions leak into the muscle causing continued contractions
B) proteins are beginning to break down, thus preventing a flow of calcium ions
C) no ATP is available to release attached actin and myosin molecules
D) the cells are dead

Question 32

What is the primary function of wave summation?

A) prevent muscle relaxation
B) prevent muscle fatigue
C) produce smooth, continuous muscle contraction
D) increase muscle tension

Question 33

The strongest muscle contractions are normally achieved by .

A) increasing stimulus above the threshold
B) increasing the stimulation up to the maximal stimulus
C) recruiting small and medium muscle fibers
D) increasing stimulus above the treppe stimulus

Question 34

Most skeletal muscles contain .

A) a predominance of slow oxidative fibers
B) muscle fibers of the same type
C) a predominance of fast oxidative fibers
D) a mixture of fiber types

Question 35

What is the functional role of the T tubules?

A) enhance cellular communication during muscle contraction
B) synthesize ATP to provide energy for muscle contraction
C) hold cross bridges in place in a resting muscle
D) stabilize the G and F actin

Question 36

What does excess postexercise oxygen consumption represent?

A) the amount of oxygen taken into the body immediately after the exertion
B) amount of oxygen needed for aerobic activity to accomplish the same amount of work
C) the amount of oxygen equal to the oxygen already used
D) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used

Question 37

The oxygen-binding protein found in muscle cells is _ .

A) immunoglobin
B) ATP
C) myoglobin
D) hemoglobin

Question 38

Which muscle cells have the greatest ability to regenerate?

A) cardiac
B) skeletal
C) smooth
D) no muscle can regenerate

Question 39

During muscle contraction, myosin cross bridges attach to which active sites?

A) Z discs
B) thick filaments
C) myosin filaments
D) actin filaments

Question 40

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) contraction
B) refractory
C) latent
D) relaxation

Question 41

The ability of muscle to shorten forcibly when adequately stimulated is known as _ _, and sets muscle apart from other tissue types.

A) extensibility
B) excitability
C) contractility
D) elasticity

Question 42

Which of the following statements is true?

A) Cardiac muscle cells are found in the heart and large blood vessels.
B) Cardiac muscle cells have many nuclei.
C) Striated muscle cells are long and cylindrical with many nuclei.
D) Smooth muscle cells have T tubules.

Question 43

An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is _ .

A) the electron transport chain
B) hydrolysis
C) glycolysis
D) the citric acid cycle

Question 44

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?

A) acetylcholinesterase breaks apart the ACh
B) the action potential stops going down the overloaded T tubules
C) calcium ions returning to the terminal cisternae
D) the tropomyosin blocking the myosin once full contraction is achieved

Question 45

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped, .

A) cross bridge attachment would be optimum because of all the free binding sites on actin
B) no muscle tension could be generated
C) ATP consumption would increase because the sarcomere is "trying" to contract
D) maximum force production would result because the muscle has a maximum range of travel

Question 46

Which of the following describes the cells of unitary smooth muscle?

A) They consist of muscle fibers that are structurally independent of each other.
B) They exhibit spontaneous action potentials.
C) They depend upon recruitment using the autonomic nervous system.
D) They are used for vision and hair raising.

Question 47

Which of the following is the correct order for the phases of a muscle twitch?

A) contraction, relaxation, latent
B) latent, contraction, relaxation
C) latent, relaxation, contraction
D) relaxation, contraction, latent

Question 48

What part of the sarcolemma contains acetylcholine receptors?

A) part adjacent to another muscle cell
B) any part of the sarcolemma
C) end of the muscle fiber
D) motor end plate

Question 49

Although all the anatomical parts of muscle work together to give it its characteristics, which of the following proteins listed below would be most associated with the characteristics of extensibility?

A) thick (myosin) filaments
B) acetylcholine receptors in the motor end plate
C) potassium (K+) leak channels
D) elastic (titin) filaments

Question 50

In an isotonic contraction, the muscle .

A) changes in length and moves the "load"
B) rapidly resynthesizes creatine phosphate and ATP
C) does not change in length but increases tension
D) never converts pyruvate to lactate

Question 51

Smooth muscle is characterized by all of the following EXCEPT _.

A) it appears to lack troponin
B) there are no sarcomeres
C) there are more thick filaments than thin filaments
D) there are noncontractile intermediate filaments that attach to dense bodies within the cell

Question 52

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) actin of thin filaments
B) the Na+-K+ pump
C) acetylcholine receptors in the motor end plate
D) elastic (titin) filaments

Question 53

Which of the following is true about smooth muscle?

A) Smooth muscle has well-developed T tubules at the site of invagination.
B) Certain smooth muscle cells can actually divide to increase their numbers.
C) Smooth muscle cannot stretch as much as skeletal muscle.
D) Smooth muscle, in contrast to skeletal muscle, cannot synthesize or secrete any connective tissue elements.

Question 54

The sliding filament model of contraction involves .

A) the Z discs sliding over the myofilaments
B) actin and myosin lengthening in order to slide past each other
C) actin and myosin sliding past each other and partially overlapping
D) the shortening of thick filaments so that thin filaments slide past

Question 55

The mechanism of contraction in smooth muscle is different from skeletal muscle in that _.

A) ATP energizes the sliding process
B) actin and myosin interact by the sliding filament mechanism
C) the site of calcium binding site differs
D) the trigger for contraction is a rise in intracellular calcium

Question 56

Of the following muscle types, which has the longest muscle cells and has obvious stripes called striations?

A) multiunit smooth muscle
B) cardiac muscle
C) skeletal muscle
D) visceral smooth muscle

Question 57

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

Question 58

What is the most distinguishing characteristic of muscle tissue?

A) It is composed of multiple cells working together.
B) the ability to transform chemical energy into mechanical energy to move the body
C) the ability to respond to nervous stimulation
D) its cells' inability to reproduce by mitosis

Question 59

Muscle tone is _ .

A) a state of sustained partial contraction
B) the ability of a muscle to efficiently cause skeletal movements
C) the feeling of well-being following exercise
D) the condition of athletes after intensive training

Question 60

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) thick (myosin) filaments
B) elastic (titin) filaments
C) potassium (K+) leak channels
D) voltage gated sodium channels

Question 61

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 A band to appear darker
C) the I bands to appear smaller
D) the I bands to appear wider

Question 62

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) weakness of muscle
B) dehydration with headache
C) seizures and uncontrollable muscle movement
D) coma and loss of voluntary muscle movement

Question 63

Exhaustion of glycogen storage within a muscle fiber would have the biggest effect on .

A) fast glycolytic fibers
B) fast oxidative fibers
C) slow oxidative fibers
D) both slow and fast oxidative fibers

Question 64

Of the following items listed below, which is the best description for why skeletal muscle stores glycogen?

A) Glycogen is part of muscles rigid supporting framework.
B) Glycogen provides a smooth surface for filaments to slide on.
C) The glycogen is an insulating layer that helps regulate body temperature.
D) Skeletal muscle is a heavy consumer of energy.

Question 65

Addition of more mitochondria to a muscle fiber will have the greatest effect on _ .

A) both slow and fast oxidative fibers
B) fast oxidative fibers
C) fast glycolytic fibers
D) slow oxidative fibers

Question 66

The end of the muscle that is attached to the part of the body in motion when a muscle contracts is called the
.

Question 67

The enzyme is present in the synaptic cleft at the neuromuscular junction. Its activity stops the neurotransmitters stimulation.

Question 68

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) Muscles will respond too quickly and cause a severe tremor.
B) Curare will only affect muscles with ACh receptors, paralyzing them.
C) Curare will only affect cardiac muscle, causing fibrillations of the heart.
D) Smooth muscles will become stimulated causing quick movement of nutrients through the digestive system.

Question 69

Reduction in blood flow to a muscle fiber would have the greatest effect on .

A) fast oxidative fibers
B) fast glycolytic
C) both slow and fast oxidative
D) slow oxidative fibers

Question 70

Which of the following statements best illustrates the fact that skeletal muscle is voluntary muscle?

A) Skeletal muscle appears striated due to the structure of the sarcomeres.
B) The shivering reflex aids in maintaining body temperature.
C) Skeletal muscle is wrapped in several layers of connective tissue. The deepest layer being the endomysium.
D) Skeletal muscle fibers are innervated by somatic motor neurons.

Question 71

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) generate and propagate action potential
C) produce movement through contractile force
D) produce relatively high amounts of ATP

Question 72

During development embryonic cells will fuse to form muscle fibers. This will result in .

A) the coordination of nerve signals to muscle fibers
B) interlocking of cells that can prevent the filaments from sliding
C) multinucleated muscle fibers that can extend as long as 30 centimeters
D) the striations that appear in skeletal and cardiac muscle tissues

Question 73

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) both fast glycolytic and fast oxidative fibers
C) fast oxidative fibers
D) fast glycolytic fibers

Question 74

Addition of more myoglobin to a muscle fiber would have the largest effect on .

A) fast glycolytic and fast oxidative fibers
B) fast glycolytic fibers only
C) fast oxidative and slow oxidative fibers
D) fast oxidative fibers only

Question 75

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) Calcium would be transported to the sarcoplasmic reticulum therefore contractions would cease.
B) The fiber would twitch uncontrollably due to excessive calcium bound to troponin.
C) Myosin would be able to bind to the exposed binding sites on thin filaments but it would not be able to detach.
D) No change would occur in a muscle that was relaxed to begin with.

Question 76

Only muscle cells are multinucleated.

Question 77

A potential benefit of recruiting slow oxidative fibers for contraction before recruiting fast oxidative and fast glycolytic fibers might be .

A) to allow for fine control with delicate contractile force with a small stimulus
B) 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
C) because they are slower to respond, slow oxidative fibers must be stimulated first in order to contract simultaneously with the faster fibers
D) 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.

Question 78

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) smooth muscle
B) cardiac muscle
C) striated muscle
D) skeletal muscle

Question 79

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, they only begin aerobic respiration by the time the run has finished.
C) Slow oxidative fibers are recruited last and have only started to work at completion of the run.
D) The runners' use of stored oxygen, glucose, and creatine phosphate is being replenished and this requires a prolonged increase of oxygen intake.

Question 80

Troponin, a major protein in thin filaments, is a globular protein with three polypeptide subunits. Which of the following is NOT a function of the troponin?

A) One subunit binds tropomyosin and helps position it on actin.
B) One subunit binds to calcium ions.
C) One subunit binds to potassium ions.
D) One subunit attaches troponin to actin.