Deck 9: Muscles and Muscle Tissue

Question 1

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

Answer 1

False

Question 2

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.

Answer 2

True

Question 3

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

Answer 3

True

Question 4

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

Question 5

A resting potential is caused by a difference in the concentration of certain ions inside and outside the cell.

Question 6

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

Question 7

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

Question 8

Peristalsis is characteristic of smooth muscle.

Question 9

Cardiac muscle has a limited regenerative capacity.

Question 10

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

Question 11

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

Question 12

Once a motor neuron has fired,all the muscle fibers in a muscle contract.

Question 13

Eccentric contractions are more forceful than concentric contractions.

Question 14

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

Question 15

During isometric contraction,the energy used appears as movement.

Question 16

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

Question 17

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

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

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

Question 21

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

Question 22

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 23

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

Question 24

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.

Question 25

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

Question 26

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

Question 27

What is the functional unit of a skeletal muscle called?

A)a myofibril
B)the sarcoplasmic reticulum
C)a sarcomere
D)a myofilament

Question 28

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

Question 29

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

Question 30

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

Question 31

What structure in skeletal muscle cells functions in calcium storage?

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

Question 32

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

Question 33

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

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

Question 34

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

Question 35

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

Question 36

Which muscle cells have the greatest ability to regenerate?

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

Question 37

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

Question 38

The contractile units of skeletal muscles are ________.

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

Question 39

Which of the following surrounds the individual muscle cell?

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

Question 40

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

Question 41

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

Question 42

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

Question 43

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

Question 44

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

Question 45

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

Question 46

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.

Question 47

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

Question 48

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

Question 49

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.

Question 50

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

Question 51

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

Question 52

Muscle tissue has all of the following properties except ________.

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

Question 53

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

Question 54

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.

Question 55

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.

Question 56

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

Question 57

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

Question 58

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

Question 59

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

Question 60

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.

Question 61

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.

Question 62

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

Question 63

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

Question 64

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

Question 65

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

Question 66

The enzyme ________ is present in the synaptic cleft.Its activity stops the neutotransmitters stimulation.

Question 67

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

Question 68

Only ________ muscle cells are multinucleated.

Question 69

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

Question 70

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

Question 71

Only ________ muscle cells commonly branch.

Question 72

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.

Question 73

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

Question 74

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.

Question 75

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

Question 76

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.

Question 77

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.

Question 78

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

Question 79

A smooth,sustained contraction from rapid stimulation is called ________.

Question 80

Which cells help repair injured skeletal muscle fibers and allows regeneration of dead skeletal muscle?