TEST 3 A&P Q62-176

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

ATP
immunoglobin
hemoglobin
myoglobin

myoglobin

The contractile units of skeletal muscles are ________.

T tubules
mitochondria
myofibrils
microtubules

myofibrils

What is the functional unit of a skeletal muscle called?

a myofibril
a myofilament
a sarcomere
the sarcoplasmic reticulum

a sarcomere

What is the functional role of the T tubules?

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

enhance cellular communication during muscle contraction

What is the role of calcium ions in muscle contraction?

bind to regulatory sites on troponin to remove contraction inhibition
increase levels of myoglobin
reestablish glycogen stores
form hydroxyapatite crystals

bind to regulatory sites on troponin to remove contraction inhibition

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 ________.

lactic acid
stearic acid
a strong base
hydrochloric acid

lactic acid

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

fatigue period
relaxation period
refractory period
latent period

refractory period

In an isotonic contraction, the muscle ________.

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

changes in length and moves the "load"

The muscle cell membrane is called the ________.

perimysium
sarcolemma
endomysium
epimysium

sarcolemma

Which of the following is the correct sequence of events for muscle contractions?

muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, sliding of myofilaments
neurotransmitter release, motor neuron action potential, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke
motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments
neurotransmitter release, muscle cell action potential, motor neuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke

motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments

The giant protein titin maintains the organization of the ________ assisting in muscle stretching.

I band
A band
M line
Z disc

a band

Which of the following statements is true?

Cardiac muscle cells have many nuclei.
Smooth muscle cells have T tubules.
Cardiac muscle cells are found in the heart and large blood vessels.
Skeletal muscle cells are long and cylindrical with many nuclei.

Skeletal muscle cells are long and cylindrical with many nuclei.

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

glycolysis
the electron transport chain
hydrolysis
the citric acid cycle

glycolysis

Muscle tone is ________.

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

a state of sustained partial contraction

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

acetylcholinesterase destroying the ACh
the action potential stops going down the overloaded T tubules
the tropomyosin blocking the myosin once full contraction is achieved
calcium ions returning to the terminal cisternae

acetylcholinesterase destroying the ACh

Which of the following statements is most accurate?

Muscle tension remains relatively constant during isotonic contraction.
T tubules may be sliding during isotonic contraction.
Myofilaments slide during isometric contractions.
The I band lengthens during isotonic contraction.

Muscle tension remains relatively constant during isotonic contraction.

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

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

no muscle tension could be generated

What part of the sarcolemma contains acetylcholine receptors?

any part of the sarcolemma
part adjacent to another muscle cell
motor end plate
end of the muscle fiber

motor end plate

Gary was injured in an automobile accident that severed the motor neurons innervating his quadriceps. Even though he has had extensive physical therapy, he is still suffering muscle atrophy. Why is the therapy not working?

In denervation (disuse) atrophy, fibrous connective tissue replaces the muscle tissue that was lost. When atrophy is complete, fibrous tissue cannot be reversed to muscle tissue.
In Duchenne muscular dystrophy, the muscle enlarges due to fat and connective tissue, but the muscle fibers atrophy and degenerate irreversibly.
In myotonic dystrophy, there is a gradual loss of muscle mass as muscle proteins degrade faster than they can be replaced.
In myasthenia gravis, fibrous connective tissue replaces the muscle tissue that was lost. When atrophy is complete, fibrous tissue cannot be reversed to muscle tissue.
In sarcopenia, there is a gradual loss of muscle mass as muscle proteins degrade faster than they can be replaced.

In denervation (disuse) atrophy, fibrous connective tissue replaces the muscle tissue that was lost. When atrophy is complete, fibrous tissue cannot be reversed to muscle tissue.

Aaron arrived at the hospital with the following symptoms: drooping eyelids; fatigue and weakness of his muscles; and difficulty talking, breathing, and swallowing. What was his diagnosis?

Myasthenia gravis
Myotonic dystrophy
Duchenne muscular dystrophy
Disuse atrophy
Sarcopenia

Myasthenia gravis

The nurse encourages the patient to do his own activities of daily living such as bathing, eating, dressing, and toileting activities. How do these activities promote physical conditioning?

The contraction of the muscles in these activities reverses sarcopenia and rebuilds muscle mass.
The contraction of the muscles in these activities helps maintain the shape, size, and strength of muscles, as well as joint mobility.
It does not. Only weight-bearing exercises maintain the shape, size and strength of muscles.
The contraction of the muscles in these activities reverses myotonic dystrophy and rebuilds muscle mass.

The contraction of the muscles in these activities helps maintain the shape, size, and strength of muscles, as well as joint mobility.

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

True
False

true

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

True
False

true

What is the role of tropomyosin in skeletal muscles?

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

Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.

What does excess postexercise oxygen consumption represent?

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

the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used

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.

relaxation
latent
refractory
contraction

latent

What is the primary function of wave summation?

produce smooth, continuous muscle contraction
prevent muscle relaxation
increase muscle tension
prevent muscle fatigue

produce smooth, continuous muscle contraction

Rigor mortis occurs because ________.

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

no ATP is available to release attached actin and myosin molecules

Which of the choices below does not describe how excess postexercise oxygen consumption (oxygen deficit) restores metabolic conditions?

resynthesizes creatine phosphate and ATP in muscle fibers
converts lactic acid back into glycogen stores in the liver
increases the level of lactic acid in the muscle
replaces the oxygen removed from myoglobin

increases the level of lactic acid in the muscle

Which of the following is not a connective tissue sheath that wraps individual muscle fibers?

aponeurosis
perimysium
endomysium
epimysium

aponeurosis

Which of the following is not a role of ionic calcium in muscle contraction?

removes contraction inhibitor
binds with troponin
triggers neurotransmitter secretion
activates epinephrine released from adrenal gland

activates epinephrine released from adrenal gland

The sliding filament model of contraction involves ________.

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

actin and myosin sliding past each other and partially overlapping

What is the most distinguishing characteristic of muscle tissue?

the diversity of activity of muscle tissue
the ability to transform chemical energy into mechanical energy
the design of the fibers
the ability to respond to nervous stimulation

the ability to transform chemical energy into mechanical energy

Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers?

a long, relaxing swim

Which organelle contains the contractile elements found in skeletal muscle?

sarcolemma
glycosome
sarcoplasmic reticulum
myofibril

myofibril

Which protein inhibits interaction between actin and myosin to prevent skeletal muscle contraction; and which ions remove the inhibition?

actin; calcium ions
tropomyosin; calcium ions
myosin; sodium ions
troponin; sodium ions

tropomyosin; calcium ions

Excitation-contraction coupling includes all EXCEPT which of the following events?

release of acetylcholine from axon terminals at the neuromuscular junction
binding of calcium ions to troponin, which removes the blocking action of tropomyosin
propagation of an action potential along the sarcolemma and down T tubules
release of calcium ions from the terminal cisterns

release of acetylcholine from axon terminals at the neuromuscular junction

What is a cross bridge cycle?

It is the cycle in which motor units are recruited from small to large, in order to produce gradual increases in force.
It is a cycle of repeated stimuli resulting in summation of muscle twitches.
It is the cycle by which the sarcolemma is repeatedly depolarized and repolarized.
It is the cycle in which an energized myosin head binds to actin and performs a power stroke, then binds to ATP in order to detach and re-energize.

It is the cycle in which an energized myosin head binds to actin and performs a power stroke, then binds to ATP in order to detach and re-energize.

Which pathway for regenerating ATP provides the majority of the energy used for muscle activity during 30 minutes of light to moderate exercise?

direct phosphorylation of ADP by creatine phosphate
anaerobic glycolysis
use of stored ATP
aerobic respiration

aerobic respiration

Which of the following factors influence the velocity and duration of muscle contraction?

muscle fiber size
load placed on the muscle
length of muscle fibers activated
frequency of stimulation

load placed on the muscle

Which muscle fiber type is best suited for endurance activities, such as long-distance jogging?

fast glycolytic fibers
slow glycolytic fibers
slow oxidative fibers
fast oxidative fibers

slow oxidative fibers

What is the type of chemical reaction used to rebuild ADP into ATP?

rehydration synthesis
dehydration synthesis
hydrolysis

dehydration synthesis

Which of the following processes produces molecules of ATP and has two pyruvic acid molecules as end products?

Krebs cycle and oxidative phosphorylation
hydrolysis of creatine phosphate
glycolysis

glycolysis

Which of the following processes produces 36 ATP?

glycolysis
hydrolysis of creatine phosphate
Krebs cycle and oxidative phosphorylation

Krebs cycle and oxidative phosphorylation

The "rest and recovery" period, where the muscle restores depleted reserves, includes all of the following processes EXCEPT __________.

ATP is used to rephosphorylate creatine into creatine phosphate.
Glycogen is synthesized from glucose molecules.
Oxygen rebinds to myoglobin.
Pyruvic acid is converted back to lactic acid.

Pyruvic acid is converted back to lactic acid.

Which type of muscle fiber has a large quantity of glycogen and mainly uses glycolysis to synthesize ATP?

white fast twitch fibers
red slow twitch fibers

white fast twitch fibers

The connective tissue sheaths of skeletal muscle, in order from internal to external, are the ________.

endomysium, perimysium, and epimysium
endomysium, epimysium, and perimysium
perimysium, endomysium, and epimysium
epimysium, perimysium, and endomysium
epimysium, endomysium, and perimysium

endomysium, perimysium, and epimysium

Choose the FALSE statement.

Skeletal muscle cells are multinucleated.
Skeletal muscle cells use creatine phosphate instead of ATP to do work.
Skeletal muscle cells have glycosomes.
Skeletal muscle cells have T tubules.
Skeletal muscle cells contain myoglobin.

Skeletal muscle cells use creatine phosphate instead of ATP to do work.

The smallest contractile unit of a muscle fiber is ________.

the myofilament
troponin
the sarcomere
the elastic filament

the sarcomere

Thick myofilaments are made of ________.

actin
myosin
troponin
tropomyosin

myosin

The major role of the sarcoplasmic reticulum is to regulate ________.

extracellular levels of Ca2+
intracellular levels of Na+
intracellular levels of Ca2+
extracellular levels of Na+

intracellular levels of Ca2+

The distance between Z discs ________ during muscle contraction.

decreases
increases
decreases and then increases
stays the same

decreases

The sliding filament model of contraction states that ________.

during contraction the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments overlap to a greater degree
during contraction the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments no longer overlap
during contraction the thin myofilaments slide past T tubules so that the Z discs are overlapping
during contraction the thin myofilaments slide past the thick myofilaments so that calcium ions can be released from the sarcoplasmic reticulum

during contraction the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments overlap to a greater degree

The first step toward generating a skeletal muscle contraction is ________.

a rise in intracellular Ca2+ levels
binding of the myosin heads to actin
binding of ATP to the myosin heads
stimulation of the muscle by a nerve ending

stimulation of the muscle by a nerve ending

A muscle that is lengthening while it produces tension is performing a(an) ________ contraction.

concentric
eccentric
isometric
maximal

eccentric

The response of a motor unit to a single action potential of its motor neuron is called ________.

a muscle twitch
a tetanic contraction
wave summation
recruitment

a muscle twitch

When muscle cells break down glucose to generate ATP under oxygen deficient conditions, they will form ________.

fatty acids
glycogen
glucose
lactic acid

lactic acid

The force of a muscle contraction is NOT affected by __________.

the size of the muscle fibers stimulated
the degree of muscle stretch
the number of muscle fibers stimulated
the frequency of the stimulation
the amount of ATP stored in the muscle cells

the amount of ATP stored in the muscle cells

Slow oxidative muscle fibers are best suited for ________.

hitting a baseball
lifting heavy weights at the gym
running a marathon
running a 100-yard dash

running a marathon

Which of the following is TRUE?

Skeletal muscle cells have one nucleus, but smooth muscle cells are multinucleated.
Skeletal muscle fibers tend to be shorter than smooth muscle fibers.
Skeletal muscle lacks the coarse connective tissue sheaths that are found in smooth muscle.
Skeletal muscle fibers contain sarcomeres; smooth muscle fibers do not.

Skeletal muscle fibers contain sarcomeres; smooth muscle fibers do not.

Binding of calcium to calmodulin is a step in excitation-contraction coupling of ________ cells.

cardiac and visceral smooth muscle
cardiac muscle
skeletal muscle
smooth muscle

smooth muscle

A muscle cell runs out of ATP. Even though these are cyclic reactions, what step of the cross bridge cycle given is most directly inhibited or terminated?

cross bridge formation
cocking of myosin head
cross bridge detachment
the power stroke

cross bridge detachment

A person dies and within hours, the skeletal muscles develop a locked contraction known as rigor mortis. Calcium ions leak from the sarcoplasmic reticulum into cytoplasm. From your knowledge of cross-bridge cycling, what best explains this rigor?
Cross bridge formation cannot occur. ATP, which is only produced during life, must to be bound to the myosin head to permit cross bridging.
The cross bridge is locked up because ATP directly attaches myosin to actin.
Cross bridge detachment cannot occur. Detachment requires ATP, which is only produced during life.
The cross bridge is locked up because the power stroke requires ATP, which is only produced during life.

Cross bridge detachment cannot occur. Detachment requires ATP, which is only produced during life.

Which of the following is true concerning the anatomy of a skeletal muscle fiber?

Myofibrils contain thick and thin filaments.
T tubules are extensions of the sarcoplasmic reticulum.
The sarcolemma is the muscle fiber's cytoplasm.
A triad consists of a T tubule and the nearby sarcolemma.

Myofibrils contain thick and thin filaments.

The calcium that initiates skeletal muscle contraction is released from what structure(s)?

T tubules
sarcolemma
terminal cisternae
sarcomeres

terminal cisternae

Which of the following are composed of myosin?

tropomyosin
thick filaments
intermediate filaments
thin filaments

thick filaments

In muscle fibers, which regulatory protein blocks the attachment of myosin heads to actin?

thick filaments
calcium
tropomyosin
acetylcholinesterase

tropomyosin

What event most directly triggers the release of calcium from the terminal cisternae?

action potential propagating down the T tubule
action potential propagating toward the axon terminal
movement of tropomyosin away from the active sites on actin
cross bridge formation between the thick and thin filaments

action potential propagating down the T tubule

How do calcium ions initiate contraction in skeletal muscle fibers?

Calcium ions provide the energy necessary for the myosin head power stroke.
Calcium ions bind to troponin, changing troponin's shape.
Calcium ion movement depolarizes the sarcolemma at the synaptic cleft.
Calcium ions bind to tropomyosin, exposing the active sites on actin.

Calcium ions bind to troponin, changing troponin's shape.

Which of the following best describes the events of "excitation" in "excitation-contraction coupling"?

movement of tropomyosin away from the active sites on actin
cross bridge formation
release of calcium from the terminal cisternae
propagation of the action potential along the sarcolemma

propagation of the action potential along the sarcolemma

Which of the following best describes the events of "contraction" in "excitation-contraction coupling"?

cross bridge formation
propagation of the action potential along the sarcolemma of the muscle fiber
release of calcium from the terminal cisternae
sliding of myofilaments

cross bridge formation

Peristalsis is characteristic of smooth muscle.

True
False

true

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

True
False

true

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

True
False

true

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

the trigger for contraction is a rise in intracellular calcium
actin and myosin interact by the sliding filament mechanism
the site of calcium regulation differs
ATP energizes the sliding process

the site of calcium regulation differs

Which of the following is true about smooth muscle contraction?

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

Certain smooth muscle cells can actually divide to increase their numbers.

Smooth muscle is characterized by all of the following except ________.

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

there are more thick filaments than thin filaments

Of the following muscle types, which has only one nucleus, no sarcomeres, and rare gap junctions?

cardiac muscle
multiunit smooth muscle
visceral smooth muscle
skeletal muscle

multiunit smooth muscle

Which of the following statements is false or incorrect?

Cardiac muscle fibers can use lactic acid to make ATP.
Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP.
Under normal resting conditions, cardiac muscle tissue contracts and relaxes about 75 times per minute.
Cardiac muscle contracts when stimulated by its own autorhythmic muscle cells.

Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP.

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

True
False

true

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

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

They exhibit spontaneous action potentials.

What special feature of smooth muscle allows it to stretch without immediately resulting in a strong contraction?

stress-relaxation response
slow, prolonged contractile activity
smooth muscle tone
low energy requirements

stress-relaxation response

The type of muscle found in the walls of most hollow organs is ________.

cardiac muscle
skeletal muscle
multi unit smooth muscle
unitary smooth muscle

unitary smooth muscle

Isometric contraction leads to movement of a load.

True
False

false

Cardiac muscle makes most of its ATP via anaerobic pathways.

True
False

false

Duchenne muscular dystrophy could theoretically be cured if a technique was developed that would _________.

strengthen the dystrophin proteins that are present in the patient's muscle fibers
double the existing number of dystrophin molecules in the patient's muscle fibers
strengthen the thick and thin filaments in the patient's muscle fibers
none of the above

none of the above

Which muscle cells have the greatest ability to regenerate?

no muscle can regenerate
smooth
cardiac
skeletal

smooth

Cardiac muscle has a limited regenerative capacity.

True
False

true

Which of the following is not a component of the standard treatment for muscle strain?

elevation of the limb
rest of the muscle
stretching of the muscle
ice on the muscle

stretching on muscle

Smooth muscles are able to regenerate throughout life.

True
False

true

________ are the muscles primarily responsible for producing a particular movement.

Synergists
Fixators
Agonists
Antagonists

agonists

Which functional group has the major responsibility for producing a specific movement?

agonists
fixators
synergists
antagonists

agonists

What is a muscle that provides the major force for producing a specific movement called?

an antagonist
a fixator
an agonist
a synergist

an agonist

What type of muscle assists an agonist by causing a like movement or by stabilizing a joint over which an agonist acts?

a synergist
an antagonist
an agonist
a prime mover

a synergist

Which generalization concerning movement by skeletal muscles is not true?

The bones serve as levers.
Muscles produce movement by pulling on bones.
During contraction the two articulating bones move equally.
The movements produced may be of graded intensity.

During contraction the two articulating bones move equally.

Muscles are only able to pull, they never push.

True
False

ture

Muscles that help maintain upright posture are fixators.

True
False

true

Muscles that help to maintain posture are often called synergists.

True
False

false

Which of the following is NOT used as a criterion for naming muscles?

the location of the muscle
the number of origins for the muscle
the shape of the muscle
whether the muscle is controlled by the involuntary or voluntary nervous system
the locations of the muscle attachments

whether the muscle is controlled by the involuntary or voluntary nervous system

Which of the following muscles is named for its origin and insertion?

trapezius
sternocleidomastoid
deltoid
gluteus maximus

sternocleidomastoid

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