Mastering Chapter 10

Interactions between actin and myosin filaments of the sarcomere are responsible for
muscle contraction

The area in the center of the A band that contains no thin filaments is the
H band

The thin filaments of striated muscle are made primarily of which protein(s)?
Answers!!
actin
nebulin
tropomyosin
troponin
All of the answers are correct.

The complex of a transverse tubule and two adjacent terminal cisternae is known as a ________.
triad

The action potential is conducted into a skeletal muscle fiber by
transverse tubules

Triggering of the muscle action potential occurs after
acetylcholine binds to chemically-gated channels in the end plate membrane

Active sites become exposed when calcium ions bind to ________.
troponin

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

The type of contraction in which the muscle fibers do not shorten is called
isometric

Creatine phosphate
acts as an energy reserve in muscle tissue

Which of the following is a recognized function of skeletal muscle?
Answers!!!
produce movement
maintain posture
maintain body temperature
guard body entrances and exits
All of the answers are correct.

The dense layer of connective tissue that surrounds an entire skeletal muscle is the
epimysium

The delicate connective tissue that surrounds the skeletal muscle fibers and ties adjacent muscle fibers together is the
endomysium

The bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone is called a(n)
tendon

An ________ can be described as a broad tendinous sheet.
aponeurosis

Interactions between actin and myosin filaments of the sarcomere are responsible for
muscle contraction

The advantage of having many nuclei in a skeletal muscle fiber is
the ability to produce large amounts of the muscle proteins needed for growth and repair.

The repeating unit of a skeletal muscle fiber is the
sarcomere

Which of the following best describes the term sarcoplasmic reticulum?
storage and release site for calcium ions

Cross-bridges are portions of
myosin molecules

At rest, the tropomyosin molecule is held in place by
troponin molecules

Each thin filament consists of
two actin protein strands coiled helically around each other

Which statement about the microscopic anatomy of skeletal muscle fibers is true?
Tubular extensions of the sarcolemma penetrate the fiber transversely.
Each fiber has many nuclei.
Cross striations result from the lateral alignment of thick and thin filaments.
Muscle fibers are continuous from tendon to tendon.
All of the answers are correct.

The protein that regulates muscle contraction by controlling the availability of active sites on actin is called ________.
tropomyosin

Thick filaments are made of the protein ________.
myosin

Stem cells located between the endomysium and sarcolemma that function in the repair of damaged muscle tissue are called ________.
myosatellite cells

In response to action potentials arriving along the transverse tubules, the sarcoplasmic reticulum releases
calcium ions

Each skeletal muscle fiber is controlled by a motor neuron at a single
neuromuscular junction

Active sites on the actin become available for binding after
calcium binds to troponin

The action potential is conducted into a skeletal muscle fiber by
transverse tubules

The most important factor in decreasing the intracellular concentration of calcium ion after contraction is
active transport of calcium into the sarcoplasmic reticulum

Which of the following become connected by myosin cross-bridges during muscle contraction?
thin filaments and thick filaments

In a sarcomere, cross-bridge attachment occurs specifically in the
zone of overlap

When acetylcholine binds to receptors at the motor end plate, the end plate membrane becomes
more permeable to sodium ions

Synaptic vesicles contain neurotransmitters that are released by ________ when the action potential arrives.
exocytosis

Active sites become exposed when calcium ions bind to ________.
troponin

Cross bridge detachment is caused by ________ binding to the myosin head.
ATP

If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called
wave summation

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

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

A weight-lifter strains to lift a heavy weight and there is no movement of the person’s arms holding on to the weight. This type of contraction is called a/an ________ contraction.
isometric

In which of the following would the motor units have the fewest muscle fibers?
muscles that control the eyes

A single contraction-relaxation cycle in a muscle fiber produces a ________.
twitch

During the Cori cycle, in the liver
glucose is produced from lactic acid.

A resting muscle generates most of its ATP by
aerobic metabolism of fatty acids

Creatine phosphate
acts as an energy reserve in muscle tissue.

After heavy exercise, if energy reserves in a muscle are depleted, ________ occurs.
an oxygen debt

At peak levels of muscle exertion the mitochondria can supply
only about one-third of the energy required by the muscle.

Which of the following hormones directly stimulates growth of muscle tissue, leading to increased muscle mass?
testosterone

Decreased blood flow to a muscle could result in all of the following, except
Answer: an increase in intracellular glycogen

muscle fatigue.
an increase in intracellular lactic acid.
a shift to anaerobic glycolysis.
an oxygen debt.

Heat energy produced from muscle contraction is released by the ________ system.
integumentary

The type of muscle fiber that is most resistant to fatigue is the ________ fiber.
slow

Fast fibers
have low resistance to fatigue and have quick twitches.

During activities requiring aerobic endurance
most of the muscle’s energy is produced in mitochondria.

When comparing slow muscle fibers to fast muscle fibers, slow fibers
have much smaller fiber diameters.
generate much less tension.
are rich in the red protein myoglobin.
take about three times as long to reach peak tension.
All of the answers are correct.

Muscular force can be adjusted to match different loads by
involving more muscle fibers in the contraction.
varying the frequency of action potentials in motor neurons.
recruiting larger motor units.
recruiting more motor units.
All of the answers are correct.

Which of the following best describes the term Z line?
thin filaments are anchored here

Which of the following is NOT a major function of skeletal muscle?
a. Maintaining body temperature
b. Lining hollow organs
c. Maintaining posture
d. Storing nutrient reserves

Answer: B

Which activity would be more likely to create an oxygen debt: swimming laps or lifting weights?
Lifting weights

How would a drug that blocks acetylcholine release affect muscle contraction?
Contraction would be prevented

What statements below are false with regard to the contraction of skeletal muscle?
Through concentric contractions, the muscle does not change length

Which of the following describes the characteristics of slow muscle fibers?
Small diameter, rich in myoglobin and very vascular

How would severing the tendon attached to a muscle affect the muscles ability to move a body part?
No movement is possible without a muscle to bone connection

Which of the following describes the neuromuscular junction?
Special intercellular connection between axon branches and a skeletal muscle fiber

How are epimysium, perimysium, and endomysium interrelated?

With excitation-contraction coupling,
a motor neuron releases ACh, which allows an electrical event to be transferred to the muscular system

A motor unit is/are _____. You would need a small motor unit to control movement of the fingers _____.
muscle fibers controlled by a single motor neuron; because you need precise control

Myofibrils are organized into repeating subunits called _____.
sarcomeres

Why does skeletal muscle appear striated when viewed through a microscope?
Z lines and myosin filaments align within a muscle fiber

The A band comprises which of the following subunits?
M line, H band, and the zone of overlap

Where would you expect the greatest concentration of Ca2+ in resting skeletal muscle to be?
in cisternae of the sarcoplasmic reticulum

In what ways does the appearance of a sarcomere change during contraction of a skeletal muscle fiber?
Z lines move closer together; I bands and H bands get smaller

_____ predominate in the large leg muscles of someone who excels at endurance activities, such as cycling. This is because _____.
Slow fibers; they have extensive capillary networks and much myoglobin

What is the mechanism that is primarily responsible for ATP production at peak levels of activity?
glycolysis in the cytoplasm

Why does a muscle that has been overstretched produce less tension?
Few cross-bridges form, causing weak contraction

What would you expect to happen to a resting skeletal muscle if the sarcolemma suddenly became very permeable to Ca2+?
increased strength of contraction, decreased ability to relax

Predict what would happen to muscles if a pesticide that inhibits acetylcholinesterase were present at the motor end plate.
Muscle would contract repeatedly

What feature of cardiac muscle tissue allows the heart to act as a functional syncytium?
gap junctions

Smooth muscle can contract over a wider range of resting lengths than skeletal muscle can. Why?
Actin and myosin filament arrangement is less organized in smooth muscle

What structural characteristics distinguish cardiac muscle tissue from skeletal muscle tissue? Cardiac muscle cells _____.
have intercalated discs, short T tubules, and no triads

Two cardiologists are talking about functional characteristics of cardiac muscle tissue. Which of the following descriptions would they use?
special gap junctions, intrinsic conduction system allows contraction without neural stimulation

Why are cardiac and smooth muscle contractions more affected by changes in extracellular Ca2+ than skeletal muscle contractions?
Most of the calcium for contractions comes from extracellular fluid

Why would a sprinter experience muscle fatigue before a marathon runner?
Sprinting involves anaerobic endurance, whereas running a marathon depends more upon availability of substrates for aerobic respiration

Excitation contraction coupling
1. Neural control
2. Excitation
3. Release of calcium ions
4. Contraction cycle begins
5. Sarcomere shortening
6. Generation of muscle tension

Contraction cycle
1. Contraction cycle begins
2. Active site exposure
3. Cross bridge formation
4. Myosin head pivoting
5. Cross bridge detachment
6. Myosin deactivation

Initiate a muscle contraction
1. ACh released
2. Action potential reaches T tubule
3. Sarcoplasmic reticulum releases Ca2+
4. Active site exposure and cross-bridge formation
5. Contraction cycle begins

End a muscle contraction
1. ACh is broken down
2. Sacroplasmic reticulum reabsorbs Ca2+
3. Active sites covered and cross bridge formation ends
4. Contraction ends
5. Muscle relaxation occurs

Skeletal muscle is responsible for all of the following EXCEPT
production of vitamin D

Skeletal muscle functions in
Maintaining body temperature

What is the functional unit of the muscle fiber
Sarcomere

What is the membranous network that surrounds each myofibril
Sarcoplasmic reticulum

The command to contract is conducted throughout the muscle fiber by the
Transverse tubules

The part of the sarcomere that contains thick filaments but no thin filaments is the
H band

Z lines
Mark the boundaries between adjacent sarcomeres

For tropomyosin to be shifted off its position covering the active sites of G actin molecules, calcium ions must bind to which structure?
Troponin

Which of the following descriptions of sarcomere components is FALSE?
The I band contains the zone of overlap at its center

When Jennifer looks through the microscope at skeletal and cardiac muscle, she sees striations. What are these striations?
A bands and I bands

The junction between a muscle cell and the neuron innervating that cell is the
Neuromuscular junction

ACh is released from what structure
Synaptic terminal

Which of the following does NOT happen when the action potential reaches the synaptic terminal?
Potassium ions flood the intercellular space

The binding of ACh to the motor end plate causes a change in membrane permeability to
Sodium

Which of the following events in a muscle contraction marks the beginning of the relaxation of the muscle cell
Detachment of cross bridges

What happens when the myosin head splits ATP into ADP and a phosphate group?
Myosin reactivation

Which of the following represents the correct sequence of events in a contraction cycle?
active-site exposure, cross-bridge attachment, pivoting, cross-bridge detachment, myosin reactivation

Action potentials must travel along which structure internal to the sarcolemma to cause the release of calcium ions from the sarcoplasmic reticulum?
T tubule

Which of the following statements about muscle contraction is FALSE?
When Ca2+ binds to a myosin head, it triggers the formation of a cross-bridge between myosin and actin.

In __________ contraction, the peak tension developed is less than the resistance, and the muscle elongates as a result of the contraction of another muscle or the pull of gravity.
an eccentric

Pushing against a locked door is an example of __________.
an isometric contraction

In which part of the sarcomere are myosin heads able to form cross-bridges with actin?
zone of overlap

When pyruvic acid is produced by anaerobic metabolism faster than it can be utilized, the surplus is converted to __________.
lactic acid

When energy reserves in a muscle are exhausted and lactic acid levels increase, __________ occurs.
fatigue

At peak levels of muscle exertion, mitochondrial activity can provide about only one-third of the ATP needed. The remainder is provided through __________.
glycolysis

Which of the following statements about muscle fatigue and the recovery period is FALSE?
Elevated oxygen demand in muscle tissue stops as soon as exercise activities cease.

During moderate and peak exertion of skeletal muscles, the body experiences a higher temperature because of which of the following?
the reduction of energy captured by skeletal muscles as ATP during moderate and peak exertion

Which type of muscle fiber allows for extremely quick contractions but fatigues quickly?
fast fiber

Which type of muscle fiber is supplied by extensive blood vessels?
slow fiber

What human muscles contain ONLY fast fibers?
hand muscles

The length of time muscular contraction can be supported by glycolysis is called __________.
anaerobic endurance

Which of the following features is found in cardiac muscle cells but NOT in skeletal and smooth muscle cells?
intercalated discs

Unique features of smooth muscles include which of the following?
plasticity

1. Which of the following is a recognized function of skeletal muscle? guard body entrances and exits, produce movement, maintain posture, maintain body temperature 2. Which of the following statements is incorrect? Skeletal muscles are responsible for the pumping action …

An action potential enters the depths of a muscle fiber by way of __________. diffusion the T tubules the calcium ion channels the sarcoplasmic reticulum the actin myofilament the T tubules Which structure do the calcium ions bind to when …

Which of the following is true concerning the anatomy of a skeletal muscle fiber? Myofibrils contain thick and thin filaments. The calcium that initiates skeletal muscle contraction is released from what structure(s)? terminal cisternae WE WILL WRITE A CUSTOM ESSAY …

Chapter 9 Muscles and Muscles Tissue (Mastering A&P) Which of the following is CORRECTLY paired? A. smooth muscle: striated B. cardiac muscle: nonstriated C. cardiac muscle: voluntary control D. skeletal muscle: voluntary control D. skeletal muscle: voluntary control What causes …

functions of muscle tissue (4) 1. movement 2. maintenance of posture 3. joint stabilization 4. heat generation special functional characteristics (4) 1. contractibility 2. excitability 3. extensibility 4. elasticity WE WILL WRITE A CUSTOM ESSAY SAMPLE ON ANY TOPIC SPECIFICALLY …

Which of the following is CORRECTLY paired? skeletal muscle: voluntary control Muscle tissue does NOT ________. product blood cells WE WILL WRITE A CUSTOM ESSAY SAMPLE ON ANY TOPIC SPECIFICALLY FOR YOU FOR ONLY $13.90/PAGE Write my sample Which type …

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