Biology of Muscles

Question 1

Which of the following is a recognized function of skeletal muscle?

• produce movement
• maintain body temperature
• guard body entrances and exits
• maintain posture
• all of the above

Answer 1

• all of the above

Question 2

Which of the following is not a function of smooth muscle tissue?

• epimysium.
• tendon.
• perimysium.
• endomysium.
• fascicle.

Answer 2

• epimysium.

Question 3

The plasma membrane of skeletal muscle is called the..

• sarcolemma.
• sarcomere.
• sarcoplasm.
• sarcoplasmic reticulum.
• sarcosome.

Answer 3

• sarcolemma.

Question 4

Which of the following best describes the term sarcoplasmic reticulum?

• largely made of myosin molecules
• protein that accounts for elasticity of resting muscle
• storage and release site for calcium ions
• repeating unit of striated myofibrils
• thin filaments are anchored here

Answer 4

• storage and release site for calcium ions

Question 5

The repeating unit of a skeletal muscle fibre is the..

• sarcoplasmic reticulum.
• sarcolemma.
• myofibril.
• myofilament.
• sarcomere.

Answer 5

• sarcomere.

Question 6

After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as..

• rigor mortis.
• depolarization.
• treppe.
• tetany.
• oxygen debt.

Answer 6

• rigor mortis.

Question 7

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

• the striped appearance of skeletal muscle.
• muscle relaxation.
• the conduction of neural stimulation to the muscle fibre.
• muscle contraction.
• muscle fatigue.

Answer 7

• muscle contraction.

Question 8

Which of the following best describes the term Z line?

• thin filaments are anchored here
• protein that accounts for elasticity of resting muscle
• repeating unit of striated myofibrils
• storage site for calcium ions
• largely made of myosin molecules

Answer 8

• thin filaments are anchored here

Question 9

The type of contraction in which the muscle fibres do not shorten is called..

• isotonic.
• treppe.
• tetany.
• isometric.
• concentric.

Answer 9

• isometric.

Question 10

The action potential is conducted into a skeletal muscle fiber by..

• transverse tubules.
• motor end plates.
• sarcoplasmic reticulum.
• triads.
• neuromuscular junctions.

Answer 10

• transverse tubules.

Question 11

Each thin filament consists of..

• a double strand of myosin molecules.
• chains of myosin molecules.
• two protein strands coiled helically around each other.
• a rod-shaped structure with “heads” projecting from each end.
• six molecules coiled into a helical structure.

Answer 11

• two protein strands coiled helically around each other.

Question 12

When a muscle is stimulated repeatedly at a high rate, the amount of tension gradually increases to a steady maximum tension. This is called..

• a twitch.
• recruitment.
• wave summation.
• complete tetanus.
• incomplete tetanus.

Answer 12

• complete tetanus.

Question 13

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

• synaptic knob.
• sarcomere.
• transverse tubule.
• neuromuscular junction.
• synaptic cleft.

Answer 13

• neuromuscular junction.

Question 14

When calcium ion binds to troponin,

• tropomyosin moves into the groove between the helical actin strands.
• myosin shortens.
• active sites on the myosin are exposed.
• actin heads will bind to myosin.
• muscle relaxation occurs.

Answer 14

• tropomyosin moves into the groove between the helical actin strands.

Question 15

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

• acetylcholine.
• hydrogen ions.
• potassium ions.
• calcium ions.
• sodium ions.

Answer 15

• calcium ions.

Question 16

Which of the following best describes the term titin?

• repeating unit of striated myofibrils
• largely made of myosin molecules
• storage site for calcium ions
• thin filaments are anchored here
• protein that accounts for elasticity of resting muscle

Answer 16

• protein that accounts for elasticity of resting muscle

Question 17

Fast fibers…

• have low resistance to fatigue.
• rely on aerobic metabolism.
• have many mitochondria.
• have twitches with a very brief contraction phase.
• have low resistance to fatigue and have twitches with a very brief contraction phase.

Answer 17

• have low resistance to fatigue and have twitches with a very brief contraction phase.

Question 18

During anaerobic glycolysis..

• pyruvic acid is produced.
• oxygen is not consumed.
• ATP is produced.
• all of the above
• B and C only

Answer 18

• all of the above

Question 19

Which of the following statements is (are) true regarding human muscles?

• Eye muscles are composed entirely of fast fibers.
• Most have both slow and fast fibers.
• Slow fibers are abundant in the calf muscles.
• Slow fibers are abundant in the back muscles.
• All of the above.

Answer 19

• All of the above.

Question 20

1) Which of the following is a recognized function of skeletal muscle?
A) produce movement
B) maintain posture
C) maintain body temperature
D) guard body entrances and exits
E) All of the answers are correct.

Answer 20

E) All of the answers are correct.

Question 21

Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for

Answer 21

Contraction

Question 22

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

Answer 22

Epimysium

Question 23

Nerves and blood vessels that service the muscle fibers are located in the connective tissues of the

Answer 23

Perymysium

Question 24

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

Answer 24

Endomysium

Question 25

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

Answer 25

Tendon

Question 26

The advantage of having many nuclei in a skeletal muscle fiber is the ability to

Answer 26

The ability to produce large amounts of the enzymes and structural proteins needed for contraction.

Question 27

Skeletal muscle fibers are formed from embryonic cells called

Answer 27

Myoblasts

Question 28

At each end of the muscle, the collagen fibers of the epimysium, and each perimysium and endomysium, come together to form a

Answer 28

Tendon

Question 29

Individual muscle cells are surrounded by what connective tissue?

Answer 29

endomysium

Question 30

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

Answer 30

Myosatellite cells

Question 31

The plasma membrane of skeletal muscle is called the

Answer 31

Sacrolemma

Question 32

The region of the sarcomere containing the thick and thin filaments is the

Answer 32

A Band

Question 33

The region of the sarcomere that always contains only thin filaments is the

Answer 33

I Band

Question 34

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

Answer 34

H band

Question 35

The skeletal muscle complex known as the triad consists of

Answer 35

a transverse tubule and two terminal cisternae.

Question 36

receptors for acetylcholine are located on the

Answer 36

motor end plate

Question 37

the most important factor in decreasing the intracellular concentration of calcium ion after contraction is

Answer 37

active transport of calcium into the sarcoplasmic reticulum

Question 38

which of the following acts as an ATPase during the contraction cycle of muscle

Answer 38

the head portion of myosin molecule

Question 39

in rigor mortis..

Answer 39

ATP is depleted, the myosin heads are attached to actin, calcium ions keep binding to troponin, sustained contractions occur

Question 40

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

Answer 40

zone of overlap

Question 41

physical evidence that supports the sliding filament theory of muscle contraction includes

Answer 41

decreased width of H band during contraction

Question 42

triggering of the muscle action potential occurs after

Answer 42

acetylcholine binds to chemically gated channels in the motor end plate

Question 43

when acetylcholine binds to receptors at the motor end plate, the sarcolemma becomes

Answer 43

more permeable to sodium ions

Question 44

the rapid rise and fall in force produced by a muscle fiber after a single action potential is a

Answer 44

twitch

Question 45

when a muscle is stimulated repeatedly at a high rate, the amount of tension gradually increases to a steady maximum tension. this state of maximum tension is called

Answer 45

complete tetanus

Question 46

a muscle producing almost peak tension during rapid cycles of contraction and relaxation is said to be in

Answer 46

incomplete tetanus

Question 47

if a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This addition of one twitch to another is called

Answer 47

wave summation

Question 48

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

Answer 48

motor unit

Question 49

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

Answer 49

recruitment