ch 10 quiz

Question 1

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 1

b. lining hollow organs

Question 2

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

a. swimming laps
b. lifting weights
c. both A and B
d. neither A nor B

Answer 2

b. lifting weights

Question 3

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

a. Contraction would be prevented.
b. Contraction would be slowed.
c. The speed of contraction would increase.
d. The strength of contraction would increase.

Answer 3

a. Contraction would be prevented

Question 4

What statement(s) below are FALSE with regard to the contraction of skeletal muscle?

a. Through eccentric contractions, the muscle lengthens.
b. Through concentric contractions, the muscle does not change length.
c. Through isometric contraction, the muscle remains the same length.
d. A and C are correct.

Answer 4

b. Through concentric contractions, the muscle does not change length

Question 5

Which of the following describe the characteristics of slow muscle fibers?

a. small diameter, rich in myoglobin, and high glycogen reserve
b. large diameter, very vascular, and multiple mitochondria
c. small diameter, rich in myoglobin, and very vascular
d. large diameter, high glycogen reserve, and lack significant myoglobin

Answer 5

c. small diameter, rich in myoglobin, and very vascular

Question 6

How would severing the tendon attached to a muscle affect the muscle’s ability to move a body part?

a. Uncontrolled movement would result from a severed tendon.
b. Movement would be greatly exaggerated with no tendon.
c. No movement is possible without a muscle to bone connection.
d. Limited movement would result.

Answer 6

c. No movement is possible without a muscle to bone connection

Question 7

Which of the following describes the neuromuscular junction?

a. the surface containing membrane receptors that bind acetylcholine
b. special intercellular connection between axon branches and a skeletal muscle fiber
c. the link between generation of an action potential and the start of muscle contraction
d. a propagated change in membrane potential that travels the length of an axon

Answer 7

b. special intercellular connection between axon branches and a skeletal muscle fiber

Question 8

How are epimysium, perimysium, and endomysium interrelated?

a. They are connective tissues and blend with tendons to provide firm attachments to bone.
b. All three contain capillaries and nerves.
c. All three contain satellite cells that function in the repair of muscle tissue.
d. None of the above are correct

Answer 8

a. They are connective tissues and blend with tendons to provide firm attachments to bone.

Question 9

With excitation–contraction coupling,

a. a motor neuron releases ACh, which allows an electrical event to be transferred to the muscular system.
b. a motor neuron releases ACh, and it binds to receptors on the motor end plate of a muscle fascicle.
c. the myosin cross-bridge will remain attached to actin as ATP depletion occurs.
d. ACh release reveals actin’s binding site for myosin to bind

Answer 9

a. a motor neuron releases ACh, which allows an electrical event to be transferred to the muscular system.

Question 10

A motor unit is/are _____. You would need a small motor unit to control movement of the fingers _____.

a. the resting tension in a muscle; so it would not involve muscle fibers of adjoining fingers
b. muscle fibers controlled by a single motor neuron; because you need precise control
c. the addition of one twitch to another; because you need twitches to cover a large area
d. None of the above are correct.

Answer 10

b. muscle fibers controlled by a single motor neuron; because you need precise control

Question 11

Myofibrils are organized into repeating subunits called _____.

a. T tubules
b. Z lines
c. sarcomeres
d. sarcoplasmic reticulum

Answer 11

c. sarcomeres

Question 12

Why does skeletal muscle appear striated when viewed through a microscope?

a. Z lines and myosin filaments align within a muscle fiber.
b. Glycogen reserves are linearly arranged.
c. Capillaries regularly intersect the myofibers.
d. Actin filaments repel stain, appearing banded.

Answer 12

a. Z lines and myosin filaments align within a muscle fiber.

Question 13

The A band comprises which of the following subunits?

a. I band, terminal cisternae, and the Z line
b. M line, H band, and the zone of overlap
c. thin filaments, titin, and the Z line
d. sarcoplasmic reticulum, and T tubules

Answer 13

b. M line, H band, and the zone of overlap

Question 14

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

a. in T tubules
b. surrounding the mitochondria
c. within sarcomeres
d. in cisternae of the sarcoplasmic reticulum

Answer 14

d. in cisternae of the sarcoplasmic reticulum

Question 15

In what ways does the appearance of a sarcomere change during contraction of a skeletal muscle fiber?

a. zones of overlap get larger; H band gets wider; A bands shorten
b. titin molecules are relaxed; M line disappears
c. Z lines move closer together; I bands and H bands get smaller
d. None of the above are correct.

Answer 15

c. Z lines move closer together; I bands and H bands get smaller

Question 16

_____ predominate in the large leg muscles of someone who excels at endurance activities, such as cycling. This is because _____.

a. Fast fibers; they have large glycogen reserves
b. Slow fibers; they have extensive capillary networks and much myoglobin
c. Nonvascular fibers; they use both aerobic and anaerobic metabolism
d. Intermediate fibers; they have more neuromuscular junctions

Answer 16

b. Slow fibers; they have extensive capillary networks and much myoglobin

Question 17

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

a. the reaction between ADP and creatine
b. aerobic metabolism in mitochondria
c. glycolysis in the cytoplasm
d. both B and C

Answer 17

c. glycolysis in the cytoplasm

Question 18

Why does a muscle that has been overstretched produce less tension?

a. Few cross-bridges form, causing weak contraction.
b. Cross-bridges cannot be formed.
c. Actin and myosin cease to be stimulated by acetylcholine.
d. The increased amount of Ca2+ in the sarcoplasm causes the muscle to relax completely.

Answer 18

a. Few cross-bridges form, causing weak contraction.

Question 19

What would you expect to happen to a resting skeletal muscle if the sarcolemma suddenly became very permeable to Ca2+?

a. increased strength of contraction
b. decreased cross-bridge
c. decreased ability to relax
d. both A and C

Answer 19

d. both A and C

Question 20

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

a. Muscle would lose strength.
b. Muscle would be unable to contract.
c. Acetylcholine receptors would be inactivated in the motor end plate.
d. Muscle would contract repeatedly

Answer 20

d. Muscle would contract repeatedly

Question 21

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

a. striations
b. desmosomes
c. gap junctions
d. short T tubules without triads

Answer 21

c. gap junctions

Question 22

Smooth muscle can contract over a wider range of resting lengths than skeletal muscle can. Why?

a. Smooth muscle sarcomeres are longer.
b. Actin and myosin filament arrangement is less organized in smooth muscle.
c. Smooth muscle cells are shorter.
d. Smooth muscle actin is longer.

Answer 22

b. Actin and myosin filament arrangement is less organized in smooth muscle

Question 23

What structural characteristics distinguish cardiac muscle tissue from skeletal muscle tissue? Cardiac muscle cells _____.

a. are larger and usually have one nucleus
b. have intercalated discs, short T tubules, and no triads
c. are dependent on anaerobic metabolism
d. contact each other at tight junctions

Answer 23

b. have intercalated discs, short T tubules, and no triads

Question 24

Two cardiologists are talking about functional characteristics of cardiac muscle tissue. Which of the following descriptions would they use?

a. special gap junctions, intrinsic conduction system allows contraction without neural stimulation
b. spindle-shaped, nonstriated, thick filaments scattered, involuntary
c. striated tissue with multiple mitochondria and a multinucleated condition syncytium
d. Cardiologists would not use any of this terminology.

Answer 24

a. special gap junctions, intrinsic conduction system allows contraction without neural stimulation

Question 25

Why are cardiac and smooth muscle contractions more affected by changes in extracellular Ca2+ than skeletal muscle contractions?

a. Extracellular Ca2+ inhibits actin.
b. Cross-bridges are formed only within the sarcomeres of cardiac muscle.
c. Most of the calcium for contractions comes from SR stores.
d. Most of the calcium for contractions comes from extracellular fluid

Answer 25

d. Most of the calcium for contractions comes from extracellular fluid.

Question 26

Why would a sprinter experience muscle fatigue before a marathon runner?

a. Marathon running uses ATP for only a short time, while sprinting uses ATP indefinitely.
b. Marathon runners’ muscles depend on stored glycogen; therefore, they do not fatigue.
c. Sprinting involves anaerobic endurance, whereas running a marathon depends more upon availability of substrates for aerobic respiration.
d. None of the above are correct.

Answer 26

c. Sprinting involves anaerobic endurance, whereas running a marathon depends more upon availability of substrates for aerobic respiration.