Question 1

A myofibril is the

Accepted Answer

A)  cell membrane of a muscle fiber.
B)  cytoplasm of muscle cells.
C)  structural and functional unit of the skeletal muscle cell.
D)  contractile thread that extends the length of the muscle fiber.
E)  protein strand composed of actin.F) A) and D)
G) D) and E)

Question 2

Which of the following structures contains the other four items listed?

Accepted Answer

A)  postsynaptic membrane
B)  presynaptic terminal
C)  synaptic cleft
D)  neuromuscular junction
E)  receptors on postsynaptic membraneF) A) and B)
G) A) and C)

Question 3

Muscle tone

Accepted Answer

A)  is a time during which the tissue cannot respond again.
B)  results in complete and incomplete tetanus.
C)  is a condition in which the muscle fiber only partially relaxes between contractions.
D)  is a condition in which stimuli occur so rapidly that there are no intervening relaxations.
E)  is a constant tension produced by muscles for long periods of time.F) A) and D)
G) C) and E)

Question 4

Complete tetanus

Accepted Answer

A)  is the time during which the tissue cannot respond again.
B)  results in complete and incomplete tetanus.
C)  is the condition in which the muscle fiber only partially relaxes between contractions.
D)  is the condition in which stimuli occur so rapidly that there are no intervening relaxations.
E)  is the constant tension produced by muscles for long periods of time.F) A) and D)
G) A) and B)

Question 5

The active sites to which cross-bridges attach are found on the

Accepted Answer

A)  sarcoplasmic reticulum.
B)  actin myofilaments.
C)  Z disks.
D)  T tubules.
E)  myosin myofilaments.F) B) and E)
G) All of the above

Question 6

Consider the following four phrases and select the one that does not belong with the others.

Accepted Answer

A)  anaerobic metabolism
B)  lactic acid production
C)  fast twitch fibers
D)  fuels runner in a marathon
E)  muscle fibers split ATP rapidlyF) A) and D)
G) A) and B)

Question 7

Which of the following actions is caused by contraction of skeletal muscle?

Accepted Answer

A)  contraction of the heart
B)  moving your feet in walking
C)  movement of food through the digestive tract
D)  emptying of the urinary bladder
E)  vasoconstrictionF) B) and E)
G) A) and D)

Question 8

Muscle myofibrils

Accepted Answer

A)  are found in the sarcolemma.
B)  extend from the sarcolemma to the T-tubule.
C)  contain myosin and actin myofilaments.
D)  hold muscle cells together.
E)  do not appear striated.F) C) and E)
G) A) and E)

Question 9

Which of the following connective tissue layers is outside all the others?

Accepted Answer

A)  perimysium
B)  endomysium
C)  epimysium
D)  paramysium
E)  sarcolemmaF) All of the above
G) C) and D)

Question 10

Which of the following events occurs on the postsynaptic membrane?

Accepted Answer

A)  acetylcholine production
B)  rapid degradation of acetylcholine
C)  release of neurotransmitter
D)  neurotransmitter combines with a receptor molecule
E)  release of calcium ionsF) All of the above
G) A) and C)

Question 11

Which type of muscle tissue would cause flexion and extension of the arm?

Accepted Answer

A)  skeletal muscle
B)  smooth muscle
C)  cardiac muscleD) A) and C)
E) B) and C)

Question 12

Acetylcholine is released from the presynaptic terminal by the process of

Accepted Answer

A)  exocytosis.
B)  diffusion.
C)  phagocytosis.
D)  active transport.
E)  endocytosis.F) A) and B)
G) A) and C)

Question 13

An eccentric contraction is described as

Accepted Answer

A)  action potential frequency is high enough that no relaxation of muscle fibers occurs.
B)  a muscle produces constant tension during contraction.
C)  a muscle produces an increasing tension during contraction.
D)  a muscle produces increasing tension as it shortens.
E)  a muscle produces tension,but the length of the muscle is increasing.F) B) and E)
G) B) and D)

Question 14

What is the power stroke?

Accepted Answer

A)  a protein found along the groove of the F-actin double helix
B)  a T tubule and two adjacent terminal cisternae
C)  the combination of myosin heads with active sites on actin molecules
D)  the movement of myosin head while attached to actin myofilament
E)  after exercise,the oxygen taken in that exceeds the oxygen required for resting metabolismF) B) and E)
G) A) and B)

Question 15

Aerobic respiration

Accepted Answer

A)  produces ATP molecules faster than anaerobic respiration.
B)  yields as many as 36 ATP per glucose molecule metabolized.
C)  occurs whether oxygen is present or not.
D)  occurs entirely in the cytoplasm.
E)  occurs in the ribosomes.F) B) and D)
G) A) and B)

Question 16

During the contraction phase of a muscle twitch,

Accepted Answer

A)  acetylcholine stimulates the pre-synaptic terminal.
B)  sodium ions diffuse into the muscle fiber.
C)  actin-myosin cross-bridges form.
D)  calcium ions are transported back to the sarcoplasmic reticulum.
E)  the action potential travels down the T tubule.F) B) and E)
G) All of the above

Question 17

A child ingested an organophosphate poison used to kill insects.Soon the child's muscles began spastic contractions.Predict what occurred at the synaptic cleft.

Accepted Answer

A)  decreased release of acetylcholine from presynaptic neurons
B)  increased accumulation of acetylcholine in the synapse
C)  the poison binds to acetylcholine receptors and stimulates them
D)  increased breakdown of acetylcholine in the synaptic cleft
E)  Both increased accumulation of acetylcholine in the synapse and increased breakdown of acetylcholine in the synaptic cleft.F) D) and E)
G) B) and E)

Question 18

Which of the following statements concerning types of muscle contractions is false?

Accepted Answer

A)  In isometric contractions,the amount of tension produced by the muscle is constant.
B)  In isotonic contractions,the muscle fibers shorten.
C)  The contractile processes in isometric and isotonic contractions are the same.
D)  Most skeletal muscle contractions are a combination of isometric and isotonic contractions.
E)  In isotonic contractions,the amount of tension produced by the muscle fibers is constant during the contraction.F) A) and B)
G) None of the above

Question 19

What are caveolae?

Accepted Answer

A)  can rapidly develop action potentials
B)  shallow invaginations of cell membrane
C)  relatively constant tension maintained for a period of time
D)  intracellular cytoskeleton
E)  enzyme that removes phosphate from myosinF) B) and E)
G) B) and C)

Question 20

Movements of the body are usually smooth and occur at differing rates because

Accepted Answer

A)  they are a mixture of isotonic and isometric contractions.
B)  motor units contract out of phase at their own particular rates.
C)  most muscle contractions closely resemble individual muscle twitches.
D)  muscles of different sizes contract at different rates.
E)  of the all or none principle.F) A) and E)
G) D) and E)

Exam 9: Muscular System: Histology and Physiology

Which of the following actions is caused by contraction of skeletal muscle?

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The active sites to which cross-bridges attach are found on the

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Movements of the body are usually smooth and occur at differing rates because

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Consider the following four phrases and select the one that does not belong with the others.

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During the contraction phase of a muscle twitch,

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An eccentric contraction is described as

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Muscle myofibrils

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Which of the following connective tissue layers is outside all the others?

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Aerobic respiration

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What are caveolae?

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Which of the following structures contains the other four items listed?

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A child ingested an organophosphate poison used to kill insects.Soon the child's muscles began spastic contractions.Predict what occurred at the synaptic cleft.

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Acetylcholine is released from the presynaptic terminal by the process of

Correct AnswerverifiedShow Answer

Which of the following statements concerning types of muscle contractions is false?

Correct AnswerverifiedShow Answer

Complete tetanus

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A myofibril is the

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Which type of muscle tissue would cause flexion and extension of the arm?

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What is the power stroke?

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Which of the following events occurs on the postsynaptic membrane?

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Muscle tone

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