Question 1

A myofilament 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 or myosin.F) None of the above
G) A) and E)

Question 2

Synaptic vesicles in the neuromuscular junction contain

Accepted Answer

A)   calcium.
B)   ATP.
C)   acetylcholine.
D)   acetylcholinesterase.
E)   sodium.F) None of the above
G) All of the above

Question 3

What is a cross-bridge?

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) None of the above
G) B) and D)

Question 4

Myosin phosphatase

Accepted Answer

A)   activates myosin kinase.
B)   forms the cross-bridge.
C)   removes phosphate from myosin.
D)   binds to calcium-calmodulin complex.
E)   opens calcium channels.F) A) and E)
G) C) and E)

Question 5

Which type of muscle tissue is autorhythmic?

Accepted Answer

A)   skeletal muscle
B)   smooth muscle
C)   cardiac muscle
D)   both skeletal and cardiac muscle
E)   both cardiac and smooth muscleF) C) and D)
G) A) and E)

Question 6

Heather is watching a movie. What type of chemical pathway do her muscles depend upon at this time?

Accepted Answer

A)   anaerobic respiration
B)   aerobic respiration
C)   both anaerobic and aerobic respirationD) A) and C)
E) B) and C)

Question 7

When an action potential reaches the presynaptic terminal,

Accepted Answer

A)   calcium ions diffuse into the presynaptic terminal through voltage-gated ion channels.
B)   acetylcholine moves into the presynaptic terminal.
C)   a local potential is generated in the presynaptic terminal.
D)   ligand-gated ion channels in the presynaptic terminal are opened.
E)   nothing else happens.F) A) and D)
G) D) and E)

Question 8

Myosin is also known as the

Accepted Answer

A)   thick myofilament.
B)   thin myofilament.
C)   intermediate myofilament.
D)   short myofilament.
E)   sarcomere.F) B) and E)
G) A) and E)

Question 9

The electrical properties of cells are the result of

Accepted Answer

A)   ion concentration differences across the plasma membrane.
B)   receptor sites that are present on the plasma membrane.
C)   phosphorylation reactions within the cytoplasm.
D)   phospholipids in the cell membrane.
E)   None of these choices is correct.F) A) and B)
G) A) and C)

Question 10

Arrange the following list of biochemical events in the correct sequence. (1)  An action potential is conducted deep into the muscle fiber by the T tubule.
(2)  Calcium ions bind to troponin.
(3)  The membranes of the sarcoplasmic reticulum become more permeable to calcium ions.
(4)  Calcium ions diffuse into the sarcoplasm around the myofibril.
(5)  The troponin-tropomyosin complex moves exposing active sites.

Accepted Answer

A)   1, 5, 2, 3, 4
B)   1, 3, 4, 2, 5
C)   1, 2, 3, 4, 5
D)   1, 3, 2, 5, 4
E)   1, 4, 3, 2, 5F) C) and E)
G) D) and E)

Question 11

Treppe

Accepted Answer

A)   can contribute to improved muscle efficiency.
B)   may be due to an increase in the level of calcium ions around the myofibril.
C)   is an example of a graded response.
D)   is achieved during warm-up exercises.
E)   All of these choices are correct.F) A) and E)
G) B) and E)

Question 12

Consider a chemical that blocks the action of acetylcholinesterase. What effect does this have on muscles?

Accepted Answer

A)   It would cause paralysis.
B)   It would cause action potentials to be inhibited, thereby rendering the muscle useless.
C)   The body would increase it's production of acetylcholine to compensate.
D)   The axons of the motor neurons would atrophy and the muscle would weaken.
E)   The muscle would have no way to relax, and spastic contractions would result.F) A) and E)
G) All of the above

Question 13

The diffusion of calcium ions into a smooth muscle cell does not depolarize the membrane so no action potential occurs.

Accepted Answer

A) True 
 B)False

Question 14

-The figure illustrates a detailed drawing of the neuromuscular junction. What does "C" represent?

Accepted Answer

A)   synaptic vesicles
B)   synaptic cleft
C)   sarcolemma
D)   presynaptic terminal
E)   postsynaptic membraneF) A) and D)
G) B) and C)

Question 15

You are hired to work in a laboratory to measure the rate of human muscle contraction. Which of the following might decrease in quantity in muscle cells undergoing contractions?

Accepted Answer

A)   ATP
B)   carbon dioxide
C)   water
D)   lactic acid
E)   sodiumF) A) and C)
G) C) and D)

Question 16

Skeletal muscle develops from multinucleated cells called

Accepted Answer

A)   fascicles.
B)   myoblasts.
C)   myofibrils.
D)   myotomes.
E)   fasciculi.F) A) and B)
G) A) and C)

Question 17

Which of the following would contribute to muscular fatigue in the muscle fiber?

Accepted Answer

A)   the emotional state of an individual
B)   depletion of ATP reserves
C)   inability of the motor neuron to produce sufficient quantities of acetylcholine
D)   depletion of neurotransmitter
E)   blocked receptors in the postsynaptic membraneF) A) and E)
G) A) and B)

Question 18

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) B) and D)

Question 19

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) C) and E)

Question 20

An isotonic 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 C)
G) A) and E)

Exam 9: Muscular System: Histology and Physiology

Myosin phosphatase

Correct Answer
verified

Synaptic vesicles in the neuromuscular junction contain

Correct Answer
verified

Which of the following would contribute to muscular fatigue in the muscle fiber?

Correct Answer
verified

Correct Answer
verified

Muscle myofibrils

Correct Answer
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The diffusion of calcium ions into a smooth muscle cell does not depolarize the membrane so no action potential occurs.

Correct Answer
verified

-The figure illustrates a detailed drawing of the neuromuscular junction. What does "C" represent?

Correct Answer
verified

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

Correct Answer
verified

What is a cross-bridge?

Correct Answer
verified

Myosin is also known as the

Correct Answer
verified

Heather is watching a movie. What type of chemical pathway do her muscles depend upon at this time?

Correct Answer
verified

A myofilament is the

Correct Answer
verified

When an action potential reaches the presynaptic terminal,

Correct Answer
verified

Treppe

Correct Answer
verified

An isotonic contraction is described as

Correct Answer
verified

Skeletal muscle develops from multinucleated cells called

Correct Answer
verified

Consider a chemical that blocks the action of acetylcholinesterase. What effect does this have on muscles?

Correct Answer
verified

Which type of muscle tissue is autorhythmic?

Correct Answer
verified

You are hired to work in a laboratory to measure the rate of human muscle contraction. Which of the following might decrease in quantity in muscle cells undergoing contractions?

Correct Answer
verified

The electrical properties of cells are the result of

Correct Answer
verified

Exam 9: Muscular System: Histology and Physiology

Myosin phosphatase

Correct AnswerverifiedShow Answer

Synaptic vesicles in the neuromuscular junction contain

Correct AnswerverifiedShow Answer

Which of the following would contribute to muscular fatigue in the muscle fiber?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Muscle myofibrils

Correct AnswerverifiedShow Answer

The diffusion of calcium ions into a smooth muscle cell does not depolarize the membrane so no action potential occurs.

Correct AnswerverifiedShow Answer

-The figure illustrates a detailed drawing of the neuromuscular junction. What does "C" represent?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

What is a cross-bridge?

Correct AnswerverifiedShow Answer

Myosin is also known as the

Correct AnswerverifiedShow Answer

Heather is watching a movie. What type of chemical pathway do her muscles depend upon at this time?

Correct AnswerverifiedShow Answer

A myofilament is the

Correct AnswerverifiedShow Answer

When an action potential reaches the presynaptic terminal,

Correct AnswerverifiedShow Answer

Treppe

Correct AnswerverifiedShow Answer

An isotonic contraction is described as

Correct AnswerverifiedShow Answer

Skeletal muscle develops from multinucleated cells called

Correct AnswerverifiedShow Answer

Consider a chemical that blocks the action of acetylcholinesterase. What effect does this have on muscles?

Correct AnswerverifiedShow Answer

Which type of muscle tissue is autorhythmic?

Correct AnswerverifiedShow Answer

You are hired to work in a laboratory to measure the rate of human muscle contraction. Which of the following might decrease in quantity in muscle cells undergoing contractions?

Correct AnswerverifiedShow Answer

The electrical properties of cells are the result of

Correct AnswerverifiedShow Answer

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