Question 1

Identify the statement concerning general functional characteristics of muscle that is true.

Accepted Answer

A)  Muscle tissue shortens forcefully but lengthens passively. 
B)  Muscle tissue shortens passively but lengthens forcefully. 
C)  Muscle tissue can get shorter, but can not get longer. 
D)  Muscle tissue can get longer, but can not get shorter. 
E)  None of these statements are true. 
A)  Muscle tissue shortens forcefully but lengthens passively. 
B)  Muscle tissue shortens passively but lengthens forcefully. 
C)  Muscle tissue can get shorter, but can not get longer. 
D)  Muscle tissue can get longer, but can not get shorter. 
E)  None of these statements are true.

Question 2

A muscle fiber will respond to a stimulus when that stimulus reaches the _____ level.

Accepted Answer

A)  threshold 
B)  relaxation 
C)  rigor mortis 
D)  recruitment 
E)  resting 
A)  threshold 
B)  relaxation 
C)  rigor mortis 
D)  recruitment 
E)  resting

Question 3

Which of the following statements concerning smooth muscle is true?

Accepted Answer

A)  It contains many sarcomeres. 
B)  Caveolae seem to take the place of the myofibrils. 
C)  A calcium-calmodulin complex initiates cross-bridge formation. 
D)  The cells are large and multinuclear. 
E)  It has a well developed sarcoplasmic reticulum. 
A)  It contains many sarcomeres. 
B)  Caveolae seem to take the place of the myofibrils. 
C)  A calcium-calmodulin complex initiates cross-bridge formation. 
D)  The cells are large and multinuclear. 
E)  It has a well developed sarcoplasmic reticulum.

Question 4

Skeletal muscle fibers

Accepted Answer

A)  possess striations. 
B)  can contract but are not extensible or excitable. 
C)  do not require nerve innervation to contract. 
D)  increase dramatically in number after birth. 
E)  are found in the walls of the stomach. 
A)  possess striations. 
B)  can contract but are not extensible or excitable. 
C)  do not require nerve innervation to contract. 
D)  increase dramatically in number after birth. 
E)  are found in the walls of the stomach.

Question 5

Which of the following would occur as a result of a single muscle contraction?

Accepted Answer

A)  tetanus 
B)  tone 
C)  treppe 
D)  twitch 
E)  paralysis 
A)  tetanus 
B)  tone 
C)  treppe 
D)  twitch 
E)  paralysis

Question 6

In smooth muscle, cross-bridging occurs due to

Accepted Answer

A)  calcium binding to troponin. 
B)  calcium binding to calmodulin. 
C)  myosin kinase adding a phosphate to myosin heads. 
D)  both calcium binding to troponin and calmodulin. 
E)  both calcium binding to calmodulin and myosin kinase adding a phosphate to myosin heads. 
A)  calcium binding to troponin. 
B)  calcium binding to calmodulin. 
C)  myosin kinase adding a phosphate to myosin heads. 
D)  both calcium binding to troponin and calmodulin. 
E)  both calcium binding to calmodulin and myosin kinase adding a phosphate to myosin heads.

Question 7

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. 
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.

Question 8

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. 
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.

Question 9

What is tropomyosin?

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 metabolism 
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 metabolism

Question 10

Which of the following will respond to a threshold stimulus with an all-or-none contraction?

Accepted Answer

A)  a single muscle fiber 
B)  a single motor unit 
C)  a whole muscle 
D)  a single muscle fiber and a single motor unit 
E)  a single muscle fiber, a single motor unit, and a whole muscle 
A)  a single muscle fiber 
B)  a single motor unit 
C)  a whole muscle 
D)  a single muscle fiber and a single motor unit 
E)  a single muscle fiber, a single motor unit, and a whole muscle

Question 11

Muscle atrophy

Accepted Answer

A)  involves an increase in the number of muscle fibers. 
B)  is characterized by a decrease in muscle size. 
C)  results from aerobic exercise. 
D)  causes an increase in blood flow to the affected muscle. 
E)  is characterized by an increase in muscle size. 
A)  involves an increase in the number of muscle fibers. 
B)  is characterized by a decrease in muscle size. 
C)  results from aerobic exercise. 
D)  causes an increase in blood flow to the affected muscle. 
E)  is characterized by an increase in muscle size.

Question 12

-What does "B" represent on the diagram?

Accepted Answer

A)  myosin myofilament 
B)  actin myofilament 
C)  sarcomere 
D)  Z disk 
E)  cross-bridge 
A)  myosin myofilament 
B)  actin myofilament 
C)  sarcomere 
D)  Z disk 
E)  cross-bridge

Question 13

-What does "B" represent on the diagram?

Accepted Answer

A)  threshold 
B)  depolarization 
C)  depolarization phase of action potential 
D)  repolarization phase of action potential 
A)  threshold 
B)  depolarization 
C)  depolarization phase of action potential 
D)  repolarization phase of action potential

Question 14

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. 
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.

Question 15

Which of the following events occurs during the lag phase of a muscle twitch?

Accepted Answer

A)  Muscle fibers shorten. 
B)  Cross-bridges form, move, release, and reform many times. 
C)  The action potential is propagated from presynaptic to postsynaptic membrane. 
D)  Calcium is pumped back into the sarcoplasmic reticulum. 
E)  All of these events occur in the lag phase. 
A)  Muscle fibers shorten. 
B)  Cross-bridges form, move, release, and reform many times. 
C)  The action potential is propagated from presynaptic to postsynaptic membrane. 
D)  Calcium is pumped back into the sarcoplasmic reticulum. 
E)  All of these events occur in the lag phase.

Question 16

If sodium ions cannot enter a muscle fiber in response to a stimulus,

Accepted Answer

A)  contraction cannot occur. 
B)  relaxation cannot occur. 
C)  sodium ions will be released from the sarcoplasmic reticulum instead. 
D)  the active sites are left exposed. 
E)  the action potential travels into the muscle anyway. 
A)  contraction cannot occur. 
B)  relaxation cannot occur. 
C)  sodium ions will be released from the sarcoplasmic reticulum instead. 
D)  the active sites are left exposed. 
E)  the action potential travels into the muscle anyway.

Question 17

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 ions 
A)  acetylcholine production 
B)  rapid degradation of acetylcholine 
C)  release of neurotransmitter 
D)  neurotransmitter combines with a receptor molecule 
E)  release of calcium ions

Question 18

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

Question 19

Which of the following situations occurs in electrically excitable cells?

Accepted Answer

A)  When Na+ ion channels open, K+ ion channels close. 
B)  The sodium-potassium pump moves sodium into the cell. 
C)  Depolarization causes voltage-gated sodium ion channels to open. 
D)  Sodium ion channels are opened by high extracellular calcium levels. 
E)  The opening and closing of ligand-gated channels cause depolarization. 
A)  When Na+ ion channels open, K+ ion channels close. 
B)  The sodium-potassium pump moves sodium into the cell. 
C)  Depolarization causes voltage-gated sodium ion channels to open. 
D)  Sodium ion channels are opened by high extracellular calcium levels. 
E)  The opening and closing of ligand-gated channels cause depolarization.

Question 20

In excitation-contraction coupling,

Accepted Answer

A)  calcium ions must bind with myosin to expose active sites on actin. 
B)  myosin heads bind to exposed active sites on actin. 
C)  cross-bridges form between myosin heads and calcium ions. 
D)  movement of the troponin-tropomyosin complex causes actin myofilaments to slide. 
E)  ATP binds to actin myofilaments. 
A)  calcium ions must bind with myosin to expose active sites on actin. 
B)  myosin heads bind to exposed active sites on actin. 
C)  cross-bridges form between myosin heads and calcium ions. 
D)  movement of the troponin-tropomyosin complex causes actin myofilaments to slide. 
E)  ATP binds to actin myofilaments.

Exam 9: Muscular System: Histology and Physiology

Identify the statement concerning general functional characteristics of muscle that is true.

A muscle fiber will respond to a stimulus when that stimulus reaches the _____ level.

Which of the following statements concerning smooth muscle is true?

Skeletal muscle fibers

Which of the following would occur as a result of a single muscle contraction?

In smooth muscle, cross-bridging occurs due to

During the contraction phase of a muscle twitch,

A myofibril is the

What is tropomyosin?

Which of the following will respond to a threshold stimulus with an all-or-none contraction?

Muscle atrophy

-What does "B" represent on the diagram?

-What does "B" represent on the diagram?

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

Which of the following events occurs during the lag phase of a muscle twitch?

If sodium ions cannot enter a muscle fiber in response to a stimulus,

Which of the following events occurs on the postsynaptic membrane?

Myosin phosphatase

Which of the following situations occurs in electrically excitable cells?

In excitation-contraction coupling,

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