Question 1

Which is a TRUE statement about excitation-contraction coupling?

Accepted Answer

A)  In skeletal muscle cells,it requires the influx of extracellular calcium ion.
B)  In smooth muscle cells,it must be preceded by an action potential in the cell membrane.
C)  In all kinds of muscle it requires the entry of calcium from the extracellular fluid.
D)  Calcium-induced calcium release plays a role in cardiac muscle cells,as well as in some smooth muscle cells.
E)  In skeletal muscle cells,excitation-contraction coupling begins when an action potential propagates along the sarcoplasmic reticulum membrane.F) C) and D)
G) A) and B)

Question 2

Which of the following properties of smooth muscle helps us to understand why,as pregnancy advances,women get more and more Braxton-Hicks (smooth muscle) contractions in the uterine wall?

Accepted Answer

A)  Smooth muscle cells contract in response to stretch.
B)  Smooth muscle cells contract in response to NO.
C)  Smooth muscle cells contract in response to CO₂.
D)  Smooth muscle cells contract in response to changes in pH.E) A) and B)
F) None of the above

Question 3

Which of the following statements regarding myosin in skeletal muscle is TRUE?

Accepted Answer

A)  Myosin cross-bridge heads contain two binding sites,one for actin and one for tropomyosin.
B)  Myosin is an ATPase.
C)  The rate of ATP hydrolysis by myosin is the same in all types of skeletal muscle.
D)  All of the myosin cross-bridge heads in a thick filament are oriented and rotate in the same direction.
E)  Troponin covers the binding site on myosin molecules until Ca²⁺ binds to troponin to remove it from its blocking position.F) A) and C)
G) A) and E)

Question 4

Why does breathing continue to be rapid and deep for a time after heavy exercise?

Accepted Answer

A)  Extra oxygen is needed to restore muscle creatine phosphate concentration.
B)  The respiratory system is slow to increase and decrease its function before and after exercise,which is why it takes awhile for breathing to slow down.
C)  Lactic acid that builds up during heavy exercise must be exhaled into the air,so heavy breathing must continue for awhile after exercise to eliminate it.
D)  The ATP level in muscle cells falls drastically during heavy exercise,and extra oxygen is needed to restore it.
E)  The extra ventilation is not needed to replenish energy stores in muscle fibers,but rather simply to restore the blood pH to normal after the production of excess lactic acid during the exercise.F) B) and E)
G) A) and E)

Question 5

If you took a drug that acts as an inhibitor of creatine kinase,you would still be able to contract your muscles,but in order to sustain a contraction you may notice an increase in ventilatory and heart rates.

Accepted Answer

A) True 
 B)False

Question 6

Which best describes a "myofibril"?

Accepted Answer

A)  It is a single skeletal muscle cell.
B)  It is a cylindrical cellular organelle composed of myofilaments.
C)  It is a hollow membranous structure that stores calcium.
D)  It is composed of a single type of protein and forms cross-bridges.
E)  It is a fibrous junction between a muscle cell and a tendon.F) None of the above
G) All of the above

Question 7

Skeletal muscles are made up of bundles of muscle fibers attached to bone by connective tissue called tendons.

Accepted Answer

A) True 
 B)False

Question 8

If a biopsy of the quadriceps muscles (muscles on the front of the thigh) were taken from gold medal-winning speed skaters in the four following events,which would most likely have the SMALLEST percentage of type 1 muscle fibers?

Accepted Answer

A)  10,000 meters
B)  5,000 meters
C)  1,000 meters
D)  500 metersE) C) and D)
F) A) and B)

Question 9

Which of the following statements regarding contraction of a skeletal muscle fiber is TRUE?

Accepted Answer

A)  Thick filaments shorten when muscle cells contract.
B)  Some contractions occur without cross-bridge activation.
C)  Contracting muscle fibers do not always shorten.
D)  Contraction does not always require the occurrence of an action potential.
E)  Contraction only occurs following summation of action potentials from many motor neurons.F) C) and D)
G) A) and B)

Question 10

Which is a TRUE statement about smooth muscle?

Accepted Answer

A)  Smooth muscle is striated.
B)  Smooth muscle does not have thick and thin filaments.
C)  Smooth muscle does not use troponin-tropomyosin to regulate cross-bridge activity.
D)  Changes in cytosolic calcium do not regulate cross-bridge activity in smooth muscle.
E)  The myosin in smooth muscle requires phosphorylation before it can bind to ATP.F) A) and E)
G) C) and D)

Question 11

During isometric contraction of a skeletal muscle fiber,tension increases but the fiber length stays the same.

Accepted Answer

A) True 
 B)False

Question 12

Which of the following statements regarding contraction in skeletal and smooth muscle is TRUE?

Accepted Answer

A)  In skeletal muscle,calcium initiates contraction by binding to troponin,while in smooth muscle calcium initiates contraction by binding directly to myosin.
B)  In skeletal muscle,calcium ions bind to a regulatory protein on thin filaments;in smooth muscle,calcium ions bind to a regulatory protein on thick filaments.
C)  In skeletal muscle,calcium initiates contraction by binding to myosin light-chain kinase,while in smooth muscle calcium initiates contraction by binding directly to tropomyosin.
D)  In skeletal muscle,calcium initiates contraction by binding to troponin,while in smooth muscle calcium initiates contraction by binding to calmodulin.
E)  All of the choices are true.F) A) and D)
G) B) and E)

Question 13

Tetanus toxin inhibits acetylcholinesterase activity.What will a person suffering from tetanus toxin poisoning look like?

Accepted Answer

A)   All muscles of the body might exhibit frequent small twitches.
B)  All muscles of the body might present a tense,fully contracted state.
C)  All muscles of the body might present a limp,relaxed state known as flaccid paralysis.
D)  All muscles of the body will be completely normal in function.E) None of the above
F) A) and B)

Question 14

Based on its molecular properties,nicotine will have what effect on skeletal muscle contraction?

Accepted Answer

A)  Increases in contraction or contraction is more likely to happen
B)  Decreases in contraction or contraction is less likely to happen
C)  Effects on the motor neuron,but not on the muscle tissue itself
D)  Nicotine has no effect on muscle cellsE) A) and B)
F) B) and D)

Question 15

Compared to type 1,both forms of type 2 muscle fibers usually have a large diameter.

Accepted Answer

A) True 
 B)False

Question 16

The decrease in mass and strength of muscle as a result of damage to the nerves innervating the muscle is called disuse atrophy.

Accepted Answer

A) True 
 B)False

Question 17

Multiunit smooth muscle cells

Accepted Answer

A)  generally have individual innervation of each cell.
B)  have many gap junctions between cells.
C)  respond to stretch by relaxing.
D)  can only be excited,and not inhibited.
E)  have abundant T-tubules.F) C) and D)
G) B) and D)

Question 18

Sarah is a girl with dreams of becoming an Olympic marathon runner.She just learned that she has a rare genetic mutation and does not produce functional creatine phosphate.What portion of Sarah's marathon experience will be effected?

Accepted Answer

A)  Just the first few seconds of exercise
B)  All muscle contractions after Sarah reaches her maximum heart rate (about 10 minutes into her run) 
C)  All muscle contractions after Sarah reaches fatigue (about an hour into her run) 
D)  Every moment of Sarah's runs
E)  No effects on her runningF) C) and D)
G) A) and E)

Question 19

In the first few seconds of skeletal muscle contraction,what is the main mechanism by which ATP is replenished?

Accepted Answer

A)  Energy and phosphate are transferred from creatine phosphate to ADP.
B)  Oxidative phosphorylation rapidly generates ATP from glucose.
C)  Glycolysis produces ATP from glycogen.
D)  Oxidation of fatty acids into ATP occurs in the mitochondria.
E)  Myoglobin catalysis produces ATP.F) C) and D)
G) A) and C)

Question 20

A build-up of K⁺ in the T-tubules can occur during periods of frequent muscle cell potentials.What will be the result?

Accepted Answer

A)  Inhibition of neurotransmitter release from the motor neuron
B)  Inhibition of muscle cell depolarization and contraction
C)  Inhibition of relaxation,muscle stays in contracted state
D)  None of the answer choices are correctE) B) and D)
F) B) and C)

Exam 9: Muscle

Skeletal muscles are made up of bundles of muscle fibers attached to bone by connective tissue called tendons.

Correct AnswerverifiedShow Answer

If you took a drug that acts as an inhibitor of creatine kinase,you would still be able to contract your muscles,but in order to sustain a contraction you may notice an increase in ventilatory and heart rates.

Correct AnswerverifiedShow Answer

Which of the following statements regarding contraction in skeletal and smooth muscle is TRUE?

Correct AnswerverifiedShow Answer

If a biopsy of the quadriceps muscles (muscles on the front of the thigh) were taken from gold medal-winning speed skaters in the four following events,which would most likely have the SMALLEST percentage of type 1 muscle fibers?

Correct AnswerverifiedShow Answer

During isometric contraction of a skeletal muscle fiber,tension increases but the fiber length stays the same.

Correct AnswerverifiedShow Answer

Which of the following statements regarding myosin in skeletal muscle is TRUE?

Correct AnswerverifiedShow Answer

Which is a TRUE statement about excitation-contraction coupling?

Correct AnswerverifiedShow Answer

Multiunit smooth muscle cells

Correct AnswerverifiedShow Answer

Which is a TRUE statement about smooth muscle?

Correct AnswerverifiedShow Answer

Which best describes a "myofibril"?

Correct AnswerverifiedShow Answer

Why does breathing continue to be rapid and deep for a time after heavy exercise?

Correct AnswerverifiedShow Answer

Compared to type 1,both forms of type 2 muscle fibers usually have a large diameter.

Correct AnswerverifiedShow Answer

The decrease in mass and strength of muscle as a result of damage to the nerves innervating the muscle is called disuse atrophy.

Correct AnswerverifiedShow Answer

Which of the following statements regarding contraction of a skeletal muscle fiber is TRUE?

Correct AnswerverifiedShow Answer

Based on its molecular properties,nicotine will have what effect on skeletal muscle contraction?

Correct AnswerverifiedShow Answer

In the first few seconds of skeletal muscle contraction,what is the main mechanism by which ATP is replenished?

Correct AnswerverifiedShow Answer

A build-up of K⁺ in the T-tubules can occur during periods of frequent muscle cell potentials.What will be the result?

Correct AnswerverifiedShow Answer

Sarah is a girl with dreams of becoming an Olympic marathon runner.She just learned that she has a rare genetic mutation and does not produce functional creatine phosphate.What portion of Sarah's marathon experience will be effected?

Correct AnswerverifiedShow Answer

Which of the following properties of smooth muscle helps us to understand why,as pregnancy advances,women get more and more Braxton-Hicks (smooth muscle) contractions in the uterine wall?

Correct AnswerverifiedShow Answer

Tetanus toxin inhibits acetylcholinesterase activity.What will a person suffering from tetanus toxin poisoning look like?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified