Question 1

Which of these occurs during an isometric contraction of a skeletal muscle?

Accepted Answer

A)  The I bands shorten and the A bands stay the same length. 
B)  The thick and thin filaments slide past each other. 
C)  Sarcomere length does not change significantly. 
D)  The A bands shorten and the I bands stay the same length. 
E)  Cross-bridges lock onto actin, similar to what occurs in rigor mortis. 
A)  The I bands shorten and the A bands stay the same length. 
B)  The thick and thin filaments slide past each other. 
C)  Sarcomere length does not change significantly. 
D)  The A bands shorten and the I bands stay the same length. 
E)  Cross-bridges lock onto actin, similar to what occurs in rigor mortis. C

Question 2

Binding of myosin to actin in skeletal muscle cells does not normally take place in the absence of Ca2+.

Accepted Answer

A) True 
 B)False  True

Question 3

Compared to type I (slow oxidative) skeletal muscle fibers, how are type IIb (fast-glycolytic) skeletal muscle fibers different?

Accepted Answer

A)  Type IIb fibers have more abundant mitochondria. 
B)  Type IIb fibers fatigue more readily. 
C)  Type IIb fibers have more abundant myoglobin. 
D)  Type IIb fibers are smaller in diameter. 
E)  Type IIb motor units contain fewer fibers per alpha motor neuron. 
A)  Type IIb fibers have more abundant mitochondria. 
B)  Type IIb fibers fatigue more readily. 
C)  Type IIb fibers have more abundant myoglobin. 
D)  Type IIb fibers are smaller in diameter. 
E)  Type IIb motor units contain fewer fibers per alpha motor neuron. B

Question 4

Abundant mitochondria are typical of which type of skeletal muscle fibers?

Accepted Answer

A)  Type I 
B)  Type II 
A)  Type I 
B)  Type II

Question 5

Which type of skeletal muscle fibers fatigues most quickly?

Accepted Answer

A)  Type I 
B)  Type II 
A)  Type I 
B)  Type II

Question 6

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. 
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.

Question 7

Fast fibers can be distinguished from slow fibers by the rate at which their myosin-ATPases split ATP.

Accepted Answer

A) True 
 B)False

Question 8

The latent period of an isotonic twitch is shorter than the latent period of an isometric twitch.

Accepted Answer

A) True 
 B)False

Question 9

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

Accepted Answer

A)  Only one cross-bridge cycle can occur when the [Ca2+] is elevated in the cytosol; in order to undergo a second cycle, [Ca2+] must be sequestered in the sarcoplasmic reticulum and released again. 
B)  ATP hydrolysis products must be removed from myosin before it can bind to actin. 
C)  Binding of myosin to actin takes place when [Ca2+] increases in the cytosol. 
D)  A single twitch in skeletal muscle lasts the same length of time as the action potential that causes it. 
E)  The powerstroke of the cross-bridge cycle occurs simultaneously with ATP being hydrolyzed into ADP and Pi. 
A)  Only one cross-bridge cycle can occur when the [Ca2+] is elevated in the cytosol; in order to undergo a second cycle, [Ca2+] must be sequestered in the sarcoplasmic reticulum and released again. 
B)  ATP hydrolysis products must be removed from myosin before it can bind to actin. 
C)  Binding of myosin to actin takes place when [Ca2+] increases in the cytosol. 
D)  A single twitch in skeletal muscle lasts the same length of time as the action potential that causes it. 
E)  The powerstroke of the cross-bridge cycle occurs simultaneously with ATP being hydrolyzed into ADP and Pi.

Question 10

Binding of ________ to myosin permits cross-bridge _____________ between actin and myosin in skeletal muscle cells.

Accepted Answer

A)  ATP; attachment 
B)  ATP; detachment 
C)  calcium; attachment 
D)  calcium; detachment 
E)  actin; detachment 
A)  ATP; attachment 
B)  ATP; detachment 
C)  calcium; attachment 
D)  calcium; detachment 
E)  actin; detachment

Question 11

Characteristics of slow-oxidative fibers include numerous mitochondria, abundant myoglobin, and large stores of glycogen.

Accepted Answer

A) True 
 B)False

Question 12

During concentric contractions of skeletal muscle, the I band and H zone shorten but the A band stays the same.

Accepted Answer

A) True 
 B)False

Question 13

In general, activating a slow-oxidative motor unit in a muscle will generate more tension than activating a fast-glycolytic motor unit.

Accepted Answer

A) True 
 B)False

Question 14

The step of the cross-bridge cycle that immediately follows the attachment of ATP to the myosin head is referred to as the "powerstroke."

Accepted Answer

A) True 
 B)False

Question 15

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

Accepted Answer

A)  Extra oxygen is needed to eliminate lactic acid and restore muscle creatine phosphate and glucose concentrations. 
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. 
A)  Extra oxygen is needed to eliminate lactic acid and restore muscle creatine phosphate and glucose concentrations. 
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.

Question 16

Which of the following statements about different kinds of skeletal muscle fibers is TRUE?

Accepted Answer

A)  Slow-oxidative fibers have a greater abundance of glycogen than do fast-glycolytic fibers. 
B)  Fast-glycolytic fibers have a greater abundance of myoglobin than do slow-oxidative fibers. 
C)  A fast-glycolytic fiber can generate greater tension than a slow-oxidative fiber. 
D)  Fast-glycolytic fibers and slow-oxidative fibers are innervated by alpha motor neurons of the same diameter. 
E)  To generate ATP, fast-glycolytic fibers depend mainly on oxidative phosphorylation while slow-oxidative fibers depend mainly on glycolysis. 
A)  Slow-oxidative fibers have a greater abundance of glycogen than do fast-glycolytic fibers. 
B)  Fast-glycolytic fibers have a greater abundance of myoglobin than do slow-oxidative fibers. 
C)  A fast-glycolytic fiber can generate greater tension than a slow-oxidative fiber. 
D)  Fast-glycolytic fibers and slow-oxidative fibers are innervated by alpha motor neurons of the same diameter. 
E)  To generate ATP, fast-glycolytic fibers depend mainly on oxidative phosphorylation while slow-oxidative fibers depend mainly on glycolysis.

Question 17

John is a sprinter who specializes in quick and powerful bursts of speed followed by periods of rest. Jim is a marathon runner who specializes in long, steady runs. Compared to Jim, John is likely to have:

Accepted Answer

A)  legs with a larger diameter. 
B)  legs with a smaller diameter. 
C)  hypertrophy of type I muscle fibers. 
D)  a higher density of capillaries in his legs. 
E)  lower concentrations of glycolytic enzymes in his leg muscles. 
A)  legs with a larger diameter. 
B)  legs with a smaller diameter. 
C)  hypertrophy of type I muscle fibers. 
D)  a higher density of capillaries in his legs. 
E)  lower concentrations of glycolytic enzymes in his leg muscles.

Question 18

A large diameter is typical of which type of skeletal muscle fibers?

Accepted Answer

A)  Type I 
B)  Type II 
A)  Type I 
B)  Type II

Question 19

What is the definition of a "motor unit"?

Accepted Answer

A)  a single motor neuron plus all the muscle fibers it innervates 
B)  a single muscle fiber plus all of the motor neurons that innervate it 
C)  all of the motor neurons supplying a single muscle 
D)  a pair of antagonistic muscles 
E)  all of the muscles that affect the movement of any given joint 
A)  a single motor neuron plus all the muscle fibers it innervates 
B)  a single muscle fiber plus all of the motor neurons that innervate it 
C)  all of the motor neurons supplying a single muscle 
D)  a pair of antagonistic muscles 
E)  all of the muscles that affect the movement of any given joint

Question 20

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. 
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.

Which of these occurs during an isometric contraction of a skeletal muscle?

Binding of myosin to actin in skeletal muscle cells does not normally take place in the absence of Ca²⁺.

Compared to type I (slow oxidative) skeletal muscle fibers, how are type IIb (fast-glycolytic) skeletal muscle fibers different?

Abundant mitochondria are typical of which type of skeletal muscle fibers?

Which type of skeletal muscle fibers fatigues most quickly?

Which is a TRUE statement about excitation-contraction coupling?

Fast fibers can be distinguished from slow fibers by the rate at which their myosin-ATPases split ATP.

The latent period of an isotonic twitch is shorter than the latent period of an isometric twitch.

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

Binding of to myosin permits cross-bridge _____ between actin and myosin in skeletal muscle cells.

Characteristics of slow-oxidative fibers include numerous mitochondria, abundant myoglobin, and large stores of glycogen.

During concentric contractions of skeletal muscle, the I band and H zone shorten but the A band stays the same.

In general, activating a slow-oxidative motor unit in a muscle will generate more tension than activating a fast-glycolytic motor unit.

The step of the cross-bridge cycle that immediately follows the attachment of ATP to the myosin head is referred to as the "powerstroke."

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

Which of the following statements about different kinds of skeletal muscle fibers is TRUE?

John is a sprinter who specializes in quick and powerful bursts of speed followed by periods of rest. Jim is a marathon runner who specializes in long, steady runs. Compared to Jim, John is likely to have:

A large diameter is typical of which type of skeletal muscle fibers?

What is the definition of a "motor unit"?

Which is a TRUE statement about smooth muscle?

Homeostasis: a Framework for Human Physiology

Chemical Composition of the Body and Its Relation to Physiology

Cellular Structure, Proteins, and Metabolic Pathways

Movement of Molecules Across Cell Membranes

Cell Signaling in Physiology

Neuronal Signaling and the Structure of the Nervous System

Sensory Physiology

Consciousness, the Brain, and Behavior

Control of Body Movement

The Endocrine System

Cardiovascular Physiology

Respiratory Physiology

The Kidneys and Regulation of Water and Inorganic Ions

The Digestion and Absorption of Food

Regulation of Organic Metabolism and Energy Balance

Reproduction

The Immune System

Filters

Exam 9: Muscle

Which of these occurs during an isometric contraction of a skeletal muscle?

Binding of myosin to actin in skeletal muscle cells does not normally take place in the absence of Ca2+.

Compared to type I (slow oxidative) skeletal muscle fibers, how are type IIb (fast-glycolytic) skeletal muscle fibers different?

Abundant mitochondria are typical of which type of skeletal muscle fibers?

Which type of skeletal muscle fibers fatigues most quickly?

Which is a TRUE statement about excitation-contraction coupling?

Fast fibers can be distinguished from slow fibers by the rate at which their myosin-ATPases split ATP.

The latent period of an isotonic twitch is shorter than the latent period of an isometric twitch.

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

Binding of ________ to myosin permits cross-bridge _____________ between actin and myosin in skeletal muscle cells.

Characteristics of slow-oxidative fibers include numerous mitochondria, abundant myoglobin, and large stores of glycogen.

During concentric contractions of skeletal muscle, the I band and H zone shorten but the A band stays the same.

In general, activating a slow-oxidative motor unit in a muscle will generate more tension than activating a fast-glycolytic motor unit.

The step of the cross-bridge cycle that immediately follows the attachment of ATP to the myosin head is referred to as the "powerstroke."

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

Which of the following statements about different kinds of skeletal muscle fibers is TRUE?

John is a sprinter who specializes in quick and powerful bursts of speed followed by periods of rest. Jim is a marathon runner who specializes in long, steady runs. Compared to Jim, John is likely to have:

A large diameter is typical of which type of skeletal muscle fibers?

What is the definition of a "motor unit"?

Which is a TRUE statement about smooth muscle?

Homeostasis: a Framework for Human Physiology

Chemical Composition of the Body and Its Relation to Physiology

Cellular Structure, Proteins, and Metabolic Pathways

Movement of Molecules Across Cell Membranes

Cell Signaling in Physiology

Neuronal Signaling and the Structure of the Nervous System

Sensory Physiology

Consciousness, the Brain, and Behavior

Control of Body Movement

The Endocrine System

Cardiovascular Physiology

Respiratory Physiology

The Kidneys and Regulation of Water and Inorganic Ions

The Digestion and Absorption of Food

Regulation of Organic Metabolism and Energy Balance

Reproduction

The Immune System

Filters

Binding of myosin to actin in skeletal muscle cells does not normally take place in the absence of Ca²⁺.

Binding of to myosin permits cross-bridge _____ between actin and myosin in skeletal muscle cells.