Download Anatomy and Physiology - Problem Drill 09: Muscles and Muscle

Anatomy and Physiology - Problem Drill 09: Muscles and Muscle Tissue
Question No. 1 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go
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Question 1. Skeletal muscles ________.
A. Are striated, attached to bone they are generally under involuntary control.
B. Are made up of 2 fiber types: (a) red (slow-twitch) and (b) those with sarcomeres.
C. Are striated, attached to bone they are generally under voluntary control.
D. White (fast-twitch) fibers have more mitochondria and are associated with endurance.
Question
A. Incorrect!
Skeletal muscles are striated and attached to bone they are generally under voluntary control.
B. Incorrect!
Are made up of 2 fiber types: (a) red (slow-twitch) and (b) white (fast-twitch).
C. Correct!
Skeletal muscles are striated and attached to bone they are generally under voluntary control.
Feedback
D. Incorrect!
White (fast-twitch) fibers have fewer mitochondria and are explosive.
Skeletal muscle is striated, and attached to bones. Skeletal muscle facilitates movement by applying forces to bones
and joints through its contraction. They are generally under voluntary control.
Skeletal muscle has striations due to many sarcomeres (basic unit of contraction). Individual muscle myofibrils make up
a muscle fiber. There are 2 types of muscle fibers: (a) red (slow-twitch) have more mitochondria and are associated with
endurance (b) white (fast-twitch) have fewer mitochondria and are explosive.
Solution
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Question No. 2 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go
back to review the core concept tutorial as needed.
Question 2. Which of the following statements about sarcomeres is correct?
A. Sarcomeres are the basic unit of muscle, made up of actin and myosin.
B. Sliding filament model: the muscle generates its own signal to contract and then an action potential spreads over the
muscle fiber.
C. During muscular contraction ATP is formed.
D. During muscular contraction zinc is released and binds to tropomyosin, which unblocks actin-binding sites.
Question
A. Correct!
Sarcomeres are the basic unit of muscle, made up of actin and myosin.
B. Incorrect!
Sliding filament model: after the signal to contract comes from the central nervous system, an action potential spreads
over the muscle fiber.
C. Incorrect!
During muscular contraction ATP is hydrolyzed.
Feedback
D. Incorrect!
During muscular contraction calcium is released and binds to tropomyosin, which unblocks actin-binding sites.
Sarcomeres are the basic unit of muscle, made up of actin and myosin. Skeletal muscles contract according the sliding
filament model. Sliding filament model: after the signal to contract comes from the central nervous system, an action
potential spreads over the muscle fiber. Calcium is released and binds to tropomyosin; which unblocks actin binding
sites. Myosin (bound with ATP) binds to actin hydrolyzes ATP and the released energy delivers a power stroke. This
hydrolysis also causes the myosin head to turn and ratchet the Z lines closer together.
Solution
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Question No. 3 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go
back to review the core concept tutorial as needed.
Question 3. Which statement is true about cardiac muscle?
A. Cardiac muscle is a voluntary striated muscle found exclusively in the heart.
B. Stimulates its own contraction with the required electrical impulse from the central nervous system (CNS).
C. Special pacemaker cells in the sinoatrial node contract in response to the contraction rate of the adjacent skeletal
muscle.
D. Cardiac muscle is an involuntary striated muscle found exclusively in the heart.
Question
A. Incorrect!
Cardiac muscle is an involuntary striated muscle found exclusively in the heart.
B. Incorrect!
Stimulates its own contraction without the required electrical impulse from the central nervous system (CNS).
C. Incorrect!
Special pacemaker cells in the sinoatrial node spontaneously contract and send electrical impulses throughout the
heart.
Feedback
Solution
D. Correct!
Cardiac muscle is an involuntary striated muscle found exclusively in the heart.
Cardiac muscle is an involuntary striated muscle found exclusively in the heart. Cardiac muscle has unique properties:
(a) Stimulates its own contraction without the required electrical impulse from the central nervous system (CNS). (b)
Special pacemaker cells in the sinoatrial node (located in the right atrium), spontaneously contract and send electrical
impulses throughout the heart. (c) Normally the resting heart rate is between 70 – 80 bpm, determined by the
pacemaker cells. The CNS doesn’t directly create the impulse to contract, but modulates it through the autonomic
nervous system.
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Question No. 4 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go
back to review the core concept tutorial as needed.
Question 4. Which of the following statements about smooth muscle is correct?
A. Smooth muscle is a voluntary non-striated muscle found in the walls of hollow organs such as the bladder and in
blood vessels.
B. Smooth muscle can only be stimulated directly from the central nervous system.
C. Smooth muscle does not require ATP for contraction instead it contracts passively.
D. Smooth muscle is spindle-shaped and contains actin and myosin, although they are not arranged in a sarcomere.
Question
A. Incorrect!
Smooth muscle is an involuntary non-striated muscle found in the walls of hollow organs such as the bladder and in
blood vessels.
B. Incorrect!
Smooth muscle can be directly stimulated by the CNS or can react to hormones secreted locally, such as vasodilators
and vasoconstrictors.
C. Incorrect!
Smooth muscle hydrolyzes ATP and contracts by myosin and actin fibers sliding over each other.
Feedback
Solution
D. Correct!
Smooth muscle is spindle-shaped and contains actin and myosin, although they are not arranged in a sarcomere.
Smooth muscle is an involuntary non-striated muscle found in the walls of hollow organs such as the bladder, and in
blood vessels. Smooth muscle can be directly stimulated by the CNS or can react to hormones secreted locally, such as
vasodilators and vasoconstrictors. Smooth muscle is spindle shaped and contains actin and myosin, although there are
not arranged in a sarcomere. Smooth muscle hydrolyzes ATP and contracts by myosin and actin fibers sliding over
each other. Smooth muscle fibers are arranged in sheets within the walls of organs.
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Question No. 5 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go
back to review the core concept tutorial as needed.
Question 5. Which statement about excitation-contraction coupling is correct?
Question
A. Excitation-Contraction coupling is the process by which an action potential causes calcium (Ca2+) release and cross
bridge cycling.
B. Excitation-Contraction coupling is the process by which an action potential causes calcium (Ca2+) uptake and cross
bridge cycling.
C. Muscle cell depolarization leads to the release of Ca2+ into the sarcoplasmic reticulum, from the myoplasm.
D. Muscle cell depolarization leads to the uptake of Ca2+ into the sarcoplasmic reticulum, from the outside the muscle
cell.
A. Correct!
Excitation-Contraction coupling is the process by which an action potential causes calcium (Ca2+) release and cross
bridge cycling.
B. Incorrect!
Excitation-Contraction coupling is the process by which an action potential causes calcium (Ca2+) release and cross
bridge cycling.
C. Incorrect!
Muscle cell depolarization leads to the release of Ca2+ into the myoplasm, from the sarcoplasmic reticulum.
Feedback
D. Incorrect!
Muscle cell depolarization leads to the release of Ca2+ into the myoplasm, from the sarcoplasmic reticulum.
Excitation-Contraction coupling is the process by which an action potential causes calcium (Ca2+) release and cross
bridge cycling. An incoming action potential transmitted through the neuromuscular junction, causes the depolarization
of the skeletal muscle cell. Muscle cell depolarization leads to the release of Ca2+ into the myoplasm, from the
sarcoplasmic reticulum. Ca2+ release into the myoplasm binds to troponin and initiates contraction of the sarcomere.
Solution
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Question No. 6 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go
back to review the core concept tutorial as needed.
Question 6. Which statement is true about muscle contraction?
A. In order to recruit the entire muscle into contraction a sufficient number and intensity of stimuli is required.
B. In order to recruit the entire muscle into contraction the incoming stimulus must be slow.
C. If a single stimulus activates the muscle it will contract with all its fibers.
D. Repetitive stimulation is not necessary to activate the muscle into a complete contraction (tetanus) and to generate
the necessary force to complete the task.
Question
A. Correct!
In order to recruit the entire muscle into contraction a sufficient number and intensity of stimuli is required.
B. Incorrect!
In order to recruit the entire muscle into contraction a sufficient number and intensity of stimuli is required.
C. Incorrect!
If a single stimulus activates the muscle it will twitch and relax.
Feedback
D. Incorrect!
Repetitive stimulation is necessary to activate the muscle into a complete contraction (tetanus) and to generate the
necessary force to complete the task.
How much of the total skeletal muscle contracts depend on the stimulation pulse rate it receives. In order to recruit the
entire muscle into contraction a sufficient number and intensity of stimuli is required. If a single stimulus activates the
muscle it will twitch and relax. This occurs because Ca2+ is rapidly pumped back into the sarcoplasmic reticulum.
Repetitive stimulation is necessary to activate the muscle into a complete contraction (tetanus) and to generate the
necessary force to complete the task.
Solution
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Question No. 7 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go
back to review the core concept tutorial as needed.
Question 7. Which of the following statements about the length-tension relationship of a skeletal muscle is correct?
A. The optimal length for a muscle is when the least number of myosin cross bridges make contact with thin filaments.
B. As a muscle fiber is stretched the number of overlapping cross bridges increases and the tension generated
decreases.
C. How much tension (force of contraction) a skeletal muscle creates is not dependent on the length of the muscle itself.
D. How much tension (force of contraction) a skeletal muscle creates is dependent in part on the length of the muscle
itself.
Question
A. Incorrect!
The optimal length for a muscle is when the maximum number of myosin cross bridges make contact with thin filaments.
B. Incorrect!
As a muscle fiber is stretched the number of overlapping cross bridges decreases and the tension generated
decreases.
C. Incorrect!
How much tension (force of contraction) a skeletal muscle creates is dependent in part on the length of the muscle
itself.
Feedback
D. Correct!
How much tension (force of contraction) a skeletal muscle creates is dependent in part on the length of the muscle
itself.
How much tension (force of contraction) a skeletal muscle creates is dependent in part on the length of the muscle
itself.
The optimal length for a muscle is when the maximum number of myosin cross bridges make contact with thin filaments.
As a muscle fiber is stretched the number of overlapping cross bridges decreases and the tension generated
decreases.
Solution
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Question No. 8 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go
back to review the core concept tutorial as needed.
Question 8. Which of the following statements about muscle metabolism is correct?
A. Breakdown of ATP occurs towards the end of muscle contraction, lasting seconds.
B. Breakdown of ATP occurs when a muscle is stimulated to contract this is the initial energy source, lasting seconds.
C. Anaerobic Glycolysis is used when the there is an excess of oxygen available; muscle converts glucose into pyruvic
acid and ATP.
D. During the initial period of contraction of exercise muscle can use the byproducts of fat breakdown, free fatty acids
(FFA). FFA are converted into ATP.
Question
A. Incorrect!
Breakdown of ATP occurs when a muscle is stimulated to contract this is the initial energy source, lasting seconds.
B. Correct!
Breakdown of ATP occurs when a muscle is stimulated to contract this is the initial energy source, lasting seconds.
C. Incorrect!
Anaerobic Glycolysis: when the phosphocreatine source is depleted, muscle converts glucose into pyruvic acid and
ATP.
Feedback
Solution
D. Incorrect!
Lipolysis: during long periods of exercise muscle can use the byproducts of fat breakdown, free fatty acids (FFA). FFA
are converted into ATP.
Muscles utilize a variety of energy sources during contractions, these change over the time of contraction: (A)
Breakdown of ATP: when a muscle is stimulated to contract the initial ATP (stored as phosphocreatine) is the initial
energy source, lasting seconds. (B) Anaerobic Glycolysis: when the phosphocreatine source is depleted, muscle
converts glucose into pyruvic acid and ATP. (C) Aerobic Glycolysis: if sufficient oxygen is available muscle tissue will
convert glucose into CO2 H2O and ATP to use as energy. (D) Lipolysis: during long periods of exercise muscle can use
the byproducts of fat breakdown, free fatty acids (FFA). FFA are converted into ATP.
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Question No. 9 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go
back to review the core concept tutorial as needed.
Question 9. There are 3 types of skeletal muscle fibers and _______.
Question
A. Type IIa (fast oxidative-glycolytic) fibers contain few mitochondria and high levels of myoglobin. These fibers are
found infrequently.
B. Type IIb (fast glycolytic) fibers contain lots of mitochondria and low levels of myoglobin. They do however contain
large amount of glycogen. These fibers are found in arm muscles.
C. Type 1 (slow oxidative fibers) fibers contain many mitochondria and high levels of myoglobin. These fibers can be
found in neck muscles.
D. Type 1 (slow oxidative fibers) fibers contain few mitochondria and high levels of myoglobin. These fibers can be
found in neck muscles.
A. Incorrect!
Type IIa (fast oxidative-glycolytic) fibers contain lots of mitochondria and high levels of myoglobin. These fibers are
found infrequently.
B. Incorrect!
Type IIb (fast glycolytic) fibers contain few mitochondria and low levels of myoglobin. They do however contain large
amount of glycogen. These fibers are found in arm muscles.
C. Correct!
Type 1 (slow oxidative fibers) fibers contain many mitochondria and high levels of myoglobin. These fibers can be found
in neck muscles.
Feedback
Solution
D. Incorrect!
The Quadriceps Muscles are responsible for extending the leg and flex the thigh.
Type 1 (slow oxidative fibers) fibers contain many mitochondria and high levels of myoglobin. These fibers can be found
in neck muscles.
Type IIa (fast oxidative-glycolytic) fibers contain lots of mitochondria and high levels of myoglobin. These fibers are
found infrequently.
Type IIb (fast glycolytic) fibers contain few mitochondria and low levels of myoglobin. They do however contain large
amount of glycogen. These fibers are found in arm muscles.
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Question No. 10 of 10
Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go
back to review the core concept tutorial as needed.
Question 10. Which of the following statements about involuntary muscles is correct?
A. Involuntary muscles are rhythmic, automatically controlled muscles such as the biceps muscle.
B. Involuntary muscles are rhythmic, automatically controlled muscles such as cardiac muscle.
C. Examples of involuntarily controlled muscles are smooth muscle in the walls of organs and the masseter muscle.
D. The smooth muscle in arterioles can be contracted to decrease systemic blood pressure.
Question
A. Incorrect!
Involuntary muscles are rhythmic, automatically controlled muscles such as cardiac muscle.
B. Correct!
Involuntary muscles are rhythmic, automatically controlled muscles such as cardiac muscle.
C. Incorrect!
Examples of involuntarily controlled muscles are smooth muscle in the walls of organs, smooth muscle in blood vessels,
muscles of breathing and cardiac muscle.
Feedback
D. Incorrect!
The smooth muscle in arterioles can be contracted to increase systemic blood pressure.
Involuntary muscles are rhythmic, automatically controlled muscles. The muscles of breathing are under both voluntary
and involuntary control. Cardiac (heart) muscle is under involuntary control. The pacemaker cells in the sinoatrial node
set the rate and the autonomic nervous system can modulate that rate. Smooth muscles in the walls of organs and
blood vessels are primarily under involuntary control. The smooth muscle in arterioles can be contracted to increase
systemic blood pressure.
Solution
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