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Human Physiology
Muscle
Chapter 12
Skeletal Muscle Structure
A motor unit is
A. all the muscles that act as prime movers for a particular action.
B. the sarcomeres of an individual myofibril.
C. all of the neurons that stimulate a particular muscle.
D. a motor neuron and all the skeletal muscle fibers it innervates.
ANSWER
Skeletal Muscle Structure
A motor unit is
A. all the muscles that act as prime movers for a particular action.
B. the sarcomeres of an individual myofibril.
C. all of the neurons that stimulate a particular muscle.
D. a motor neuron and all the skeletal muscle fibers it innervates.
Skeletal Muscle Structure
Which anatomical feature of the skeletal
muscle cell allows the action potential to
stimulate the sarcoplasmic reticulum?
A. Transverse-tubule.
B. Sarcomere.
C. Myoglobin.
D. Troponin.
E. Cross-bridge.
ANSWER
Skeletal Muscle Structure
Which anatomical feature of the skeletal
muscle cell allows the action potential to
stimulate the sarcoplasmic reticulum?
A. Transverse-tubule.
B. Sarcomere.
C. Myoglobin.
D. Troponin.
E. Cross-bridge.
Mechanisms of Contraction
How is the calcium used for muscle contraction removed
from the cytoplasm so that relaxation may occur?
A. Active transport into the sarcoplasmic reticulum.
B. Active transport into the extracellular fluid.
C. Secondary active transport into the extracellular fluid.
D. Diffusion into the sarcoplasmic reticulum.
E. Diffusion into the extracellular fluid.
ANSWER
Mechanisms of Contraction
How is the calcium used for muscle contraction removed
from the cytoplasm so that relaxation may occur?
A. Active transport into the sarcoplasmic reticulum.
B. Active transport into the extracellular fluid.
C. Secondary active transport into the extracellular fluid.
D. Diffusion into the sarcoplasmic reticulum.
E. Diffusion into the extracellular fluid.
Skeletal Muscle Structure
Which of the following causes rigor in the skeletal
muscle?
A. Lack of action potentials.
B. Lack of ATP to return Ca+2 to endoplasmic reticulum.
C. An increase in intracellular Ca +2.
D. A decrease in intracellular Ca +2.
E. An increase in ATP.
ANSWER
Skeletal Muscle Structure
Which of the following causes rigor in the skeletal
muscle?
A. Lack of action potentials.
B. Lack of ATP to return Ca+2 to endoplasmic reticulum.
C. An increase in intracellular Ca +2.
D. A decrease in intracellular Ca +2.
E. An increase in ATP.
Mechanisms of Contraction
The energetics of the grip and re-grip action in the forming
and breaking of cross-bridges between myosin and actin
involves myosin heads requiring _______ for binding ;
______ for releasing from active sights on actin.
A. ADP ; ATP
B. phosphate; ADP
C. ATP ; ADP
D. ATP ; phosphate
ANSWER
Mechanisms of Contraction
The energetics of the grip and re-grip action in the forming
and breaking of cross-bridges between myosin and actin
involves myosin heads requiring _______ for binding ;
______ for releasing from active sights on actin.
A. ADP ; ATP
B. phosphate; ADP
C. ATP ; ADP
D. ATP ; phosphate
Mechanisms of Contraction
The strength with which a given muscle contracts is
affected by all of the following except the
A. frequency of stimulation.
B. strength of stimulation.
C. recruitment of additional motor neurons.
D. amount of glucose available for glycolysis.
E. The number of crossbridges formed between actin
and myosin.
ANSWER
Mechanisms of Contraction
The strength with which a given muscle contracts is
affected by all of the following except the
A. frequency of stimulation.
B. strength of stimulation.
C. recruitment of additional motor neurons.
D. amount of glucose available for glycolysis.
E. The number of crossbridges formed between actin
and myosin.
Mechanisms of Contraction
Place these events in the correct order of occurrence in the muscle contraction:
A. An action potential forms in muscle cell.
B. Action potential travels down transverse tubules into the interior of the muscle
fiber.
C. Acetylcholine binds to cholinergic receptors on the muscle cell membrane.
D. Calcium is released from the sarcoplasmic reticulum.
E. Na+ channels open leading to depolarization.
F. Muscle cell contracts.
G. Calcium ions bind to troponin, which then pull on tropomyosin.
Correct order is: __ → _ _→ _ → _ →_ → _ → _.
ANSWER
Mechanisms of Contraction
Place these events in the correct order of occurrence in the muscle contraction:
A. An action potential forms in muscle cell.
B. Action potential travels down transverse tubules into the interior of the muscle
fiber.
C. Acetylcholine binds to cholinergic receptors on the muscle cell membrane.
D. Calcium is released from the sarcoplasmic reticulum.
E. Na+ channels open leading to depolarization.
F. Muscle cell contracts.
G. Calcium ions bind to troponin, which then pull on tropomyosin.
Correct order is: C → E → A → B →D → E → F.
Energy for Contraction
Phosphocreatine
A. Has two isoforms in muscle.
B. Serves as a ready reserve of high-energy phosphate.
C. An intermediate in the metabolism of glucose.
D. both A and B.
E. both B and C.
ANSWER
Energy for Contraction
Phosphocreatine
A. Has two isoforms in muscle.
B. Serves as a ready reserve of high-energy phosphate.
C. An intermediate in the metabolism of glucose.
D. both A and B.
E. both B and C.
Energy for Contraction
A warm up period prior to exercise is to take
advantage of ___.
A. Incomplete tetanus
B. tetanus
C. treppe
D. recruitment
ANSWER
Energy for Contraction
A warm up period prior to exercise is to take
advantage of ___.
A. Incomplete tetanus
B. tetanus
C. treppe
D. recruitment
Energy for Contraction
A drug that blocks the acetylcholine receptors on
muscle fibers would
A. produce a stronger muscle contraction.
B. produce muscle spasms.
C. cause spastic paralysis (hypertonia).
D. cause flaccid paralysis (hypotonia).
ANSWER
Energy for Contraction
A drug that blocks the acetylcholine receptors on
muscle fibers would
A. produce a stronger muscle contraction.
B. produce muscle spasms.
C. cause spastic paralysis (hypertonia).
D. cause flaccid paralysis (hypotonia).
Contrasts Among Muscle Types
Which of the following does NOT apply to cardiac
muscle when compared with skeletal and smooth
muscle?
A. It is autorhythmic.
B. It is influenced by ACh and epinephrine.
C. It has the slowest contraction speed.
D. It is under autonomic control.
E. ACh stimulation slows while epinephrine stimulation
speeds rate of contraction.
F. It is fatigue resistant.
ANSWER
Contrasts Among Muscle Types
Which of the following does NOT apply to cardiac
muscle when compared with skeletal and smooth
muscle?
A. It is autorhythmic.
B. It is influenced by ACh and epinephrine.
C. It has the slowest contraction speed.
D. It is under autonomic control.
E. ACh stimulation slows while epinephrine stimulation
speeds rate of contraction.
F. It is fatigue resistant.
Contrasts Among Muscle Types
Which of the following does NOT apply to skeletal
muscle when compared with cardiac muscle?
A. It is stimulated by somatic motor neurons.
B. ACh stimulation slows while epinephrine stimulation
speeds rate of contraction.
C. It has the fastest contraction speed.
D. It is under voluntary control.
E. It involves nicotinic cholinergic receptors.
F. It is prone to fatigue.
ANSWER
Contrasts Among Muscle Types
Which of the following does NOT apply to skeletal
muscle when compared with cardiac muscle?
A. It is stimulated by somatic motor neurons.
B. ACh stimulation slows while epinephrine stimulation
speeds rate of contraction.
C. It has the fastest contraction speed.
D. It is under voluntary control.
E. It involves nicotinic cholinergic receptors.
F. It is prone to fatigue.
Disorders of Muscle
A disorder characterized by loss of motor control of
muscles due to an excess of glutamate and a loss
of superoxide dismutase.
A. Myasthenia gravis.
B. Alzheimer’s.
C. ALS.
D. Multiple sclerosis.
E. Duchene’s MD
ANSWER
Disorders of Muscle
A disorder characterized by loss of motor control of
muscles due to an excess of glutamate and a loss
of superoxide dismutase.
A. Myasthenia gravis.
B. Alzheimer’s.
C. ALS.
D. Multiple sclerosis.
E. Duchene’s MD
Disorders of Muscle
A disorder characterized by loss of motor control of
muscles due to autoimmune attack of cholinergic
receptors on muscle cells.
A. Myasthenia gravis.
B. Alzheimer’s.
C. ALS.
D. Multiple sclerosis.
E. Duchene’s MD
ANSWER
Disorders of Muscle
A disorder characterized by loss of motor control of
muscles due to autoimmune attack of cholinergic
receptors on muscle cells.
A. Myasthenia gravis.
B. Alzheimer’s.
C. ALS.
D. Multiple sclerosis.
E. Duchene’s MD
Neural Control of Skeletal Muscle
If the interneurons can stimulate the agonist muscle
fibers and inhibit their antagonist muscles, it
illustrates the principle of
A. reverberating circuitry.
B. generalized facilitation.
C. reinforcement.
D. reciprocal innervation.
ANSWER
Neural Control of Skeletal Muscle
If the interneurons can stimulate the agonist muscle
fibers and inhibit their antagonist muscles, it
illustrates the principle of
A. reverberating circuitry.
B. generalized facilitation.
C. reinforcement.
D. reciprocal innervation.
Neural Control of Skeletal Muscle
The muscle sensory organ that detects tension
(pull) on a muscle.
A. Muscle spindle
B. Golgi tendon
C. Sarcomere
D. Transverse tubule
ANSWER
Neural Control of Skeletal Muscle
The muscle sensory organ that detects tension
(pull) on a muscle.
A. Muscle spindle
B. Golgi tendon
C. Sarcomere
D. Transverse tubule
Neural Control of Skeletal Muscle
Upper motor neurons originate primarily in
A. the spinal cord.
B. the peripheral spinal nerves.
C. the primary motor cortex.
D. the brainstem.
ANSWER
Neural Control of Skeletal Muscle
Upper motor neurons originate primarily in
A. the spinal cord.
B. the peripheral spinal nerves.
C. the primary motor cortex.
D. the brainstem.
Neural Control of Skeletal Muscle
These neurons innervate intrafusal (stretch) muscle
fibers of the muscle spindle apparatus and
stimulate isometric contraction.
A. Gamma motor neurons.
B. Upper motor neurons.
C. Alpha motor neurons.
D. Beta motor neurons.
ANSWER
Neural Control of Skeletal Muscle
These neurons innervate intrafusal (stretch) muscle
fibers of the muscle spindle apparatus and
stimulate isometric contraction.
A. Gamma motor neurons.
B. Upper motor neurons.
C. Alpha motor neurons.
D. Beta motor neurons.
Neural Control of Skeletal Muscle
This type of reflex involves muscle ipsilateral (one
body side only) action where a muscle stretch
contracts one muscle group and relaxes its
antagonist muscle group.
A. Monosynaptic reflex.
B. Crossed Extensor reflex.
C. Disynaptic reflex.
D. Reciprocal innervation reflex.
ANSWER
Neural Control of Skeletal Muscle
This type of reflex involves muscle ipsilateral (one
body side only) action where a muscle stretch
contracts one muscle group and relaxes its
antagonist muscle group.
A. Monosynaptic reflex.
B. Crossed Extensor reflex.
C. Disynaptic reflex.
D. Reciprocal innervation reflex.
Neural Control of Skeletal Muscle
______ are thinner and slower motor fibers that
innervate the ______.
A. Gamma motor neurons; extrafusal fibers.
B. Gamma motor neurons; intrafusal fibers.
C. Alpha motor neurons; extrafusal fibers.
D. Alpha motor neurons; intrafusal fibers.
ANSWER
Neural Control of Skeletal Muscle
______ are thinner and slower motor fibers that
innervate the ______.
A. Gamma motor neurons; extrafusal fibers.
B. Gamma motor neurons; intrafusal fibers.
C. Alpha motor neurons; extrafusal fibers.
D. Alpha motor neurons; intrafusal fibers.
Neural Control of Skeletal Muscle
Which reflex is responsible for monosynaptic
ipsilateral (one body side only) excitation of the
muscle?
A. Golgi tendon reflex.
B. Flexor withdrawal reflex.
C. Crossed-extensor reflex.
D. Stretch reflex.
E. Inverse stretch reflex.
ANSWER
Neural Control of Skeletal Muscle
Which reflex is responsible for monosynaptic
ipsilateral (one body side only) excitation of the
muscle?
A. Golgi tendon reflex.
B. Flexor withdrawal reflex.
C. Crossed-extensor reflex.
D. Stretch reflex.
E. Inverse stretch reflex.
Neural Control of Skeletal Muscle
If you were to step on a piece of broken glass with your
bare left foot, which of the following does not happen?
A. Extensor muscles of the left leg are inhibited.
B. Extensor muscles of the right leg are stimulated.
C. A polysynaptic reflex occurs.
D. Flexor muscles of the left leg are stimulated.
E. Flexor muscles of the left leg are inhibited.
ANSWER
Neural Control of Skeletal Muscle
If you were to step on a piece of broken glass with your
bare left foot, which of the following does not happen?
A. Extensor muscles of the left leg are inhibited.
B. Extensor muscles of the right leg are stimulated.
C. A polysynaptic reflex occurs.
D. Flexor muscles of the left leg are stimulated.
E. Flexor muscles of the left leg are inhibited.