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Questions and Answers
What causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum within a muscle cell?
What causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum within a muscle cell?
Arrival of an action potential.
The binding of calcium to which molecule causes the myosin binding sites to be exposed?
The binding of calcium to which molecule causes the myosin binding sites to be exposed?
Protein complex.
A myosin head binds to which molecule to form a cross bridge?
A myosin head binds to which molecule to form a cross bridge?
Actin.
What causes the myosin head to disconnect from actin?
What causes the myosin head to disconnect from actin?
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What energizes the power stroke?
What energizes the power stroke?
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Which of the following proteins makes up the thick filament of the sarcomeres?
Which of the following proteins makes up the thick filament of the sarcomeres?
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Which statement describes the sliding-filament theory?
Which statement describes the sliding-filament theory?
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T tubules are an invagination of the ________.
T tubules are an invagination of the ________.
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What is the function of calcium ions in the contraction of a muscle (sarcomere)?
What is the function of calcium ions in the contraction of a muscle (sarcomere)?
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Complete this sentence: As the sarcomere contracts, ________.
Complete this sentence: As the sarcomere contracts, ________.
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Which of the following choices arranges the structures (1) muscle fiber, (2) fascicle, (3) myofibril, and (4) muscle from largest (most inclusive) to smallest?
Which of the following choices arranges the structures (1) muscle fiber, (2) fascicle, (3) myofibril, and (4) muscle from largest (most inclusive) to smallest?
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What is the first and most direct energy source for muscle contraction?
What is the first and most direct energy source for muscle contraction?
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Which of the following best describes the action of sarcomeres within a muscle cell during a contraction?
Which of the following best describes the action of sarcomeres within a muscle cell during a contraction?
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Which term describes the subunits of a myofibril?
Which term describes the subunits of a myofibril?
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Which of the following structures is not contained within a muscle fiber?
Which of the following structures is not contained within a muscle fiber?
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Muscle fibers are among the largest cells in the body and are actually fusions of hundreds of individual cells.
Muscle fibers are among the largest cells in the body and are actually fusions of hundreds of individual cells.
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The thick filaments of sarcomeres are composed of _____?
The thick filaments of sarcomeres are composed of _____?
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The thin filaments of sarcomeres are composed of _____?
The thin filaments of sarcomeres are composed of _____?
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A single muscle cell is referred to as a _____.
A single muscle cell is referred to as a _____.
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What is the type of chemical reaction used to rebuild ADP into ATP?
What is the type of chemical reaction used to rebuild ADP into ATP?
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Which of the following processes produces molecules of ATP and has two pyruvic acid molecules as end products?
Which of the following processes produces molecules of ATP and has two pyruvic acid molecules as end products?
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Which of the following processes produces 36 ATP?
Which of the following processes produces 36 ATP?
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The 'rest and recovery' period, where the muscle restores depleted reserves, includes all of the following processes EXCEPT __________.
The 'rest and recovery' period, where the muscle restores depleted reserves, includes all of the following processes EXCEPT __________.
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Which type of muscle fiber has a large quantity of glycogen and mainly uses glycolysis to synthesize ATP?
Which type of muscle fiber has a large quantity of glycogen and mainly uses glycolysis to synthesize ATP?
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Muscles that oppose each other and produce opposite movements are described as __________.
Muscles that oppose each other and produce opposite movements are described as __________.
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All of the following are functions of the muscular system, EXCEPT __________.
All of the following are functions of the muscular system, EXCEPT __________.
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Which of the following happens during muscle contraction?
Which of the following happens during muscle contraction?
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When a skeletal muscle contracts, the __________ is pulled toward the __________.
When a skeletal muscle contracts, the __________ is pulled toward the __________.
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Arrange the following components of a muscle in order of increasing size.
Arrange the following components of a muscle in order of increasing size.
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When a muscle contracts, shortening of the muscle occurs because __________.
When a muscle contracts, shortening of the muscle occurs because __________.
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In a muscle cell, __________ contain __________.
In a muscle cell, __________ contain __________.
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During the course of muscle contraction, the potential energy stored in ATP is transferred to potential energy stored in _____?
During the course of muscle contraction, the potential energy stored in ATP is transferred to potential energy stored in _____?
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The release of _____ ions from the sarcoplasmic reticulum is required for skeletal muscle contraction.
The release of _____ ions from the sarcoplasmic reticulum is required for skeletal muscle contraction.
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Myosin heads bind to _____, which they then pull and cause to slide toward the center of the sarcomere.
Myosin heads bind to _____, which they then pull and cause to slide toward the center of the sarcomere.
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Of these events, the first to occur when a motor neuron stops sending an impulse to a muscle is _____.
Of these events, the first to occur when a motor neuron stops sending an impulse to a muscle is _____.
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A muscle cell contains bundles of long _____?
A muscle cell contains bundles of long _____?
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When a sarcomere contracts, _____?
When a sarcomere contracts, _____?
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Which of the following events is the direct result of an action potential in the membrane of a muscle cell?
Which of the following events is the direct result of an action potential in the membrane of a muscle cell?
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When ATP attaches to a myosin head, _____?
When ATP attaches to a myosin head, _____?
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Calcium ions _____?
Calcium ions _____?
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Botulism toxin inhibits the release of acetylcholine at the neuromuscular junctions. What effect does this have on the muscle activity?
Botulism toxin inhibits the release of acetylcholine at the neuromuscular junctions. What effect does this have on the muscle activity?
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The sliding filament mechanism describes the process during which __________.
The sliding filament mechanism describes the process during which __________.
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Which of the following is the site of calcium ion storage within muscles?
Which of the following is the site of calcium ion storage within muscles?
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What is the role of ATP in muscle function?
What is the role of ATP in muscle function?
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In the sliding-filament mechanism of muscle contraction, __________ slides over __________.
In the sliding-filament mechanism of muscle contraction, __________ slides over __________.
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Which of the following would interfere most with a muscle's ability to contract?
Which of the following would interfere most with a muscle's ability to contract?
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When a muscle relaxes, ATP is required. The reason for this is that __________.
When a muscle relaxes, ATP is required. The reason for this is that __________.
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All of the following may happen in response to exercise training, EXCEPT __________.
All of the following may happen in response to exercise training, EXCEPT __________.
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Which of the following is/are characteristic of slow-twitch fibers?
Which of the following is/are characteristic of slow-twitch fibers?
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Which of the following would have motor units with the smallest number of muscle cells?
Which of the following would have motor units with the smallest number of muscle cells?
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The all-or-none principle states that __________.
The all-or-none principle states that __________.
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Tetanic contractions result from __________.
Tetanic contractions result from __________.
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Which of the following is the same in both slow-twitch and fast-twitch muscle fibers?
Which of the following is the same in both slow-twitch and fast-twitch muscle fibers?
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Which type(s) of muscle cells can contract the fastest?
Which type(s) of muscle cells can contract the fastest?
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Which type(s) of muscle cells can contract spontaneously?
Which type(s) of muscle cells can contract spontaneously?
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Which of the following disorders of the muscular system is INCORRECTLY described?
Which of the following disorders of the muscular system is INCORRECTLY described?
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Steroid use in men may lead to __________.
Steroid use in men may lead to __________.
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Study Notes
Muscle Contraction Mechanism
- An action potential in the T tubule prompts calcium release from the terminal cisternae of the sarcoplasmic reticulum, initiating muscle contraction.
- Calcium binds to the troponin-tropomyosin complex, exposing myosin binding sites on actin.
Myosin and Actin Interaction
- Myosin heads attach to actin, forming a cross bridge and enabling the power stroke.
- The power stroke is fueled by ATP hydrolysis, which transfers energy to the myosin head.
- Upon ATP binding, myosin heads detach from actin.
Sarcomere Structure and Function
- Thick filaments composed of myosin; thin filaments composed of actin.
- Sarcomeres are the subunits of myofibrils, contracting by the sliding filament theory where actin is pulled over myosin.
Muscle Fiber Composition
- Muscle fibers consist of myofibrils that contain actin and myosin filaments, localized within a single muscle fiber.
- Muscle cells, known as fibers, are among the largest in the body, formed from the fusion of multiple cells.
Energy Sources in Muscle Contraction
- ATP is the primary energy source for muscle contraction.
- Dehydration synthesis rebuilds ADP into ATP, while glycolysis creates two pyruvic acid molecules from glucose.
- Aerobic respiration through the Krebs cycle produces up to 36 ATP per glucose molecule.
Muscle Fiber Types
- White fast twitch fibers are adapted for anaerobic glycolysis and have high glycogen content, which supports rapid, powerful contractions with limited oxygen supply.
- Slow-twitch fibers possess high myoglobin content and numerous mitochondria, making them suited for endurance and sustained activities.
Muscle Interaction
- Antagonistic muscles produce opposite movements to facilitate movement control.
- The sliding filament mechanism describes actin sliding over myosin during contraction.
Calcium Ions in Muscle Function
- Calcium ions are stored in the sarcoplasmic reticulum and are essential for muscle contraction.
- The release of calcium triggers the interaction between actin and myosin, leading to muscle contraction.
Muscle Relaxation Process
- Muscle relaxation involves the pumping of calcium ions back into the sarcoplasmic reticulum, ceasing contractions.
- ATP is necessary for myosin heads to detach from actin, enabling the muscle to relax.
Motor Units and Muscle Fiber Recruitment
- Smaller motor units are found in muscles like those in the fingers for fine motor control.
- The all-or-none principle indicates that muscle cells respond completely or not at all when stimulated.
Effects of Exercise and Training
- Muscle training can lead to adaptations such as increased myoglobin and mitochondrial content but does not increase the number of muscle fibers.
Disorders and Implications
- Muscular dystrophy is characterized incorrectly as a viral disease; it is a genetic condition leading to muscle wasting.
- Steroid use in men can cause irreversible changes in body composition and function.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge of muscle physiology concepts with these flashcards from Chapter 6. Learn about the role of calcium in muscle contraction and how it interacts with key proteins. Use this quiz to reinforce your understanding of critical physiological processes.
