Podcast
Questions and Answers
Which property of muscle cells allows them to return to their original shape after being stretched?
Which property of muscle cells allows them to return to their original shape after being stretched?
- Extensibility
- Plasticity
- Elasticity (correct)
- Contractility
What is the primary role of actin and myosin in muscle contraction?
What is the primary role of actin and myosin in muscle contraction?
- To interact and shorten the sarcomere (correct)
- To provide energy for the contraction
- To stabilize the muscle structure
- To transport calcium ions
What structure surrounds an entire skeletal muscle?
What structure surrounds an entire skeletal muscle?
- Perimysium
- Myofibrils
- Endomysium
- Epimysium (correct)
Which protein blocks the binding sites on actin to prevent contraction when muscle is at rest?
Which protein blocks the binding sites on actin to prevent contraction when muscle is at rest?
What initiates an action potential in the muscle cell at the neuromuscular junction?
What initiates an action potential in the muscle cell at the neuromuscular junction?
Which of the following structures is located inside muscle fibers and composed of sarcomeres?
Which of the following structures is located inside muscle fibers and composed of sarcomeres?
Which characteristic of muscle cells allows them to adapt to various lengths and forces?
Which characteristic of muscle cells allows them to adapt to various lengths and forces?
What role does troponin play in muscle contraction?
What role does troponin play in muscle contraction?
Which type of muscle is characterized by involuntary, rhythmic contractions and is found in the heart?
Which type of muscle is characterized by involuntary, rhythmic contractions and is found in the heart?
What initiates the release of calcium ions from the sarcoplasmic reticulum?
What initiates the release of calcium ions from the sarcoplasmic reticulum?
What is the primary function of smooth muscle?
What is the primary function of smooth muscle?
What distinguishes asynchronous muscle found in certain insects?
What distinguishes asynchronous muscle found in certain insects?
Which role does troponin play during muscle contraction?
Which role does troponin play during muscle contraction?
Which energy system primarily provides high-intensity output for quick bursts of activity?
Which energy system primarily provides high-intensity output for quick bursts of activity?
What is the primary function of ATPase in muscle contraction?
What is the primary function of ATPase in muscle contraction?
Skeletal muscle is known for which of the following characteristics?
Skeletal muscle is known for which of the following characteristics?
What mechanism allows muscles to generate movement when attached to an exoskeleton?
What mechanism allows muscles to generate movement when attached to an exoskeleton?
Which type of muscle cell is characterized by its quick contractions but rapid fatigue?
Which type of muscle cell is characterized by its quick contractions but rapid fatigue?
What role does calcium play in the contraction cycle of muscles?
What role does calcium play in the contraction cycle of muscles?
Which of the following is a characteristic of the glycolytic energy system?
Which of the following is a characteristic of the glycolytic energy system?
Which material in the skeleton aids in increasing the leverage of muscle contractions?
Which material in the skeleton aids in increasing the leverage of muscle contractions?
What happens to calcium ions when the action potential ceases?
What happens to calcium ions when the action potential ceases?
Which muscle type is specialized for rapid and sustained flight in both birds and insects?
Which muscle type is specialized for rapid and sustained flight in both birds and insects?
Which muscle cell type primarily utilizes aerobic metabolism to sustain contractions?
Which muscle cell type primarily utilizes aerobic metabolism to sustain contractions?
Flashcards
Excitability
Excitability
The ability of muscle cells to respond to electrical stimuli.
Contractility
Contractility
The ability of muscle cells to shorten and generate force.
Extensibility
Extensibility
The ability of muscle cells to be stretched without damage.
Elasticity
Elasticity
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Plasticity
Plasticity
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Fascicle
Fascicle
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Sarcomere
Sarcomere
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Neuromuscular Junction
Neuromuscular Junction
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Muscle Fiber
Muscle Fiber
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Myoblast
Myoblast
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Myofibril
Myofibril
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Actin
Actin
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Myosin
Myosin
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Titin
Titin
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ATPase
ATPase
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Sarcoplasmic Reticulum
Sarcoplasmic Reticulum
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Troponin
Troponin
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Myosin ATPase
Myosin ATPase
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Hydrostatic Skeleton
Hydrostatic Skeleton
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Exoskeleton
Exoskeleton
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Endoskeleton
Endoskeleton
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Study Notes
Muscle Features
- Muscles can respond to electrical stimuli (excitability)
- Muscles can shorten and create force (contractility)
- Muscles can be stretched (extensibility)
- Muscles return to their original shape after stretching or contracting (elasticity)
- Muscles adapt to length and force changes (plasticity)
Vertebrate Skeletal Muscle Organization
- Whole muscle contracts as a unit, surrounded by epimysium
- Fascicle: bundle of muscle fibers (cells), surrounded by perimysium
- Muscle fiber (cell): single muscle cell, surrounded by endomysium
- Myofibrils: thread-like structures within muscle fibers, composed of sarcomeres
- Sarcomeres: contractile units with actin (thin filaments) and myosin (thick filaments) arranged in a pattern
- Actin and myosin filaments interact to shorten sarcomeres and generate force
- Titin: protein stabilizing myosin filaments
- Tropomyosin: protein blocking actin binding sites at rest
- Troponin: protein complex moving tropomyosin, enabling contraction when calcium is present
Neuromuscular Junction Events
- Action potential travels down a motor neuron to the neuromuscular junction
- Acetylcholine (ACh) is released, binding to muscle cell membrane receptors
- Muscle cell depolarizes, generating an action potential
- Sarcoplasmic reticulum releases calcium ions (Ca2+)
- Calcium binds to troponin, causing tropomyosin to move, exposing actin binding sites
- Myosin heads bind to actin, creating cross-bridges
- Myosin undergoes a power stroke, pulling the actin filament
- ATPase activity provides the energy for the power stroke and detachment
- Sarcoplasmic reticulum pumps calcium back in, causing relaxation
Skeletal Muscle Energy Systems
- Immediate System: Uses ATP and creatine phosphate for quick energy bursts
- Glycolytic System: Anaerobic energy production from glycogen, suitable for moderate-high intensity activities
- Oxidative System: Aerobic energy production from fats, carbohydrates, and proteins, best for sustained, low intensity activities
Muscle Fiber Types
- Glycolytic (Fast Twitch) Cells: Use anaerobic metabolism, contract quickly, fatigue rapidly (e.g., sprinters, predators)
- Oxidative (Slow Twitch) Cells: Use aerobic metabolism, contract slowly, resist fatigue (e.g., long-distance runners, migratory birds)
Other Muscle Types
- Cardiac Muscle: Striated, branched, interconnected, involuntary contractions for pumping blood (heart)
- Smooth Muscle: Non-striated, spindle-shaped, involuntary contractions controlling movement in internal organs (stomach, blood vessels)
Muscle Modifications
- Asynchronous Muscle: Staggered muscle fiber contraction in insects for continuous movement (e.g., wing beats)
- Flight Muscles: Specialized muscles in birds and insects for sustained flight
- Striated Cardiac Muscle: Coordinated muscle contractions in the heart of vertebrates
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