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Questions and Answers
What is one function of the muscular system related to maintaining the body's structure?
What is one function of the muscular system related to maintaining the body's structure?
What characteristic allows muscles to respond to stimulation from motor neurons?
What characteristic allows muscles to respond to stimulation from motor neurons?
How are skeletal muscles primarily identified?
How are skeletal muscles primarily identified?
What is the functional unit of a muscle fiber called?
What is the functional unit of a muscle fiber called?
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During muscle contraction, what is the role of ATP?
During muscle contraction, what is the role of ATP?
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What identifies the origin of a muscle?
What identifies the origin of a muscle?
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What is one role of synergist muscles during contraction?
What is one role of synergist muscles during contraction?
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What happens to muscle fibers when they do not receive enough ATP?
What happens to muscle fibers when they do not receive enough ATP?
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What structure covers a whole muscle?
What structure covers a whole muscle?
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What is the primary function of the antagonist muscle?
What is the primary function of the antagonist muscle?
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Which muscle tissue type is primarily responsible for involuntary contractions?
Which muscle tissue type is primarily responsible for involuntary contractions?
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Which characteristic allows muscles to return to their original length after being stretched?
Which characteristic allows muscles to return to their original length after being stretched?
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What is primarily affected during muscle fatigue due to strenuous exercise?
What is primarily affected during muscle fatigue due to strenuous exercise?
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What is produced as a byproduct of anaerobic respiration in muscles?
What is produced as a byproduct of anaerobic respiration in muscles?
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Study Notes
Functions of the Muscular System
- Muscles produce movement, including locomotion, facial expressions, blood circulation, peristalsis (food passage), and ventilation. Leg muscles regulate blood flow as an example.
- Muscles maintain posture and stabilize joints, reinforcing bone connections via tendons.
- Muscles generate heat through cellular respiration, crucial in maintaining body temperature.
Muscle Characteristics
- Excitability: Respond to stimuli (neurons or hormones).
- Contractility: Shorten when stimulated.
- Extensibility: Lengthen beyond original state.
- Elasticity: Return to original length/shape.
Types of Muscle Tissues
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Skeletal Muscle:
- Cylindrical, striated, multinucleated.
- Voluntarily controlled.
- Contracts quickly or slowly.
- Attached to bones.
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Cardiac Muscle:
- Branched, striated, uninucleated.
- Involuntarily controlled.
- Mostly contracts slowly and steadily, except during activity.
- Found in the heart.
-
Smooth Muscle:
- Arranged in layers, non-striated, uninucleated.
- Involuntarily controlled.
- Mostly slow, sustained contractions.
- Found in internal organs (e.g., stomach).
Microscopic Muscle Structure
- Muscle: Bundles of fibers, attached to bones by tendons.
- Fascicle: Bundles within muscles.
- Muscle Fiber: Long, thin cells, with sarcoplasmic reticulum (impulse transmission).
- Myofibril: Thread-like organelles, organized in sarcomeres (striated units).
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Myofilaments:
- Actin (thin)
- Myosin (thick)
- Form the sliding filament model, driving contraction.
Muscle Protection (Sheaths)
- Epimysium: Covers the entire muscle.
- Perimysium: Covers a fascicle (bundle of fibers).
- Endomysium: Covers individual muscle fibers.
Myofilament Arrangement
- Actin and myosin filaments are arranged between Z-lines.
- The space between Z-lines is a sarcomere.
- Myofilament interaction shortens the sarcomere.
Muscle Fiber Contraction
- Nerve impulses initiate contraction.
- Myosin heads attach to actin, pulling it (requires ATP & Ca2+).
- Z-lines move closer, shortening the sarcomere.
- This (sliding filament theory) repeats until contraction is complete.
Role of ATP in Muscle Contraction
- Muscle is either contracted or relaxed.
- Contraction strength depends on the engaged fibers.
- Each myosin-actin interaction uses 1 ATP molecule.
- ATP production requires cellular respiration (food & oxygen).
- Insufficient ATP leads to muscle fatigue.
Muscle Fatigue and Oxygen Debt
- Intense exercise exhausts glucose, leading to fatigue.
- Myosin heads cannot attach to actin filaments.
- Anaerobic respiration (burning) occurs.
- Lactate (fuel source) prevents immediate muscle failure.
- Lactate threshold – when lactate can no longer prevent failure.
- Delayed Onset Muscle Soreness (DOMS) is pain days later.
- Oxygen debt - difference in oxygen required and available.
Muscle Attachment to Skeleton
- Muscles attach to bones via tendons.
- Origin: Less movable attachment point (usually closer to midline).
- Insertion: More movable attachment point (usually farther from midline).
- Belly: Middle of the muscle.
- Muscles work in pairs: Prime mover (agonist), synergists (assist), antagonist (opposes).
Synergists and Muscle Interactions
- Muscles work together for coordinated movements.
- Prime Mover (Agonist): Primary muscle for a movement.
- Synergists: Help the agonist, add force, stabilize joints.
- Antagonist: Opposes the agonist, prevents excessive movement and injury.
- Synergists are essential for smooth, precise movement, stability, and reducing strain.
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Description
Explore the essential functions and characteristics of the muscular system through this quiz. Learn about muscle types, their roles in movement, and properties such as excitability and contractility. Test your knowledge on how muscles maintain posture and generate heat.
