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Questions and Answers
How does the stretch-shortening cycle enhance performance?
How does the stretch-shortening cycle enhance performance?
What is the relationship between muscle shortening velocity and force production?
What is the relationship between muscle shortening velocity and force production?
Which type of muscle contraction occurs when the muscle is lengthening?
Which type of muscle contraction occurs when the muscle is lengthening?
What is the relationship between muscle power, force, and velocity?
What is the relationship between muscle power, force, and velocity?
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At what velocity does maximum power output occur?
At what velocity does maximum power output occur?
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What is the main factor contributing to increased force production during eccentric contraction?
What is the main factor contributing to increased force production during eccentric contraction?
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How does the angle of muscle pull affect muscle tension?
How does the angle of muscle pull affect muscle tension?
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What is the primary benefit of a preparatory counter movement before a jump?
What is the primary benefit of a preparatory counter movement before a jump?
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Which type of muscle is found in the walls of hollow organs and operates under involuntary control?
Which type of muscle is found in the walls of hollow organs and operates under involuntary control?
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What is a key feature of cardiac muscle tissue?
What is a key feature of cardiac muscle tissue?
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Which of the following is NOT a function of skeletal muscle?
Which of the following is NOT a function of skeletal muscle?
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What is one criteria used to name muscles based on their structure?
What is one criteria used to name muscles based on their structure?
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Which muscle is primarily involved in breathing?
Which muscle is primarily involved in breathing?
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Which muscle characteristic refers to its shape, such as triangular or wide?
Which muscle characteristic refers to its shape, such as triangular or wide?
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What role do myokines play in skeletal muscle function?
What role do myokines play in skeletal muscle function?
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Skeletal muscle contributes to which of the following functions?
Skeletal muscle contributes to which of the following functions?
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Which type of muscle fibers are not inter-convertible through physical training?
Which type of muscle fibers are not inter-convertible through physical training?
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What is the primary contributor to a person's muscle fiber distribution?
What is the primary contributor to a person's muscle fiber distribution?
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How does a muscle increase its force production?
How does a muscle increase its force production?
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What occurs when many action potentials travel down a motor neuron axon faster than the twitch response time?
What occurs when many action potentials travel down a motor neuron axon faster than the twitch response time?
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Which motor unit is recruited first during light to moderate efforts?
Which motor unit is recruited first during light to moderate efforts?
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What happens at high firing rates of motor neurons?
What happens at high firing rates of motor neurons?
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What is the optimal length for muscle contraction related to?
What is the optimal length for muscle contraction related to?
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Which of the following best describes the recruitment of motor units as force requirements increase?
Which of the following best describes the recruitment of motor units as force requirements increase?
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What is the primary function of skeletal muscle?
What is the primary function of skeletal muscle?
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What is the composition of skeletal muscle tissue?
What is the composition of skeletal muscle tissue?
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Which type of muscle is characterized as being under voluntary control?
Which type of muscle is characterized as being under voluntary control?
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What property distinguishes muscle cells, allowing them to shrink and develop tension?
What property distinguishes muscle cells, allowing them to shrink and develop tension?
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Which statement accurately describes the structural characteristics of skeletal muscle?
Which statement accurately describes the structural characteristics of skeletal muscle?
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How does the size principle relate to motor units?
How does the size principle relate to motor units?
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Which factor does NOT influence muscle force production?
Which factor does NOT influence muscle force production?
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In what way do skeletal, smooth, and cardiac muscle functionally differ?
In what way do skeletal, smooth, and cardiac muscle functionally differ?
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Which muscle is an example of a bipennate muscle?
Which muscle is an example of a bipennate muscle?
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What term describes the muscle that is primarily responsible for a particular movement?
What term describes the muscle that is primarily responsible for a particular movement?
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Which of the following muscle names indicates its size?
Which of the following muscle names indicates its size?
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Which type of muscle architecture consists of fasciculi that run parallel to the long axis of the muscle?
Which type of muscle architecture consists of fasciculi that run parallel to the long axis of the muscle?
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What is the role of fixator muscles during movement?
What is the role of fixator muscles during movement?
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Which of the following describes a muscle whose fibers fan out from a single attachment?
Which of the following describes a muscle whose fibers fan out from a single attachment?
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Which of the following pairs of muscles are antagonists?
Which of the following pairs of muscles are antagonists?
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Which of the following correctly identifies the meaning of the prefix 'tri' in 'triceps brachii'?
Which of the following correctly identifies the meaning of the prefix 'tri' in 'triceps brachii'?
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What is the primary function of the axon of a motor neuron?
What is the primary function of the axon of a motor neuron?
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Which type of muscle fibers are also classified as type IIa?
Which type of muscle fibers are also classified as type IIa?
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How many muscle fibers does an average motor unit innervate?
How many muscle fibers does an average motor unit innervate?
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In terms of fiber type distribution, how do endurance athletes differ from power athletes?
In terms of fiber type distribution, how do endurance athletes differ from power athletes?
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What law dictates that motor units either fire fully or not at all?
What law dictates that motor units either fire fully or not at all?
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What percentage of slow twitch fibers do men, women, and children have in their arm and leg muscles on average?
What percentage of slow twitch fibers do men, women, and children have in their arm and leg muscles on average?
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Which structure is responsible for innervating multiple muscle fibers within a motor unit?
Which structure is responsible for innervating multiple muscle fibers within a motor unit?
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What is the primary method used to determine muscle fiber type proportions in humans?
What is the primary method used to determine muscle fiber type proportions in humans?
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Flashcards
Skeletal Muscle Function
Skeletal Muscle Function
Involves cross-bridge cycling, force generation, and mechanical influence.
Three Muscle Types
Three Muscle Types
Skeletal, smooth, and cardiac; each has unique structure and function.
Skeletal Muscle Composition
Skeletal Muscle Composition
About 75% water, 20% protein, and rest is salts, pigments, fats, carbohydrates.
Striated Muscle
Striated Muscle
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Voluntary Control
Voluntary Control
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Motor Unit
Motor Unit
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Force Control of a Motor Unit
Force Control of a Motor Unit
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Muscle Architecture
Muscle Architecture
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Smooth muscle
Smooth muscle
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Cardiac muscle
Cardiac muscle
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Functions of Skeletal Muscle
Functions of Skeletal Muscle
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Muscle Naming Criteria
Muscle Naming Criteria
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Myokines
Myokines
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Adductor Magnus
Adductor Magnus
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Skeletal muscle structure
Skeletal muscle structure
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Biceps Brachii
Biceps Brachii
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Triceps Brachii
Triceps Brachii
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Quadriceps Femoris
Quadriceps Femoris
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Antagonist Muscle
Antagonist Muscle
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Prime Mover
Prime Mover
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Fixators/Stabilizers
Fixators/Stabilizers
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Unipennate Muscle
Unipennate Muscle
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Radiate (Convergent) Muscle
Radiate (Convergent) Muscle
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Types of Muscle Fibers
Types of Muscle Fibers
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Inter-conversion of Fibers
Inter-conversion of Fibers
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Multiples of Motor Unit Recruitment
Multiples of Motor Unit Recruitment
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Twitch vs. Summation
Twitch vs. Summation
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Tetanus in Muscle Contraction
Tetanus in Muscle Contraction
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Size Principle of Recruitment
Size Principle of Recruitment
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Length-Tension Relationship
Length-Tension Relationship
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Muscle Length-Tension Relationship
Muscle Length-Tension Relationship
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Stretch-Shortening Cycle
Stretch-Shortening Cycle
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Force-Velocity Relationship
Force-Velocity Relationship
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Concentric Contraction
Concentric Contraction
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Eccentric Contraction
Eccentric Contraction
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Isometric Contraction
Isometric Contraction
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Power-Velocity Relationship
Power-Velocity Relationship
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Angle of Muscle Pull
Angle of Muscle Pull
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Motor Neuron Cell Body
Motor Neuron Cell Body
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Bifurcation of Axon
Bifurcation of Axon
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Action Potential
Action Potential
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All-or-None Law
All-or-None Law
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Slow Twitch Fibers
Slow Twitch Fibers
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Fast Twitch Fibers
Fast Twitch Fibers
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Muscle Fiber Type Distribution
Muscle Fiber Type Distribution
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Study Notes
Introduction to Biomedical Physiology and Kinesiology - Skeletal Muscle
- Skeletal muscle comprises approximately 36% of total body weight in women and 42% in men.
- 75% of skeletal muscle is water, 20% is protein.
- The remainder is inorganic salts (K+, Cl-), pigments, and fats/carbohydrates.
- Myology is the scientific study of muscle.
- Muscle cells (fibers) are the only cells in the body with contractility, enabling them to shorten and develop tension.
Skeletal Muscle Structure
- Gross Anatomy:
- Origin: Less movable end of a muscle, usually proximal.
- Insertion: More movable end of a muscle, usually distal.
- Belly: Widest portion of the muscle, situated between the origin and insertion.
- Connective Tissue:
- Tendons: Extensions of connective tissue beyond the muscle end; transmit contractile force to bone.
- Important connective tissue layers enveloping the muscle include epimysium, perimysium, and endomysium.
- Tendons are stronger than muscle and can handle large force from multiple muscle fibers, inserting onto small bone areas (e.g., tuberosities).
- Microanatomy:
- Muscle cells are muscle fibers.
- Myofibrils within muscle fibers.
- Myofibrils consist of repeating contractile protein arrays: sarcomeres
- Sarcomeres are the functional units of muscle. They're defined by Z-lines.
- Two major contractile proteins are actin (thin filaments) and myosin (thick filaments).
- The sliding filament theory describes muscle contraction.
- Myosin forms cross bridges to actin, causing the sarcomeres to shorten.
Skeletal Muscle Function
-
Motor Units: Clusters of muscle fibers innervated by a single motor neuron.
- A neuron can innervate a range of 2-2000 muscle fibers.
-
Types of Motor Units: Classified based on speed of contraction and metabolic characteristics. These are primarily type I (slow twitch, oxidative), type IIa (fast-twitch, oxidative-glycolytic), and type IIx (fast-twitch, glycolytic).
- Each muscle fiber type has unique characteristics in terms of speed of contraction, fatigue resistance, and metabolic profile.
-
Force Control of a Motor Unit:
- Summation: Increasing the number of activated motor units (multiple motor unit summation) or increasing the rate of stimulation (frequency or wave summation) increases force output.
- Size Principle: Motor units are recruited in a size-order manner, starting with smaller units for smaller force and progressively larger units with greater force requirements.
-
Mechanical Factors influencing Muscle Force Production:
- Muscle Length-Tension Relationship: Optimal sarcomere length for maximum force generation. Too much shortening or lengthening will lead to reduced force.
- Muscle Force-Velocity Relationship: Maximum force is generated at zero shortening velocity (isometric contracts). Maximal power output occurs at approximately one half of maximum velocity and one third of the maximum concentric force.
- Angle of Muscle Pull: Muscle pulling at 90 degrees to the bone to rotate optimally. Force decreases as the angle diverges from this optimal angle,.
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Description
This quiz covers key concepts related to skeletal muscle physiology and structure. It delves into myology, the composition of skeletal muscle, and the gross anatomy including origins, insertions, and connective tissues. Test your knowledge on the important elements that make up skeletal muscles and their functionality.