Week 4
48 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

How does the stretch-shortening cycle enhance performance?

  • It increases the number of cross-bridge formations leading to increased force production.
  • It shifts the force-velocity curve to the left, enabling greater force output at any velocity.
  • It decreases the velocity of contraction, leading to faster force development.
  • It utilizes the stored elastic energy from passive tension and activates the stretch reflex. (correct)
  • What is the relationship between muscle shortening velocity and force production?

  • As shortening velocity increases, force production decreases. (correct)
  • Shortening velocity only affects force production in the eccentric phase.
  • As shortening velocity increases, force production also increases.
  • Shortening velocity has no impact on force production.
  • Which type of muscle contraction occurs when the muscle is lengthening?

  • Flexion contraction
  • Eccentric contraction (correct)
  • Concentric contraction
  • Isometric contraction
  • What is the relationship between muscle power, force, and velocity?

    <p>Power is equal to the product of force and velocity. (C)</p> Signup and view all the answers

    At what velocity does maximum power output occur?

    <p>Approximately half of maximum velocity and one third of maximum concentric force (A)</p> Signup and view all the answers

    What is the main factor contributing to increased force production during eccentric contraction?

    <p>Passive elements like Titin (A)</p> Signup and view all the answers

    How does the angle of muscle pull affect muscle tension?

    <p>It determines the maximum tension that can be developed during a single contraction. (B)</p> Signup and view all the answers

    What is the primary benefit of a preparatory counter movement before a jump?

    <p>It increases the number of cross-bridge formations for greater force. (B)</p> Signup and view all the answers

    Which type of muscle is found in the walls of hollow organs and operates under involuntary control?

    <p>Smooth muscle (C)</p> Signup and view all the answers

    What is a key feature of cardiac muscle tissue?

    <p>It allows for synchronized contraction. (D)</p> Signup and view all the answers

    Which of the following is NOT a function of skeletal muscle?

    <p>Transport oxygen in the blood (D)</p> Signup and view all the answers

    What is one criteria used to name muscles based on their structure?

    <p>Action (D)</p> Signup and view all the answers

    Which muscle is primarily involved in breathing?

    <p>Diaphragm (B)</p> Signup and view all the answers

    Which muscle characteristic refers to its shape, such as triangular or wide?

    <p>Shape (C)</p> Signup and view all the answers

    What role do myokines play in skeletal muscle function?

    <p>They have hormone-like effects. (D)</p> Signup and view all the answers

    Skeletal muscle contributes to which of the following functions?

    <p>Joint stabilization (A)</p> Signup and view all the answers

    Which type of muscle fibers are not inter-convertible through physical training?

    <p>Slow twitch fibers (A), Fast twitch fibers (D)</p> Signup and view all the answers

    What is the primary contributor to a person's muscle fiber distribution?

    <p>Genetic factors (B)</p> Signup and view all the answers

    How does a muscle increase its force production?

    <p>By activating more motor units (A)</p> Signup and view all the answers

    What occurs when many action potentials travel down a motor neuron axon faster than the twitch response time?

    <p>A summation of mechanical force response (A)</p> Signup and view all the answers

    Which motor unit is recruited first during light to moderate efforts?

    <p>Slow twitch motor units (D)</p> Signup and view all the answers

    What happens at high firing rates of motor neurons?

    <p>The muscle is maximally activated (B)</p> Signup and view all the answers

    What is the optimal length for muscle contraction related to?

    <p>The maximum number of cross-bridge formations (C)</p> Signup and view all the answers

    Which of the following best describes the recruitment of motor units as force requirements increase?

    <p>Motor units with progressively larger axons are recruited (D)</p> Signup and view all the answers

    What is the primary function of skeletal muscle?

    <p>To attach to and move the skeleton (D)</p> Signup and view all the answers

    What is the composition of skeletal muscle tissue?

    <p>75% water, 20% protein, and various inorganic salts and fats (C)</p> Signup and view all the answers

    Which type of muscle is characterized as being under voluntary control?

    <p>Skeletal muscle (A)</p> Signup and view all the answers

    What property distinguishes muscle cells, allowing them to shrink and develop tension?

    <p>Contractility (D)</p> Signup and view all the answers

    Which statement accurately describes the structural characteristics of skeletal muscle?

    <p>It has a striated pattern due to organized contractile molecules. (D)</p> Signup and view all the answers

    How does the size principle relate to motor units?

    <p>Motor units are recruited in order of increasing size for force generation. (C)</p> Signup and view all the answers

    Which factor does NOT influence muscle force production?

    <p>Nutritional intake prior to exercise (A)</p> Signup and view all the answers

    In what way do skeletal, smooth, and cardiac muscle functionally differ?

    <p>Only skeletal muscle is striated. (C)</p> Signup and view all the answers

    Which muscle is an example of a bipennate muscle?

    <p>rectus femoris (A)</p> Signup and view all the answers

    What term describes the muscle that is primarily responsible for a particular movement?

    <p>Prime mover (C)</p> Signup and view all the answers

    Which of the following muscle names indicates its size?

    <p>gluteus maximus (B)</p> Signup and view all the answers

    Which type of muscle architecture consists of fasciculi that run parallel to the long axis of the muscle?

    <p>Longitudinal (A)</p> Signup and view all the answers

    What is the role of fixator muscles during movement?

    <p>To stabilize joints (A)</p> Signup and view all the answers

    Which of the following describes a muscle whose fibers fan out from a single attachment?

    <p>Radiate (B)</p> Signup and view all the answers

    Which of the following pairs of muscles are antagonists?

    <p>triceps brachii and biceps brachii (A)</p> Signup and view all the answers

    Which of the following correctly identifies the meaning of the prefix 'tri' in 'triceps brachii'?

    <p>three (D)</p> Signup and view all the answers

    What is the primary function of the axon of a motor neuron?

    <p>To transmit action potentials to target muscles. (A)</p> Signup and view all the answers

    Which type of muscle fibers are also classified as type IIa?

    <p>Fast twitch oxidative-glycolytic fibers (C)</p> Signup and view all the answers

    How many muscle fibers does an average motor unit innervate?

    <p>About 200 fibers (A)</p> Signup and view all the answers

    In terms of fiber type distribution, how do endurance athletes differ from power athletes?

    <p>Endurance athletes possess higher slow twitch muscle fiber proportions. (A)</p> Signup and view all the answers

    What law dictates that motor units either fire fully or not at all?

    <p>The all-or-none law (C)</p> Signup and view all the answers

    What percentage of slow twitch fibers do men, women, and children have in their arm and leg muscles on average?

    <p>45 to 55% (A)</p> Signup and view all the answers

    Which structure is responsible for innervating multiple muscle fibers within a motor unit?

    <p>The axon and its bifurcations (C)</p> Signup and view all the answers

    What is the primary method used to determine muscle fiber type proportions in humans?

    <p>Muscle biopsy technique (A)</p> Signup and view all the answers

    Flashcards

    Skeletal Muscle Function

    Involves cross-bridge cycling, force generation, and mechanical influence.

    Three Muscle Types

    Skeletal, smooth, and cardiac; each has unique structure and function.

    Skeletal Muscle Composition

    About 75% water, 20% protein, and rest is salts, pigments, fats, carbohydrates.

    Striated Muscle

    Skeletal muscle has a striped appearance due to organized contractile molecules.

    Signup and view all the flashcards

    Voluntary Control

    Skeletal muscle is operated consciously and controlled by the nervous system.

    Signup and view all the flashcards

    Motor Unit

    A motor neuron and the muscle fibers it controls; responsible for muscle contraction.

    Signup and view all the flashcards

    Force Control of a Motor Unit

    Describes how muscle force is regulated, including the size principle.

    Signup and view all the flashcards

    Muscle Architecture

    Refers to the arrangement of muscle fibers affecting functional differences.

    Signup and view all the flashcards

    Smooth muscle

    Involuntary muscle found in hollow organs and blood vessels. It has non-aligned contractile molecules, leading to a smooth appearance.

    Signup and view all the flashcards

    Cardiac muscle

    Muscle tissue of the heart; has characteristics of both smooth and skeletal muscle with organized striations and involuntary control.

    Signup and view all the flashcards

    Functions of Skeletal Muscle

    1. Produce movement 2. Maintain posture 3. Aid in breathing 4. Stabilize joints 5. Support tissues 6. Generate heat 7. Guard entrances 8. Support chewing and talking.
    Signup and view all the flashcards

    Muscle Naming Criteria

    Criteria for naming muscles include shape, action, location, division, size relationships, and fiber direction.

    Signup and view all the flashcards

    Myokines

    Signaling proteins released by skeletal muscles that have hormone-like effects, influencing various body functions.

    Signup and view all the flashcards

    Adductor Magnus

    A muscle that brings limbs closer to the body. It’s an example of a muscle named for its action.

    Signup and view all the flashcards

    Skeletal muscle structure

    composed of long, cylindrical fibers; supports contraction and movement through organized layers and blood supply.

    Signup and view all the flashcards

    Biceps Brachii

    A muscle with two heads located in the upper arm, responsible for elbow flexion.

    Signup and view all the flashcards

    Triceps Brachii

    A muscle with three heads located in the upper arm, responsible for elbow extension.

    Signup and view all the flashcards

    Quadriceps Femoris

    A muscle group consisting of four heads located in the thigh, crucial for knee extension.

    Signup and view all the flashcards

    Antagonist Muscle

    A muscle that opposes the action of another muscle, often located on opposite sides of a joint.

    Signup and view all the flashcards

    Prime Mover

    A muscle primarily responsible for a specific movement, often leading the action.

    Signup and view all the flashcards

    Fixators/Stabilizers

    Muscles that stabilize a joint to allow the prime mover to operate efficiently.

    Signup and view all the flashcards

    Unipennate Muscle

    Muscle where all fasciculi insert on one side of the tendon, e.g., semimembranosus.

    Signup and view all the flashcards

    Radiate (Convergent) Muscle

    Muscle fibers that fan out from a single attachment point, e.g., pectoralis major.

    Signup and view all the flashcards

    Types of Muscle Fibers

    Muscle fibers categorized as slow twitch, fast twitch, FOG, and FG based on function and characteristics.

    Signup and view all the flashcards

    Inter-conversion of Fibers

    FOG and FG fibers can be changed through training, while slow and fast twitch fibers cannot.

    Signup and view all the flashcards

    Multiples of Motor Unit Recruitment

    Increasing force production by activating more motor units in larger muscles, up to 2,000 units.

    Signup and view all the flashcards

    Twitch vs. Summation

    A twitch occurs with a single action potential, while summation increases force with multiple potentials.

    Signup and view all the flashcards

    Tetanus in Muscle Contraction

    High firing rates of motor neurons result in maximally activated muscle, producing up to 5x the twitch force.

    Signup and view all the flashcards

    Size Principle of Recruitment

    As force needs increase, larger axons and motor units are recruited for stronger contractions.

    Signup and view all the flashcards

    Length-Tension Relationship

    Optimal muscle length allows for maximum cross-bridge formation, affecting force production.

    Signup and view all the flashcards

    Muscle Length-Tension Relationship

    The relationship between muscle length and the force it can produce, showing optimal length for maximum force.

    Signup and view all the flashcards

    Stretch-Shortening Cycle

    A rapid stretching followed by a shortening of muscle that enhances performance in activities like jumping.

    Signup and view all the flashcards

    Force-Velocity Relationship

    It describes how a muscle's force output changes with the speed of contraction.

    Signup and view all the flashcards

    Concentric Contraction

    Muscle shortening as it contracts, producing positive velocity.

    Signup and view all the flashcards

    Eccentric Contraction

    Muscle lengthening while under tension, producing more force at higher speeds.

    Signup and view all the flashcards

    Isometric Contraction

    Muscle remains constant in length while generating tension, no movement occurs.

    Signup and view all the flashcards

    Power-Velocity Relationship

    Power is the product of force and velocity; maximum power occurs at submaximal force and velocity.

    Signup and view all the flashcards

    Angle of Muscle Pull

    The angle at which a muscle pulls on a bone, influencing tension production during contraction.

    Signup and view all the flashcards

    Motor Neuron Cell Body

    The part of a motor neuron located in the spinal cord.

    Signup and view all the flashcards

    Bifurcation of Axon

    The splitting of an axon into multiple branches to innervate muscle fibers.

    Signup and view all the flashcards

    Action Potential

    An electrical signal generated by a strong enough stimulus in a motor neuron.

    Signup and view all the flashcards

    All-or-None Law

    If a neuron fires, it stimulates all muscle fibers in the motor unit fully or not at all.

    Signup and view all the flashcards

    Slow Twitch Fibers

    Muscle fibers that contract slowly and rely on oxygen for energy.

    Signup and view all the flashcards

    Fast Twitch Fibers

    Muscle fibers that contract quickly, suited for short bursts of strength or speed.

    Signup and view all the flashcards

    Muscle Fiber Type Distribution

    Variation of muscle fiber types across individuals and different muscles.

    Signup and view all the flashcards

    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,.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    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.

    More Like This

    Skeletal Muscle Anatomy and Physiology
    18 questions
    Introduction to Skeletal Muscle Anatomy
    93 questions
    Anatomy of Skeletal Muscle
    53 questions
    Muscle Anatomy and Physiology Quiz
    39 questions

    Muscle Anatomy and Physiology Quiz

    SelfRespectThunderstorm9253 avatar
    SelfRespectThunderstorm9253
    Use Quizgecko on...
    Browser
    Browser