Muscle Physiology Quiz
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Questions and Answers

What is a motor unit composed of?

  • Muscle fibers and blood vessels
  • Only muscle fibers
  • A motor neuron and muscle fibers (correct)
  • Multiple motor neurons

    • The number of muscle fibers in a motor unit can be several hundred.

    True

    What are the two primary proteins involved in muscular contraction?

    Actin and Myosin

    A motor unit consists of a motor neuron and the __________ it innervates.

    <p>muscle fibers</p> Signup and view all the answers

    Match the following components of the motor unit with their functions:

    <p>Motor Neuron = Sends impulses to muscle fibers Muscle Fibers = Contract in response to stimulation Neuromuscular Junction = Site of impulse transmission Myelin Sheath = Insulates the motor neuron</p> Signup and view all the answers

    Which of the following videos explains how a nervous impulse initiates a muscle contraction?

    <p>How Do Nervous Impulses Cause Muscle to Contract?</p> Signup and view all the answers

    The Sliding Filament Theory describes the act of muscle contraction through the interaction of actin and myosin.

    <p>True</p> Signup and view all the answers

    What physiological principle maintains a constant volume in a contracting muscle?

    <p>Isometric contraction</p> Signup and view all the answers

    What happens to the distance between actin and myosin filaments when a muscle shortens?

    <p>It increases.</p> Signup and view all the answers

    Type I muscle fibers are classified as fast fibers.

    <p>False</p> Signup and view all the answers

    What are the two primary categories of muscle fibers based on speed of contraction?

    <p>Type I and Type II</p> Signup and view all the answers

    Myosin ATPase rates are _____ in fast muscle fibers compared to slow muscle fibers.

    <p>2-3 times greater</p> Signup and view all the answers

    Match the muscle fiber types with their corresponding characteristics:

    <p>Type I = Slow-twitch, red appearance Type II = Fast-twitch, white appearance Type IIA = Intermediate speed, some fatigue resistance Type IIB = Fast-twitch, low endurance</p> Signup and view all the answers

    Which of the following methods is NOT used for muscle fiber typing?

    <p>Electromyography</p> Signup and view all the answers

    Myosin heavy chains are the motor protein of the thick muscle filaments.

    <p>True</p> Signup and view all the answers

    Name one histochemical technique used to identify muscle fibers.

    <p>Myosin ATPase staining</p> Signup and view all the answers

    What does an increase in SEMG amplitude represent?

    <p>Increased efferent motor output</p> Signup and view all the answers

    Hypertrophy can be detected after only one week of training.

    <p>False</p> Signup and view all the answers

    What is the purpose of Transcranial Magnetic Stimulation (TMS)?

    <p>To stimulate underlying neurones in the primary motor cortex.</p> Signup and view all the answers

    The measure that represents overall efferent motor output of the alpha-motorneurone pool is called a ______.

    <p>V-wave</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>H-reflex = Evaluates spinal alpha-motorneurone excitability MEP = Measure of corticospinal excitability Silent period = Measure of corticospinal inhibition Voluntary activation = Magnitude of efferent drive to muscle</p> Signup and view all the answers

    What happens to the silent period duration with resistance training?

    <p>Decreases</p> Signup and view all the answers

    What does the twitch interpolation method help determine?

    <p>The level of voluntary activation.</p> Signup and view all the answers

    Resistance training has no effect on H-reflex at rest or during maximal voluntary contraction.

    <p>True</p> Signup and view all the answers

    Which of the following muscle fiber types is classified as slow twitch?

    <p>Type I</p> Signup and view all the answers

    Type IIa fibers have a higher aerobic capacity than Type IIx fibers.

    <p>True</p> Signup and view all the answers

    What are the two main categories of muscle contraction?

    <p>Isotonic and Isometric</p> Signup and view all the answers

    Type IIa and IIx fibers are primarily known for their _____ production capacity.

    <p>force</p> Signup and view all the answers

    Match the following fiber types with their characteristics:

    <p>Type I = High capacity for aerobic energy supply Type IIa = Fast twitch, fatigable Type IIx = Low aerobic power Type IIB = Unidentified in humans</p> Signup and view all the answers

    Which term describes a contraction where the muscle length does not change?

    <p>Isometric</p> Signup and view all the answers

    Humans express the fastest MHC isoform of MHCIIb.

    <p>False</p> Signup and view all the answers

    What morphological adaptation is characterized by an increase in muscle cross-sectional area?

    <p>Hypertrophy</p> Signup and view all the answers

    What is the primary role of hormones in the body?

    <p>To co-ordinate and regulate physiological and metabolic functions</p> Signup and view all the answers

    Chronic endocrine adaptations result in a reduction of heart rate and blood pressure to a given workload.

    <p>True</p> Signup and view all the answers

    Name two hormones that contribute to acute endocrine responses.

    <p>Testosterone and Cortisol</p> Signup and view all the answers

    The process of moving away from the mid-line of the body is called __________.

    <p>abduction</p> Signup and view all the answers

    Match the following types of muscle actions with their definitions:

    <p>Agonist = Muscle that contracts to produce a movement Antagonist = Muscle that opposes the action of the agonist Synergist = Muscle that assists the agonist in performing an action Stabiliser = Muscle that helps maintain posture during movement</p> Signup and view all the answers

    Which training parameter is crucial for causing adaptations in tendons and ligaments?

    <p>High-intensity training</p> Signup and view all the answers

    Spotting is not necessary for overhead movements during weight training.

    <p>False</p> Signup and view all the answers

    What is the recommended action during a sticking point in weightlifting?

    <p>Exhale</p> Signup and view all the answers

    A group of repetitions is known as a __________.

    <p>set</p> Signup and view all the answers

    Which of the following best describes the Valsalva maneuver?

    <p>A breathing method to increase abdominal pressure</p> Signup and view all the answers

    Grip width does not affect lifting potential.

    <p>False</p> Signup and view all the answers

    What is the primary influence of range of motion on weightlifting?

    <p>It influences the load that can be lifted.</p> Signup and view all the answers

    The maximum load that can be lifted for a specified number of repetitions is known as the __________.

    <p>repetition maximum (RM)</p> Signup and view all the answers

    Match the following intensity categories with their respective rep ranges:

    <p>Very high intensity = 1-4 reps High intensity = 4-8 reps Moderate intensity = 8-12 reps Low intensity = 12-20 reps</p> Signup and view all the answers

    Study Notes

    Skeletal Muscle Motor Unit

    • A motor unit is comprised of a motor neuron and the muscle fibers it innervates.
    • Typically hundreds of fibres are contained within a motor unit.

    Microscopic Structure of Muscle

    • Actin and myosin are proteins that make up the structure of muscle fibres.
    • Actin is the thin filament and myosin is the thick filament.
    • Actin and myosin slide past each other during a muscle contraction, shortening the sarcomere (the functional unit of a muscle fibre).

    Muscle Contraction

    • Occurs when a nervous impulse causes the release of calcium ions from the sarcoplasmic reticulum.
    • Calcium ions bind to troponin, which moves tropomyosin out of the way, allowing myosin to bind to actin.
    • ATP is required for the myosin head to detach from actin and re-attach, powering the sliding filament mechanism.

    Fibre Types

    • Type I muscle fibres are slow twitch, fatigue resistant, and have a high capacity for aerobic energy supply.
    • Type IIa and IIx muscle fibres are fast twitch and fatigable, with a limited aerobic capacity.
    • Type IIa fibres have a higher aerobic capacity than Type IIx fibres.

    Contraction Types

    • Isoinertial contractions involve a constant external mass.
    • Concentric contractions involve shortening of the muscle.
    • Eccentric contractions involve lengthening of the muscle.
    • Isometric contractions involve no change in muscle length or joint angle.
    • Isokinetic contractions involve a constant angular velocity.

    Resistance Training Adaptations

    • Resistance training (RT) leads to increases in muscle hypertrophy, strength, power, and strength endurance.
    • Morphological adaptations are changes in the physical structure of the muscle.
    • Neural adaptations refer to changes in the nervous system that improve motor unit recruitment, firing rate, and synchronization.
    • Endocrine adaptations involve changes in the production and secretion of hormones.

    Morphological Adaptations - Hypertrophy

    • Hypertrophy is an increase in muscle cross-sectional area.
    • Hypertrophy occurs due to increased synthesis and decreased degradation of contractile proteins.
    • Increased number of myofibrils within each fibre as well as fibre splitting (hyperplasia).

    Neural Adaptations

    • Improvements in strength can occur before hypertrophy is observed.
    • Increased muscle activation is a key neural adaptation.
    • RT can also enhance corticospinal excitability, reduce silent period duration, and increase voluntary activation.

    Endocrine Adaptations

    • RT can lead to changes in the secretion of testosterone, growth hormone, cortisol, and insulin-like growth factor 1 (IGF-1).
    • The volume and intensity of training are important factors in determining the endocrine response.

    Cardiovascular Adaptations

    • RT can lead to increased heart rate, stroke volume, cardiac output, and ventilation rate during acute exercise.
    • Chronic adaptations include no change in resting heart rate or blood pressure, increased ventricular wall thickness, and reduced heart rate and blood pressure at a given absolute workload.

    Other Tissue Adaptations

    • RT can improve bone mineral density, tendon, ligament, and fascia strength.
    • High intensity training is required to cause significant changes in these tissues.

    Terminology

    • Repetitions (Reps): one complete cycle of a movement from the start to the end of range and return.
    • Set: a group of repetitions.
    • Rest: passive time between sets.
    • Repetition maximum (RM): the maximum load that can be lifted for a specified number of repetitions.
    • Intensity: the amount of weight lifted, can be expressed as absolute weight or as a percentage of an RM.
    • Volume: a measure of the total work performed, often calculated as sets x reps x load lifted.

    Movements and Muscles

    • Agonist/Antagonist: muscles that work together to produce a movement.
    • Prime Mover/Synergist/Stabilizer: different roles muscles can have during a movement.
    • Flexion: decreasing the angle at a joint.
    • Extension: increasing the angle at a joint.
    • Adduction: moving towards the midline.
    • Abduction: moving away from the midline.

    Gym Etiquette and Safety

    • Hygiene: Maintain cleanliness in the gym environment.
    • Clothing and Footwear: Choose appropriate attire for safe and effective training.
    • Sharing equipment: Be respectful of others using equipment.
    • Exercise technique: Focus on proper form to avoid injury.
    • Spotting: Have a partner help with potentially dangerous lifts.
    • Use of collars: Help to prevent plates from sliding off the barbell.
    • Weight selection: Choose appropriate weight that allows for good technique.
    • Equipment maintenance: Report any damages to the facility.
    • Floor layout and other hazards: Be aware of the surrounding environment.

    Breathing

    • Generally exhale through the sticking point (transition from eccentric to concentric phase) of a lift.
    • Valalva manoeuvre (holding breath) can be used during maximal effort lifts.

    Weight Belts

    • Provide external support for abdominal muscles.
    • Can be helpful in some circumstances, but not necessary for all lifts.

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    EXSC216 Resistance Training: Science & Application – Introduction 2020 PDF

    Description

    Test your understanding of muscle physiology, including the structure and function of motor units, muscle contraction mechanisms, and different muscle fiber types. This quiz covers key concepts such as actin and myosin interaction, and the role of calcium ions in muscle contraction.

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