Muscle Contractions and Movement Quiz
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Questions and Answers

What type of contraction is performed to produce the desired movement?

  • Eccentric contraction
  • Isometric contraction
  • Concentric contraction (correct)
  • Passive contraction

    • What is primarily expended during a concentric contraction?

  • Oxygen
  • Energy (correct)
  • Lactic acid
  • Calcium

    • Which of the following best describes the role of concentric contraction in movement?

  • It lengthens the muscle to ease tension.
  • It stabilizes joints without producing movement.
  • It prevents movement while energy is conserved.
  • It produces movement while doing most of the work. (correct)

    • In what phase does a muscle exert the most effort during a concentric contraction?

    <p>Contraction phase</p> Signup and view all the answers

    What movement characteristic is least associated with concentric contractions?

    <p>Creating stability in the joint</p> Signup and view all the answers

    What role do synergists play in a movement?

    <p>They assist the prime mover during the movement.</p> Signup and view all the answers

    What is one effect of muscle tone mentioned in the content?

    <p>It aids in teeth alignment through the lips.</p> Signup and view all the answers

    Which statement best describes muscle tone?

    <p>It can have important effects even as a gentle force.</p> Signup and view all the answers

    Which of the following is NOT typically associated with synergists?

    <p>They only function when the prime mover is inactive.</p> Signup and view all the answers

    Why is muscle tone considered important?

    <p>It helps maintain proper alignment in various body parts.</p> Signup and view all the answers

    What role do the rotator cuff muscles play during a bicep curl?

    <p>They serve as fixators for shoulder stabilization.</p> Signup and view all the answers

    Where are the majority of fixator muscles located in the body?

    <p>Around the hip and shoulder joints.</p> Signup and view all the answers

    What is a common basis for naming most skeletal muscles?

    <p>Their function or the bones they attach to</p> Signup and view all the answers

    Which characteristic is primarily associated with fixator muscles?

    <p>They stabilize a joint to allow for movement of another muscle.</p> Signup and view all the answers

    Which of the following correctly identifies a muscle based on its name?

    <p>Trapezius, named for its trapezoidal shape</p> Signup and view all the answers

    In the context of physical exercises, what is the primary function of the rotator cuff?

    <p>To maintain stability of the shoulder joint during various movements.</p> Signup and view all the answers

    What does the term 'sternocleidomastoid' indicate about this particular muscle?

    <p>It is named after its specific points of attachment</p> Signup and view all the answers

    What is a common misunderstanding regarding the fixator muscles?

    <p>They initiate the movement of the limbs.</p> Signup and view all the answers

    Why might a muscle be named after a certain function?

    <p>To highlight its contribution to movement or stabilization</p> Signup and view all the answers

    What is the importance of naming muscles based on their attachment points?

    <p>It aids in the understanding of muscle actions and interactions</p> Signup and view all the answers

    What is the primary issue with new fibers produced after major muscle degeneration?

    <p>They do not compensate for muscle loss effectively.</p> Signup and view all the answers

    What characterizes the composition of new skeletal muscle after trauma?

    <p>Disorganized mixture of muscle fibers and scar tissue.</p> Signup and view all the answers

    What happens to the ability of new fibers to regenerate muscle effectively after trauma?

    <p>They are unable to regenerate effectively.</p> Signup and view all the answers

    What type of tissue is found interspersed with new muscle fibers after trauma?

    <p>Fibrous scar tissue.</p> Signup and view all the answers

    Which statement best describes the nature of muscle regeneration following major muscle degeneration?

    <p>Most of the regenerated tissue involves scar formation.</p> Signup and view all the answers

    What primarily causes skeletal muscles to grow larger?

    <p>Frequent strenuous exercise</p> Signup and view all the answers

    Which activity is most associated with the enlargement of skeletal muscles?

    <p>Body building</p> Signup and view all the answers

    What is NOT a factor influencing the growth of skeletal muscle?

    <p>Use of over-the-counter pain medication</p> Signup and view all the answers

    Which statement is true about skeletal muscle growth?

    <p>Skeletal muscles grow larger in response to strenuous exercise.</p> Signup and view all the answers

    What is the primary physiological response of skeletal muscle to consistent strenuous exercise?

    <p>Hypertrophy or muscle enlargement</p> Signup and view all the answers

    Study Notes

    Introduction to Human Anatomy 7101101

    • Course name: Introduction to Human Anatomy
    • Course code: 7101101

    Lectures 10 and 11: Muscular System (4 hours)

    • Topic: Muscular System
    • Duration: 4 hours

    Muscle Types

    • Three types are described based on characteristics:
      • Voluntary or involuntary control
      • Appearance under microscope (striated or smooth)
      • Location (body wall, limbs, or hollow organs/blood vessels)
    • Types of muscles:
      • Skeletal striated muscle
      • Cardiac striated muscle
      • Smooth muscle

    Cardiac Striated Muscle

    • Involuntary visceral muscle
    • Forms most of the heart walls
    • Adjacent parts of great vessels (e.g., aorta)
    • Pumps blood
    • Cells branch and anastomose
    • Transverse striations
    • Intercalated discs
    • Single, central nucleus
    • Strong, quick, and continuous rhythmic contraction
    • Involuntary, intrinsically (myogenically) stimulated and propagated
    • Modified by autonomic nervous system

    Smooth Muscle

    • Involuntary visceral muscle
    • Forms walls of most vessels and hollow organs
    • Moves substances by coordinated sequential contractions (pulsations or peristaltic contractions)
    • Cells are single and spindle-shaped
    • Lack striations
    • Single, central nucleus
    • Weak, slow, rhythmic, or sustained tonic contractions
    • Involuntary, autonomic nervous system

    Skeletal Muscles

    • Voluntary somatic muscle
    • Forms most of the named muscles
    • Composed of skeletal striated muscle
    • Organs of locomotion
    • Provide static support
    • Help give form to the body
    • Produces heat through shivering

    Skeletal Muscle Structure

    • Have fleshy, reddish, contractile portions (one or more heads or bellies)
    • Some have white non-contractile portions (tendons) composed of collagen bundles
    • Provide attachment
    • Tendons are included when measuring muscle length

    Myofibril Structure

    • Rod-like units
    • Composed of actin, myosin, and other proteins
    • Organized into thick (myosin) and thin (actin) filaments
    • Filaments repeat along the lengths of the myofibril
    • Contract by sliding filaments

    Muscle Fiber Structure

    • Cylindrical, multinucleate
    • Comprised of numerous myofibrils
    • Enclosed by endomysium
    • Muscle fascicles are bundles of muscle fibers
    • Surrounded by perimysium
    • Muscle is a group of fascicles
    • Enclosed by epimysium (deep fascia)

    Muscle Attachment

    • Most skeletal muscles are attached directly or indirectly to bones, cartilages, ligaments, or fascias.
    • Some muscles attach to organs (like eyeballs), skin, or mucous membranes (like the tongue).
    • Tendons of some muscles can appear as flat sheets (aponeuroses)
    • Tendons attach muscles to a ridge and/or series of spinous processes; deep fascia.
    • They may also attach to another muscle's aponeurosis.

    Muscle Names

    • Most muscles are named on the basis of their function or the bones to which they're attached.
    • Examples include abductor digiti minimi, sternocleidomastoid.

    Muscle Functional Types

    • Prime mover (agonist): The main muscle responsible for a specific movement.
    • Antagonist: A muscle that opposes the action of another muscle.
    • Fixator: Stabilizes the origin of the agonist and/or the joint to aid the agonist movement.
    • Synergist: Assists the prime mover, often providing a weaker or less mechanically advantaged component of the movement

    Muscle Contraction

    • Isometric Contraction: Muscle length stays the same, but tension increases. Important for maintaining posture or resisting gravity
    • Isotonic Contraction: Muscle length changes during movement.
      • Concentric: Muscle shortens.
      • Eccentric: Muscle lengthens.

    Reflexive Contraction

    • Skeletal muscles are also reflexive.
    • The myotatic reflex (stretch reflex) produces movement after tapping a tendon.
    • The respiratory movements are often reflexively controlled by carbon dioxide and oxygen levels in blood.

    Tonic Contraction

    • Even when relaxed, muscles of a conscious individual are slightly contracted (muscle tone).
    • Muscle tone helps maintain posture and joint stability
    • Usually absent in unconscious individuals (e.g., during deep sleep, or under general anesthesia), or after nerve damage

    Motor Unit

    • Functional unit of a muscle
    • Consists of a motor neuron and its associated muscle fibers
    • When stimulated, all the muscle fibers contract simultaneously.
    • Fiber number varies according to muscle size and function

    Muscle Growth & Regeneration

    • Skeletal muscle fibers cannot divide but can be replaced by newer fibers
    • Derived from satellite cells.
    • New fibers are insufficient for major muscle regeneration after degeneration/trauma
    • New fiber growth/repair takes place with fibrous scar tissue
    • Hypertrophy is increase in size of existing fibers.

    Cardiac Muscle

    • Forms parts of the myocardium, aorta walls, pulmonary veins, and superior vena cava
    • Involuntary contractions
    • Heart rate intrinsically regulated by pacemaker
    • Impulse-conducting system and autonomic nervous system (ANS)
    • Striated appearance under microscopy
    • Rapid and strong contractions

    Smooth Muscle Growth & Hypertrophy

    • Smooth muscle cells respond to increased demands by undergoing compensatory hypertrophy
    • Smooth muscle cells may also increase in number (hyperplasia) in pregnancy, in the uterine wall for example.
    • New smooth muscle cells develop from pericytes along small blood vessels.

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    Lecture 10 and 11 Muscular System PDF

    Description

    Test your knowledge on the types of muscle contractions, their roles, and muscle tone. This quiz covers important concepts related to movement mechanics and the functions of various muscle groups. Perfect for students looking to deepen their understanding of anatomy and physiology.

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