Muscle Anatomy and Functions Quiz
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Questions and Answers

Which type of muscle is primarily responsible for involuntary movement within organs?

  • Smooth muscle (correct)
  • Skeletal muscle
  • Cardiac muscle
  • Striated muscle

    • What is the primary role of tendons in the musculoskeletal system?

  • Connect muscle to bone (correct)
  • Allow for muscle contraction
  • Support joint stability
  • Attach muscle to muscle

    • Which component is typically the fixed attachment point of a muscle during contraction?

  • Tendon
  • Insertion
  • Joint
  • Origin (correct)

    • How are skeletal muscles primarily arranged in the body?

    <p>They often work in coordinated groups.</p> Signup and view all the answers

    Which of the following best describes an isotonic contraction?

    <p>Muscle shortens or lengthens during contraction.</p> Signup and view all the answers

    What occurs during concentric isotonic contraction?

    <p>Muscle shortens</p> Signup and view all the answers

    Which of the following statements is true about eccentric contractions?

    <p>They are beneficial for increasing muscle damage.</p> Signup and view all the answers

    What is a key characteristic of muscle during eccentric isotonic contraction?

    <p>The muscle lengthens</p> Signup and view all the answers

    What type of muscles are arranged in antagonistic pairs?

    <p>Skeletal muscles</p> Signup and view all the answers

    How does the strength of muscles during eccentric contractions compare to concentric contractions?

    <p>Muscles are approximately 10% stronger during eccentric contractions.</p> Signup and view all the answers

    Which muscle is responsible for flexing the arm at the elbow?

    <p>Biceps Brachii</p> Signup and view all the answers

    What effect does heavy eccentric loading have on muscles?

    <p>It may cause greater muscle damage when overloaded.</p> Signup and view all the answers

    What is the primary function of the extensor muscle?

    <p>Opens a joint</p> Signup and view all the answers

    What connects the muscle fibers within each muscle to facilitate contractions?

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

    What distinguishes cardiac muscle from skeletal muscle?

    <p>Cardiac muscle is involuntary</p> Signup and view all the answers

    What type of connective tissue sheath surrounds each muscle?

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

    Which of the following is NOT a characteristic of smooth muscle?

    <p>Contains intercalated discs</p> Signup and view all the answers

    During a muscle biopsy, what is primarily being analyzed?

    <p>Histological properties of muscle tissue</p> Signup and view all the answers

    What characterizes high endurance muscle?

    <p>1 centrally placed nucleus per cell</p> Signup and view all the answers

    What is the duration of the twitch response in the frog gastrocnemius muscle?

    <p>0.1 sec</p> Signup and view all the answers

    What is the functional unit of skeletal muscle?

    <p>Motor unit</p> Signup and view all the answers

    Which describes the all-or-nothing response of muscle contraction?

    <p>Contraction occurs only if the neuron stimulates the muscle fibre</p> Signup and view all the answers

    What occurs during the latent period of muscle contraction?

    <p>There is no visible reaction to the stimulus.</p> Signup and view all the answers

    What is the refractory period in muscle physiology?

    <p>0.002 sec</p> Signup and view all the answers

    What is true about motor units and dexterity?

    <p>Fewer muscle fibres per motor unit lead to increased dexterity</p> Signup and view all the answers

    What type of contraction occurs when the muscle length changes?

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

    What phenomenon occurs when stimulation at a frequency shorter than the twitch time results in the second stimulus being superimposed on the first?

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

    What role does asynchronous firing of motor units play during muscle contraction?

    <p>It ensures smooth, graded responses</p> Signup and view all the answers

    How can summation in whole muscle occur?

    <p>By increasing the number of motor units involved</p> Signup and view all the answers

    At what frequency do the twitches begin to fuse together in a state of maximal contraction called tetanus?

    <p>40 pulses/sec</p> Signup and view all the answers

    What is the average number of muscle fibres per motor unit in the human body?

    <p>150 fibres/MU</p> Signup and view all the answers

    Where is the neuromuscular junction located?

    <p>Between the motor neuron and muscle fibre</p> Signup and view all the answers

    What is wave summation in muscle contraction?

    <p>Contractions that become superimposed upon one another</p> Signup and view all the answers

    What role does asynchronous firing of motor units play during muscle contraction?

    <p>It contributes to both motor unit summation and wave summation.</p> Signup and view all the answers

    What role do oncogenes and tumor suppressor genes play in cancer development?

    <p>Oncogenes promote cell growth and division when mutated, while tumor suppressor genes, when lost or nonfunctional, fail to regulate the cell cycle, leading to uncontrolled cell proliferation.</p> Signup and view all the answers

    How does differential gene expression contribute to cell specialization?

    <p>Differential gene expression allows specific genes to be activated or silenced, leading to the unique structure and function of specialized cells like neurons and osteocytes.</p> Signup and view all the answers

    What are housekeeping genes and why are they essential?

    <p>Housekeeping genes are genes that are expressed in all cell types to maintain basic cellular functions such as metabolism and DNA repair.</p> Signup and view all the answers

    How can external factors influence gene expression in cells?

    <p>External factors such as environmental signals or nutrition can modify gene expression, leading to changes in cell behavior and function.</p> Signup and view all the answers

    What is the significance of stem cell potency in developmental biology?

    <p>Stem cell potency refers to the varying potential of stem cells to differentiate into different cell types, ranging from totipotent to pluripotent.</p> Signup and view all the answers

    In what ways can epigenetics impact cellular fate decisions?

    <p>Epigenetic modifications can alter gene expression without changing the DNA sequence, influencing cell fate by determining which genes are turned on or off.</p> Signup and view all the answers

    What is the relationship between cellular responses and the micro-environment?

    <p>Cells respond to signals from their micro-environment, which can affect gene expression and trigger specific cellular responses crucial for adaptation and survival.</p> Signup and view all the answers

    How do mutations in DNA repair mechanisms contribute to genome instability?

    <p>Mutations that inactivate DNA repair mechanisms can lead to an accumulation of DNA damage, resulting in genome instability and increased cancer risk.</p> Signup and view all the answers

    What is apoptosis and how does it differ from necrosis?

    <p>Apoptosis is programmed cell death that is a controlled process, while necrosis is traumatic cell death resulting from acute injury.</p> Signup and view all the answers

    Define pluripotent stem cells and give an example.

    <p>Pluripotent stem cells can differentiate into almost any cell type in the body; an example is embryonic stem cells.</p> Signup and view all the answers

    Explain the role of mitochondria in apoptosis.

    <p>Mitochondria regulate apoptosis by releasing factors like cytochrome c, which activate apoptosomes and lead to cell death.</p> Signup and view all the answers

    What are mesenchymal cells and their significance in tissue formation?

    <p>Mesenchymal cells are multipotent stem cells that can differentiate into various cell types, including muscle and connective tissue.</p> Signup and view all the answers

    Differentiate between adult and embryonic stem cells in terms of potency.

    <p>Adult stem cells are typically multipotent, capable of differentiating into a limited range of cell types, while embryonic stem cells are pluripotent.</p> Signup and view all the answers

    How can the cellular micro-environment influence cell differentiation?

    <p>The cellular micro-environment provides chemical signals and physical cues that can activate specific signaling pathways, guiding cell differentiation.</p> Signup and view all the answers

    What is the significance of gene expression regulation in apoptosis?

    <p>Gene expression regulation is crucial in apoptosis as it determines which pro-apoptotic or anti-apoptotic genes are activated, influencing cell survival.</p> Signup and view all the answers

    Discuss an ethical issue involved in stem cell research.

    <p>One ethical issue is the moral status of embryos used for deriving embryonic stem cells, raising concerns about their destruction.</p> Signup and view all the answers

    What is the difference between totipotent and pluripotent stem cells?

    <p>Totipotent stem cells can differentiate into any cell type in the body and extra embryological tissues, while pluripotent stem cells can differentiate into any cell type but not extra embryological tissues.</p> Signup and view all the answers

    How does cell differentiation progress from stem cells to specialized cells?

    <p>Cell differentiation involves a progressive commitment to a specific cell fate, leading to the maturation of stem cells into specialized, functional cells.</p> Signup and view all the answers

    What role does the micro-environment play in stem cell determination?

    <p>The micro-environment provides mechanical, chemical, and physical cues that influence the fate and behavior of stem cells during determination and differentiation.</p> Signup and view all the answers

    Define epigenetics in the context of cell fate determination.

    <p>Epigenetics refers to heritable changes in gene expression that do not involve alterations to the underlying DNA sequence, impacting how cells differentiate and commit to specific lineages.</p> Signup and view all the answers

    What is the final step in the process of cell differentiation?

    <p>The final step in cell differentiation is cell specialization, where a cell adopts a specific function and structure, marking the point of irreversible commitment.</p> Signup and view all the answers

    How does lineage commitment affect the potential of a stem cell?

    <p>Lineage commitment restricts a stem cell's differentiation potential, gradually fixing its fate toward a more limited range of cell types as development progresses.</p> Signup and view all the answers

    Explain the significance of heterochromatin and euchromatin in gene expression.

    <p>Heterochromatin is tightly packed, leading to gene silencing, while euchromatin is loosely packed, allowing for active gene expression.</p> Signup and view all the answers

    What processes are involved in the progressive fixation of a cell's fate?

    <p>The progressive fixation of a cell's fate involves genetic commitment and epigenetic regulation, enabling cells to restrict their developmental pathways over time.</p> Signup and view all the answers

    Discuss the impact of soluble factors on stem cell differentiation.

    <p>Soluble factors, such as growth factors and cytokines, provide essential signals that guide stem cells toward specific differentiation pathways.</p> Signup and view all the answers

    Study Notes

    Musculoskeletal System, Nervous System & Bioelectricity

    • The lecture covers the musculoskeletal system, nervous system, and bioelectricity, focusing on muscle anatomy and physiology.
    • The lecturer is Dr. Tom Hodgkinson.

    Learning Outcomes

    • Students will be able to discuss the three main muscle types (cardiac, smooth, and striated).
    • Students will be able to describe the structure and arrangement of anatomical muscles.
    • Students will be able to outline the innervation of the motor unit.
    • Students will be able to describe the physiology of whole muscle action, including twitch and summation.
    • Students will be able to differentiate between isometric and isotonic contraction.

    Muscle Types

    • Muscles are the body's movement tissues.
    • Some muscles are voluntary, others involuntary.
    • Three main muscle types: skeletal, cardiac, and smooth.
      • Skeletal muscles are attached to bones.
      • Cardiac muscles are found in the myocardium.
      • Smooth muscles are found in organs.

    Skeletal Muscle

    • About 40% of the body composition is skeletal muscle.
    • Approximately 650 skeletal muscles exist in the human body.
    • More than 150 surface (anatomical) muscles are present.

    Skeletal Muscle and Associated Tissues

    • Muscle: Tissue capable of contraction.
    • Tendon: Fibrous connective tissue linking muscle to bone.
    • Ligament: Connects bones to bones.

    Skeletal Muscle Attachments

    • Skeletal muscles typically connect to two bones across a joint.
    • The attachment point that remains stationary is the origin.
    • The moving attachment is the insertion.
    • Muscle action occurs as the insertion is drawn toward the origin.

    Skeletal Muscle (Arm)

    • Biceps brachii: Muscle that flexes the arm at the elbow.
    • Triceps brachii: Extends the arm at the elbow.
    • Muscle action is often more complex than simple flexion or extension.
      • Multiple muscles are often involved in movements.

    Skeletal Muscle Structure

    • Muscles composed of millions of muscle fibers.

    • Fibers extend the entire length of the muscle.

    • Epimysium: A layer of connective tissue surrounding the entire muscle.

    • Fascicles: Bundles of muscle fibers encased in perimysium.

    • Muscle fiber (cell): Encased in endomysium.

    • Myofibrils: Smaller fibers within muscle fibers.

    • Sarcomeres: Contractile units within myofibrils.

      • Contain actin and myosin filaments.

    Skeletal Muscle Analysis

    • Muscle biopsy: A procedure to remove muscle tissue.
    • Histological stains: Techniques used to analyze the tissue.
    • Longitudinal and cross sections can be used for analysis.

    Cardiac Muscle

    • Found only in the heart.
    • Involuntary, high-endurance muscle.
    • Striated with intercalated disks (gap junctions).
    • 1-2 nuclei per cell, centrally placed.
    • Innervated by the pacemaker.

    Smooth Muscle

    • Lines digestive tract, trachea, and blood vessels.
    • Involuntary.
    • High endurance.
    • One nucleus per cell.
    • No striations.
    • Sustained contractions.

    Motor Unit

    • The functional unit of skeletal muscle.
    • Composed of a single motor neuron and the associated muscle fibers it innervates.
    • Some motor neurons must innervate more than one fiber.
    • The number of muscle fibers/motor unit varies based on the required precision of the movement.
      • Fewer fibers = greater dexterity.

    Motor Unit (Neuromuscular Junction)

    • Neuromuscular junction (NMJ): The connection between nerve and muscle fibers.
    • NMJ enables close contact between nerve and muscle cells.
    • One NMJ per muscle fiber.
    • Stimulation of the NMJ leads to muscle contraction (all-or-nothing response).

    Motor Unit (Muscle Contraction)

    • Whole-muscle contraction: Result of the number of stimulated motor units.
    • Maximal contraction: When all motor units are active.
    • Graded response: Asynchronous firing of motor units to produce smooth, non-jerky movement.

    Types of Muscle Contraction

    • Isometric contraction: Muscle length stays constant, but tension increases.

    • Isotonic contraction: Muscle length changes, but tension remains constant.

      • Concentric: Muscle shortens.
      • Eccentric: Muscle lengthens.

    Muscle Physiology Twitch and Summation

    • Twitch: Muscle response to a single electrical stimulus.

    • Summation: Muscle response to subsequent stimuli before the previous one has fully relaxed.

      • Multiple motor units: Increasing motor unit involvement to increase force.
      • Wave summation: Increasing stimulation rate—resulting in a greater shortening.

    Muscle Physiology- Tetanization

    • Tetanization: Rapid stimulation rate—leading to sustained muscle contraction.

    • Maximal force is generated during tetanus.

    • Further increasing stimulation during tetanus results in marginally more shortening.

    References

    • Textbook resources listed.

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    Description

    Test your knowledge on muscle anatomy, types, and functions. This quiz covers questions about involuntary movements, muscle contractions, and more. Perfect for students studying biology or health sciences.

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