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

Which of the following best describes an isotonic contraction?

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

What occurs during concentric isotonic contraction?

<p>Muscle shortens (B)</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. (A)</p> Signup and view all the answers

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

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

What type of muscles are arranged in antagonistic pairs?

<p>Skeletal muscles (A)</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. (B)</p> Signup and view all the answers

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

<p>Biceps Brachii (B)</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. (A)</p> Signup and view all the answers

What is the primary function of the extensor muscle?

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

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

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

What distinguishes cardiac muscle from skeletal muscle?

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

What type of connective tissue sheath surrounds each muscle?

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

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

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

During a muscle biopsy, what is primarily being analyzed?

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

What characterizes high endurance muscle?

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

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

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

What is the functional unit of skeletal muscle?

<p>Motor unit (B)</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 (B)</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. (B)</p> Signup and view all the answers

What is the refractory period in muscle physiology?

<p>0.002 sec (B)</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 (A)</p> Signup and view all the answers

What type of contraction occurs when the muscle length changes?

<p>Isotonic contraction (D)</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 (B)</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 (A)</p> Signup and view all the answers

How can summation in whole muscle occur?

<p>By increasing the number of motor units involved (C)</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 (D)</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 (B)</p> Signup and view all the answers

Where is the neuromuscular junction located?

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

What is wave summation in muscle contraction?

<p>Contractions that become superimposed upon one another (A)</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. (D)</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

Flashcards

Involuntary Muscle Type

Smooth muscle, found in organs, controls movements without conscious thought.

Tendon Function

Connects muscle to bone, enabling movement.

Muscle Origin

Fixed attachment point of a muscle during contraction.

Muscle Arrangement

Skeletal muscles often work in coordinated groups.

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Isotonic Contraction

Muscle changes length during contraction; shortening or lengthening.

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Concentric Contraction

Muscle shortens during contraction.

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Eccentric Contraction

Muscle lengthens during contraction; beneficial for muscle damage.

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Eccentric Strength

Muscle strength during eccentric contractions is approximately 10% greater than concentric contractions.

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Elbow Flexor

Biceps Brachii muscle, bends the elbow.

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Heavy Eccentric Loading

May cause greater muscle damage.

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Extensor Muscle Function

Opens a joint.

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Muscle Fiber Connection

Sarcomere connects muscle fibers, facilitating contractions.

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Cardiac Muscle vs. Skeletal Muscle

Cardiac muscle is involuntary; skeletal is voluntary.

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Muscle Covering

Epimysium is the connective tissue sheath surrounding each muscle.

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Smooth Muscle Characteristic

Does not contain intercalated discs.

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Muscle Biopsy

Analysis of histological properties of muscle tissue.

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High Endurance Muscle

Characterized by 1 centrally placed nucleus per cell.

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Frog Gastrocnemius Twitch Time

0.1 second.

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Skeletal Muscle Functional Unit

Motor unit.

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Muscle Contraction Latent Period

No visible muscle reaction to stimulus.

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Muscle All-or-None Response

Muscle contracts fully or not at all if stimulated.

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Gene Expression

Using a gene's information to create a functional product (usually a protein).

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Differential Gene Expression

Different cells express different genes, leading to different structures and functions.

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Genome Stability Factor

A factor that maintains the integrity of the genome, preventing mutations.

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Oncogene Mutations

Mutations in genes that promote uncontrolled cell growth, often in cancer.

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Tumor Suppressor Genes

Genes that regulate cell growth and division and, when mutated, allow uncontrolled cell proliferation.

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Housekeeping Genes

Essential genes for basic cellular functions, expressed in most cells.

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Rapid Mutation Accumulation

Uncontrolled cell division can lead to a quicker build-up of mutations.

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Cell Differentiation

Process by which cells become specialized in structure and function.

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Apoptosis

Programmed cell death, a controlled process crucial for development and maintenance.

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Necrosis

Traumatic cell death caused by acute injury; uncontrolled.

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Cell Differentiation

The process by which cells become specialized in structure and function.

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Unipotent cells

Cells that can only differentiate into one specific cell type.

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Pluripotent Cells

Cells that can differentiate into many different cell types.

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Mitochondria in Apoptosis

Mitochondria play a key role in triggering the process of apoptosis (programmed cell death).

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Cell Death Triggers

Factors that can induce cell death include genetic mutations, damage, stress, or signals from other cells.

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Mesenchymal cells

Stem cells capable of differentiating into various connective and muscle tissues (bone, cartilage etc).

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Stem Cell

An undifferentiated cell that self-renews and can become more stem cells or differentiated cells.

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Potency

The ability of a stem cell to differentiate into different cell types.

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Totipotent

Stem cells capable of forming any cell type in the body and extraembryonic tissues.

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Pluripotent

Stem cells that can form any cell type in the body, but not extraembryonic tissues.

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Multipotent

Stem cells that can form a limited number of cell types.

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Unipotent

Stem cells that can only differentiate into one specific cell type.

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Differentiation

The process where cells become specialized in structure and function.

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Cell Determination

The progressive fixation of a cell's descendants' fate.

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DNA Packaging

The process of organizing DNA within cells to fit tightly into the nucleus. Involves concepts like Heterochromatin and Euchromatin.

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Dolly the Sheep

A sheep cloned using a mammary gland cell and an enucleated egg, demonstrating the possibility of cloning using differentiated cells.

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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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