Muscle Tissue Properties Quiz

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Questions and Answers

Which property of muscular tissue allows it to respond to stimuli by generating electrical signals?

  • Electrical activity (correct)
  • Contractility
  • Elasticity
  • Extensibility

What characteristic is unique to skeletal muscle tissue?

  • Ability to stretch
  • Ability to contract
  • Ability to return to its original shape
  • Presence of striations (correct)

Which function of muscular tissue is most directly involved in maintaining body temperature in cold conditions?

  • Storing and moving substances
  • Producing body movements
  • Generating heat (correct)
  • Stabilizing body position

A weightlifter strains to lift a heavy barbell. Which property of muscle tissue is primarily being tested during this activity?

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

After a muscle is stretched, it recoils to its original length. What property allows this to happen?

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

What is the primary function of muscle tissue?

<p>To generate force using ATP (C)</p> Signup and view all the answers

All of the following are types of muscle tissue EXCEPT:

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

Which type of muscle tissue is primarily responsible for voluntary movements?

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

What is the main role of ATP in muscle function?

<p>To provide energy for force generation (A)</p> Signup and view all the answers

What is the defining characteristic of all muscle tissues?

<p>They all contain elongated cells called muscle fibers or myocytes (D)</p> Signup and view all the answers

In terms of location, where would you expect to find smooth muscle?

<p>In the walls of blood vessels and digestive tract (A)</p> Signup and view all the answers

Which of the following best describes the cellular structure of muscle tissue?

<p>Elongated cells capable of contraction (D)</p> Signup and view all the answers

Which type of muscle tissue is responsible for the rhythmic contractions of the heart?

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

Which characteristic is unique to cardiac muscle compared to both skeletal and smooth muscle?

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

Which connective tissue layer directly surrounds individual muscle fibers?

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

What is the primary function of involuntary muscle contractions described in the content?

<p>Constriction of blood vessels and propulsion of food (B)</p> Signup and view all the answers

Considering their functions, where would you MOST likely find smooth muscle?

<p>Wall of the small intestine (C)</p> Signup and view all the answers

If a muscle is described as being encircled by a dense irregular connective tissue, which layer is being referenced?

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

How does skeletal muscle differ structurally from both cardiac and smooth muscle?

<p>It contains multinucleated cells. (D)</p> Signup and view all the answers

What type of tissue primarily forms a tendon?

<p>Dense regular connective tissue (A)</p> Signup and view all the answers

Which type of muscle tissue relies primarily on somatic motor neurons for its activation?

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

Which of the following is a key function of skeletal muscle?

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

Which of the following structures is formed by the perimysium?

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

Which system(s) control involuntary muscle function?

<p>Endocrine and autonomic nervous systems (D)</p> Signup and view all the answers

What structural adaptation in cardiac muscle facilitates rapid communication between cells, allowing the heart to function as a coordinated unit?

<p>Intercalated discs with gap junctions (C)</p> Signup and view all the answers

Which of the following is NOT a location of smooth muscle tissue?

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

What would happen if the endomysium surrounding a muscle fiber was damaged?

<p>The muscle fiber might not receive enough nutrients or eliminate waste efficiently. (D)</p> Signup and view all the answers

The calcaneal tendon (Achilles tendon) connects which muscle to the calcaneus (heel bone)?

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

How do cardiac and smooth muscle control differ from skeletal muscle control?

<p>Cardiac and smooth muscles are controlled involuntarily. (D)</p> Signup and view all the answers

Which of the following is the primary role of structural proteins within muscle tissue?

<p>Maintaining alignment of filaments and linking myofibrils. (B)</p> Signup and view all the answers

Titin is a structural protein important for which of the following muscle characteristics?

<p>Providing elasticity and extensibility to myofibrils. (D)</p> Signup and view all the answers

During muscle contraction, what specific action does the myosin head perform?

<p>It binds to actin, forming a cross-bridge. (B)</p> Signup and view all the answers

If a drug interferes with the function of nebulin, which aspect of muscle structure would be most directly affected?

<p>The alignment and structural integrity of thin filaments. (C)</p> Signup and view all the answers

Which protein directly enables the transfer of force from the myofibrils to the extracellular matrix?

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

What is the primary role of the sarcoplasmic reticulum in a relaxed muscle cell?

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

What is the functional significance of T-tubules in muscle cells?

<p>Carrying the action potential from the sarcolemma to the cell interior. (A)</p> Signup and view all the answers

What structural component is formed by a single T-tubule and two terminal cisternae?

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

What defines a sarcomere?

<p>The functional unit of skeletal muscle responsible for contraction. (A)</p> Signup and view all the answers

Which type of muscle protein generates force during muscle contraction?

<p>Contractile proteins. (C)</p> Signup and view all the answers

Actin and myosin directly contribute to which aspect of muscle function?

<p>Generating the sliding force for muscle contraction. (C)</p> Signup and view all the answers

How do transverse tubules contribute to the process of muscle contraction?

<p>By rapidly conducting action potentials to the interior of the muscle fiber. (B)</p> Signup and view all the answers

Troponin and tropomyosin have what key function in muscle contraction?

<p>Regulating the on and off switch of the contraction process. (D)</p> Signup and view all the answers

Flashcards

Muscle Functions

The primary roles of muscles include movement, stabilization, substance transport, and heat generation.

Electrical Activity

The ability of muscular tissue to generate electrical signals in response to stimuli, known as action potentials.

Contractility

The muscular tissue's capability to contract forcefully when stimulated by an action potential.

Extensibility

The ability of muscular tissue to stretch without being damaged, within certain limits.

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Elasticity

The property of muscular tissue to return to its original length and shape after being stretched or contracted.

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Muscular Tissue

Tissue composed of elongated cells (muscle fibers) that contract to produce force.

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Types of Muscle Tissue

The three types are skeletal, cardiac, and smooth muscle, each with distinct functions and structures.

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Skeletal Muscle

Striated muscle attached to bones for voluntary movement; made of long fibers.

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Cardiac Muscle

Striated muscle found in the heart, involuntary, responsible for pumping blood.

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Smooth Muscle

Involuntary muscle found in walls of organs; not striated, controls automatic movements.

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Tendons

Connective tissues that attach muscles to bones, aiding in movement.

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Aponeuroses

Broad, flat connective tissue sheets attaching muscles to each other or to bones.

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Muscle Fiber Components

Skeletal muscle fibers consist of myofibrils, which contain myofilaments (actin and myosin).

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Structural Proteins

Proteins that maintain the alignment of filaments and provide elasticity to myofibrils.

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Titin

A structural protein that helps maintain the elasticity and alignment of thick filaments in muscles.

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Contractile Proteins

Proteins responsible for generating force during muscle contractions, primarily myosin and actin.

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Myosin

A thick filament contractile protein that forms the main component of muscle fibers and has a tail and two heads.

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Actin

A contractile protein that is the primary component of thin filaments, has a binding site for myosin heads.

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Muscle Fiber

A multinucleated cell with striated bands, attached to bones.

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Striated Muscle

Muscle with alternating light and dark protein bands, primarily skeletal muscle.

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Intercalated Discs

Thickened regions in cardiac muscle that connect cells and allow rapid communication.

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Autorhythmic

Characteristic of cardiac muscle to initiate its own contractions without nerve signals.

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Involuntary Muscle Control

Muscle control not consciously directed, includes cardiac and smooth muscle.

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Calcium Ion Storage

Calcium ions are stored in relaxed muscles, essential for contraction.

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Calcium Ion Release

Release of calcium ions triggers muscle contraction during movement.

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Transverse Tubules (T-tubules)

Extensive network that carries electrical signals into muscle cells.

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Triad Structure

A triad consists of one T-tubule and two terminal cisternae.

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Sarcomere

The functional unit of skeletal muscle, composed of thick and thin filaments.

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Regulatory Proteins

Proteins such as troponin and tropomyosin that regulate muscle contraction.

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Myofibrils Composition

Myofibrils are built from contractile and regulatory proteins important for muscle function.

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Involuntary Muscle Contraction

Powerful, involuntary contractions for motion, controlled by endocrine and autonomic system.

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Epimysium

The outermost connective tissue layer encircling the entire muscle, made of dense irregular tissue.

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Perimysium

Dense connective tissue surrounding groups of muscle fibers, forming bundles called fascicles.

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Endomysium

A delicate tissue layer with reticular fibers, separating individual muscle fibers within a fascicle.

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Fascicles

Bundles of muscle fibers grouped by perimysium, can contain 10-100 or more fibers.

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Calcaneal Tendon

A specific tendon (Achilles) connecting the gastrocnemius muscle to the heel bone.

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Connective Tissue Sheaths

Layers of tissue (epimysium, perimysium, endomysium) that organize muscle structure.

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Study Notes

Muscle Physiology I

  • Muscular tissue consists of elongated cells called muscle fibers or myocytes that generate force using ATP.
  • Muscle tissue types include skeletal, cardiac, and smooth.
  • Functions of muscle tissue include producing body movements, stabilizing body position, storing and moving substances within the body, and generating heat.

Properties of Muscular Tissue

  • Electrical activity: The ability of muscle tissue to respond to stimuli by producing electrical signals (action potentials).
  • Contractility: The ability of muscle tissue to contract forcefully when stimulated by an action potential.
  • Extensibility: The ability of muscle tissue to stretch, within limits, without being damaged.
  • Elasticity: The ability of muscle tissue to return to its original length and shape after contraction or extension.

Skeletal Muscle

  • Description: Long, cylindrical, striated fibers with multiple nuclei at the periphery.
  • Striated: Alternating light and dark protein bands visible under a microscope.
  • Location: Attached to bones.
  • Function: Locomotion, facial expressions, posture, respiratory movements, other body movements, and heat production.
  • Control: Voluntary (somatic), controlled by somatic motor neurons.
  • Composition: 40% of body weight.

Cardiac Muscle

  • Description: Branched, striated fibers with usually only one centrally located nucleus. Connected by intercalated discs (desmosomes and gap junctions).
  • Location: Heart.
  • Function: Pumps blood to all parts of the body.
  • Control: Involuntary, controlled by the endocrine and autonomic nervous systems.
  • Characteristic: Autorhythmic (capable of generating its own electrical impulses).

Smooth Muscle

  • Description: Nonstriated fibers; spindle-shaped cells with a single, centrally located nucleus. Abundant gap junctions.
  • Location: Iris of the eyes, walls of hollow internal structures like blood vessels, airways, stomach, intestines, gallbladder, urinary bladder, and uterus.
  • Function: Involuntary powerful contractions that cause motion (e.g., constriction of blood vessels, propulsion of food).
  • Control: Involuntary, controlled by the endocrine and autonomic nervous systems.

Connective Tissue Sheaths of Skeletal Muscle

  • Epimysium: Outer layer, surrounds the entire muscle, dense irregular connective tissue.
  • Perimysium: Connective tissue layer surrounding groups of 10-100 (or more) muscle fibers, separating them into bundles called fascicles.
  • Endomysium: Reticular fibers penetrating the interior of each fascicle; separating individual muscle fibers from each other.

Tendon

  • A cord of dense, regular connective tissue formed by the three layers of connective tissue sheaths of the skeletal muscle.
  • Attaches the muscle to the periosteum of a bone.
  • Examples: Calcaneal tendon (Achilles), tendons of the gastrocnemius muscle.

Aponeurosis

  • A tendon that extends as a broad, flat layer.
  • Example: external oblique aponeurosis.

Microscopic Anatomy of a Skeletal Muscle Fiber

  • Sarcoplasm: Muscle cell cytoplasm. Contains myoglobin (binds oxygen).
  • T tubules: Tiny invaginations of the sarcolemma (plasma membrane). Quickly spread the muscle action potential to all parts of the muscle fiber.
  • Sarcoplasmic reticulum: Smooth endoplasmic reticulum. Forms an irregular curtain around fibrils. Stores calcium ions in a relaxed muscle. Release triggers muscle contraction. Has enlarged terminal cisterns in close contact with T tubules at the junctions between A and I bands.

Transverse Tubules

  • Extensive tubular network that opens to the extracellular space.
  • Carry the depolarization (action potential) from the sarcolemma to the cell interior.

Sarcomere

  • Functional unit of skeletal muscle.
  • Constructed from thick and thin filaments.
  • Thick filaments (myosin) and thin filaments (actin, tropomyosin, troponin).

Muscle Proteins

  • Contractile proteins: Myosin and actin. Generate force during contraction.
  • Regulatory proteins: Troponin and tropomyosin. Help switch the contraction process on and off. Regulate interactions between myosin and actin.
  • Structural proteins: Titin, myomesin, nebulin, dystrophin. Keep thick and thin filaments in proper alignment. Give myofibrils elasticity and extensibility. Link myofibrils to the sarcolemma and extracellular matrix.

Muscle Hypertrophy

  • Muscle growth from heavy training.
  • Increases diameter of muscle fibers.
  • Increases number of myofibrils.
  • Increases mitochondria and glycogen reserves.

Muscle Atrophy

  • Lack of muscle activity.
  • Reduces muscle size, tone, and power.

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