Muscle Physiology Quiz
32 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of skeletal muscles?

  • Heat production
  • Movement (correct)
  • Storage of glucose
  • Protection of nerves

Which of the following characteristics allows muscle cells to respond to stimuli?

  • Extensibility
  • Excitability (correct)
  • Contractility
  • Elasticity

What is the innermost connective tissue layer surrounding a muscle fiber called?

  • Perimysium
  • Endomysium (correct)
  • Epimysium
  • Myofilament

Which muscle type is characterized by voluntary control and striation?

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

What are the smallest contractile elements of a muscle unit?

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

Which connective tissue layer surrounds a muscle fascicle?

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

What is the functional unit of a muscle cell called?

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

Which muscle type is involuntary and has a single centrally located nucleus?

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

What initiates the power stroke during muscle contraction?

<p>The separation of phosphate from the myosin head (C)</p> Signup and view all the answers

What role does ATP play in the muscle contraction cycle?

<p>It aids in the reuptake of calcium ions after contraction (B)</p> Signup and view all the answers

Which sequence of events correctly describes the process immediately after muscle contraction?

<p>Troponin-tropomyosin returns to resting position, and calcium reuptake occurs (A)</p> Signup and view all the answers

What happens to myosin heads after the power stroke is completed?

<p>They release ADP and bind to a new ATP molecule (C)</p> Signup and view all the answers

What is the function of acetylcholinesterase (AChE) in muscle contraction?

<p>To degrade acetylcholine and stop muscle contraction (B)</p> Signup and view all the answers

When does the muscle relaxation process begin?

<p>When acetylcholine is degraded in the synaptic cleft (B)</p> Signup and view all the answers

What is the primary function of the SERCA channel during muscle relaxation?

<p>To pump calcium ions back into the sarcoplasmic reticulum (D)</p> Signup and view all the answers

What is the role of tropomyosin in muscle contraction?

<p>To block myosin head binding sites on actin at rest (D)</p> Signup and view all the answers

What is the primary role of tropomyosin in muscle contraction?

<p>To cover the active points of actin (D)</p> Signup and view all the answers

What protein connects myosin to the Z line in the muscle fiber structure?

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

Which of the following structures exclusively contains thick filaments?

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

What is the significance of the dystrophin-glycoprotein complex in muscle cells?

<p>It provides stability and integrity to muscle fibers (B)</p> Signup and view all the answers

What type of channels open in the terminal cisternae when an action potential arrives?

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

How many myosin filaments are typically present in a single myofibril?

<p>1500 (C)</p> Signup and view all the answers

Which protein is responsible for producing F-actin from G-actins?

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

What structure is formed by one T tubule and two terminal cisternae?

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

What is the initial energy source used during muscle contraction?

<p>ATP stored in muscle fibers (D)</p> Signup and view all the answers

Which process follows the use of creatine phosphate in muscle energy production?

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

What is the role of the motor neuron in muscle contraction?

<p>To innervate muscle fibers for contraction (D)</p> Signup and view all the answers

What is meant by recruitment in muscle contraction?

<p>Activation of additional motor units for stronger contraction (C)</p> Signup and view all the answers

The size of a motor unit is determined by what?

<p>The number of muscle fibers innervated (C)</p> Signup and view all the answers

What results from repeated stimulation of skeletal muscle fibers?

<p>Muscle fatigue and decreased tension (B)</p> Signup and view all the answers

Which factor is NOT a determinant of muscle contraction strength?

<p>Duration of aerobic metabolism (D)</p> Signup and view all the answers

What characteristic differentiates small motor units from large ones?

<p>Number of muscle fibers they innervate (B)</p> Signup and view all the answers

Flashcards

Muscle Excitability

The ability of muscle cells to respond to stimuli by generating action potentials.

Muscle Contractility

The ability of muscle cells to shorten and thicken, generating force.

Muscle Extensibility

The ability of muscle cells to stretch without damage.

Muscle Elasticity

The ability of muscle cells to return to their original shape after being stretched.

Signup and view all the flashcards

Myofilament

The smallest contractile unit of a muscle, consisting of actin (thin) and myosin (thick) filaments.

Signup and view all the flashcards

Myofibril

Bundles of myofilaments that form the basic structure of a muscle fiber.

Signup and view all the flashcards

Muscle Fiber

A single, elongated muscle cell, containing myofibrils, surrounded by the sarcolemma.

Signup and view all the flashcards

Endomysium

The connective tissue layer surrounding a muscle fiber, providing electrical insulation.

Signup and view all the flashcards

I band

The region of the muscle fiber where the thin (actin) filaments are located.

Signup and view all the flashcards

H zone

The region of the muscle fiber containing only thick filaments (myosin).

Signup and view all the flashcards

A band

The region of the muscle fiber encompassing both the thin and thick filaments.

Signup and view all the flashcards

M line

The central region of the H zone where non-contractile filaments connect the myosin filaments.

Signup and view all the flashcards

Z line

The region between two I bands, where the thin filaments are anchored.

Signup and view all the flashcards

TITIN

A skeletal muscle protein that connects myosin to the Z line and prevents excessive stretching of the sarcomere.

Signup and view all the flashcards

NEBULIN

A skeletal muscle protein that produces F-actin from G-actins.

Signup and view all the flashcards

α-ACTININ

A skeletal muscle protein that connects actin to the Z line.

Signup and view all the flashcards

Sliding Filament Theory

In this theory, muscle contraction is explained by the sliding of actin and myosin filaments past each other.

Signup and view all the flashcards

Tropomyosin

A protein that covers the active sites of actin in a resting muscle fiber. This prevents myosin from binding and initiating contraction.

Signup and view all the flashcards

Troponin

A protein that binds calcium ions. When calcium binds, it causes a conformational change in tropomyosin, exposing the active sites of actin.

Signup and view all the flashcards

Power Stroke

The process that results in the separation of phosphate from the myosin head. This triggers the power stroke, where the myosin head pulls the actin filament, causing the muscle to shorten.

Signup and view all the flashcards

Acetylcholinesterase (AChE)

An enzyme that breaks down acetylcholine (Ach) in the synaptic cleft. This stops the signal for muscle contraction, allowing the muscle to relax.

Signup and view all the flashcards

SERCA

A channel in the sarcoplasmic reticulum (SR) that pumps calcium ions back into the SR. This reduces calcium concentration in the cytosol, leading to muscle relaxation.

Signup and view all the flashcards

Stored ATP

The storage site for ATP in muscle cells. ATP is rapidly used during muscle contraction, so stored ATP provides a short-term energy source.

Signup and view all the flashcards

Creatine Phosphate

A high-energy phosphate compound that can quickly donate its phosphate group to ADP, regenerating ATP. This provides a temporary energy source for muscle during short bursts of intense activity.

Signup and view all the flashcards

Oxidative phosphorylation

The process where cells use oxygen to produce energy from glucose, generating ATP and water as byproducts.

Signup and view all the flashcards

Muscle endurance

The ability of a muscle to contract and relax repeatedly without fatigue.

Signup and view all the flashcards

Motor unit

A single motor neuron and all the muscle fibers it innervates.

Signup and view all the flashcards

Recruitment

The process of increasing the number of motor units activated to generate more force.

Signup and view all the flashcards

Muscle fatigue

The decrease in muscle tension during sustained contraction, caused by factors like ATP depletion and metabolic changes.

Signup and view all the flashcards

Fast-twitch muscle fibers

A type of muscle fiber that contracts fast and relies primarily on anaerobic energy production, leading to rapid fatigue.

Signup and view all the flashcards

Slow-twitch muscle fibers

A type of muscle fiber that contracts slowly and relies more on aerobic energy production, allowing for sustained activity.

Signup and view all the flashcards

Study Notes

Skeletal Muscle Contraction

  • Skeletal muscles are responsible for movement, posture maintenance, and heat production. They protect bones and internal organs.
  • Muscle cells, the fundamental units, exhibit excitability, responding to stimuli by producing action potentials.
  • Excitability allows cells to shorten and thicken, generating force.
  • Extensibility means muscles can extend without damage.
  • Elasticity allows muscles to return to their original shape.

Muscle Cell Types

  • Skeletal muscle: multinucleated, striated fibers, voluntary control; found attached to the skeleton.
  • Smooth muscle: uninucleated, spindle-shaped fibers, involuntary control; found in internal organs.
  • Cardiac muscle: uninucleated, branched fibers, involuntary control; found only in the heart.

Skeletal Muscle Structure

  • Organized into hierarchical structures: myofilaments, myofibrils, muscle fibers, fascicles, and the entire skeletal muscle itself.
  • Myofilaments are the smallest contractile elements; actin (thin) and myosin (thick) are the primary components.
  • Myofibrils are bundles of myofilaments.
  • Muscle fibers are bundles of myofibrils.
  • Fascicles are bundles of muscle fibers.
  • Skeletal muscle is the outermost layer surrounding the fascicles.
  • Endomysium, perimysium, and epimysium are the connective tissue layers surrounding muscle units in order from innermost to outermost.

Sarcomere Structure

  • Sarcomere is the functional unit of muscle.
  • I band: contains only thin filaments (actin).
  • H zone: contains only thick filaments (myosin).
  • A band: contains both thick and thin filaments.
  • M line: in the middle of the H zone, connecting thick filaments.
  • Z line: boundaries of the sarcomere.

Muscle Proteins

  • Dystrophin, titin, actinin, and desmin are important intracellular skeletal proteins for structural integrity.
  • Titin connects myosin to the Z line.
  • Nebulin produces F-actin from G-actin.
  • α-actinin connects actin to the Z line.
  • These proteins contribute stability and prevent excessive stretching of the sarcomere.

Sarcotubular System

  • Sarcolemma: surrounds muscle fiber.
  • Sarcoplasm: cytoplasm within the muscle cell.
  • Sarcoplasmic reticulum (SR): calcium storage within the muscle fiber.
  • T tubules: inward folds of sarcolemma allowing action potentials to reach the SR.
  • Triad: T tubule and 2 terminal cisternae.
  • Action potentials traveling through T tubules trigger release of Ca2+ in muscle cell.

Neuromuscular Junction

  • Neuromuscular junction is the connection between a motor neuron and muscle fiber.
  • Acetylcholine (ACh) is released from the motor neuron.
  • Ligand-gated sodium channels open causing local muscle depolarization.
  • Muscle action potential is generated causing contraction of the muscle.

Contraction Mechanism

  • ATP powers muscle contraction. Muscle contraction occurs via the sliding filament theory.
  • Calcium (Ca2+) released from SR binds to troponin and exposes myosin-binding sites on actin.
  • Myosin heads bind to actin, and ATP is hydrolyzed, causing the myosin heads to pivot and pull the actin filaments.

Muscle Fatigue

  • Skeletal muscle fatigue occurs with repeated stimulation.
  • Reduced tension and slow rate of relaxation are associated with muscle fatigue.

Muscle Fiber Types

  • Slow-twitch (Type I): endurance activities, contain substantial amount of mitochondria and capillaries.
  • Fast-twitch (Type II): strength or speed-based activities, have low amounts of mitochondria and capillaries.
  • Fast-oxidative-glycolytic (Type IIa): intermediate properties.
  • Fast-glycolytic (Type IIx): rapid strength or bursts of activity, contain almost no myoglobin.

Muscle Metabolism

  • ATP is the primary energy molecule used for muscle contraction.
  • Creatine phosphate is immediately available to regenerate ATP.
  • Aerobic respiration is used to generate ATP when adequate oxygen is present.
  • Anaerobic respiration is employed when oxygen is limited..

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Skeletal Muscle Physiology PDF 2024-2025

Description

Test your knowledge on muscle physiology with this quiz focusing on skeletal muscle functions, characteristics, and contraction mechanisms. Explore topics such as muscle types, tissue layers, and the roles of ATP and acetylcholinesterase. Perfect for students in anatomy and physiology courses.

More Like This

Chapter 9 Human and Anatomy 1
63 questions

Chapter 9 Human and Anatomy 1

PerfectStatistics2519 avatar
PerfectStatistics2519
Tema 8: Músculo esquelético y contracción muscular
20 questions

Tema 8: Músculo esquelético y contracción muscular

PhenomenalMoldavite6664 avatar
PhenomenalMoldavite6664
G book Ch. 6 Skeletal Muscle Contraction Basics
48 questions

G book Ch. 6 Skeletal Muscle Contraction Basics

VerifiablePrologue3527 avatar
VerifiablePrologue3527
İskelet Kası Fizyolojisi
41 questions

İskelet Kası Fizyolojisi

UnquestionableFresno avatar
UnquestionableFresno
Use Quizgecko on...
Browser
Open
Browser
Browser