Muscle Anatomy and Physiology Quiz

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 muscle?

  • To allow for body movement by contracting (correct)
  • To transport blood throughout the body
  • To store nutrients and energy
  • To connect bones to other bones

What role do tendons play in the musculoskeletal system?

  • Cushioning joints during movement
  • Attaching muscle to bone (correct)
  • Binding bone to bone
  • Connecting muscles to other muscles

How does the structure of a muscle fiber contribute to its function?

  • Fibers contain myofibrils which enable contraction (correct)
  • Fibers are filled with fat for energy storage
  • Muscle fibers are composed only of tendons
  • Fibers are tightly bound by ligaments for support

What distinguishes isometric contraction from isotonic contraction?

<p>Isometric produces no change in muscle length, while isotonic changes length (A)</p> Signup and view all the answers

Which type of muscle is responsible for involuntary movements in organs?

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

What is a characteristic feature of striated muscle?

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

Which type of muscle is related to smooth muscle but is primarily found in the heart?

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

What is the purpose of the epimysium in muscle anatomy?

<p>To bind fascicles together and protect the muscle (C)</p> Signup and view all the answers

Which statement correctly describes antagonistic muscle pairs?

<p>One muscle contracts while the other relaxes (A)</p> Signup and view all the answers

What is the primary role of intercalated discs in cardiac muscle?

<p>Provide gap junctions for communication (C)</p> Signup and view all the answers

What is true about smooth muscle?

<p>It is not under direct nervous control (A)</p> Signup and view all the answers

What component of muscle fibers is essential for the contractile process?

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

What constitutes a motor unit?

<p>One motor neuron and the associated muscle fibers (C)</p> Signup and view all the answers

How does the number of muscle fibers per motor unit affect muscle control?

<p>Fewer fibers allow for increased dexterity (A)</p> Signup and view all the answers

Which type of muscle has no striations and a high endurance capacity?

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

What is the primary function of the pace-maker in cardiac muscle?

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

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

<p>150 fibers/MU (A)</p> Signup and view all the answers

What characterizes an isometric contraction?

<p>Tension increases without a change in muscle length. (D)</p> Signup and view all the answers

In concentric isotonic contractions, what occurs?

<p>Muscle shortens and force generated is greater than the load. (C)</p> Signup and view all the answers

What happens at the neuromuscular junction (NMJ)?

<p>Nerve and muscle membranes come into close contact. (A)</p> Signup and view all the answers

What is a key feature of eccentric isotonic contractions?

<p>They can lead to damage when muscles are overloaded. (C)</p> Signup and view all the answers

How does asynchronous firing of motor units contribute to muscle contraction?

<p>It creates a smooth and graded response. (C)</p> Signup and view all the answers

Which muscle type has the fewest fibers per motor unit?

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

What is the 'all-or-nothing' response in muscle fibers?

<p>A fiber either fully contracts or does not contract at all. (B)</p> Signup and view all the answers

What is the correct duration of the twitch response in a frog after stimulation?

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

Which phase follows the latent period in muscle contraction?

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

What occurs during the refractory period of muscle contraction?

<p>Muscle is unable to respond to further stimulation (A)</p> Signup and view all the answers

What is the duration of the contraction period in a muscle twitch?

<p>0.04 sec (A)</p> Signup and view all the answers

What triggers summation in muscle contraction?

<p>Stimulation while the muscle is still contracting (D)</p> Signup and view all the answers

What indicates a state of maximal contraction in muscle physiology?

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

Which mechanism involves increasing the number of motor units to enhance contraction?

<p>Multiple motor unit summation (C)</p> Signup and view all the answers

As the impulse frequency increases beyond a certain point, what happens to the twitches?

<p>They become superimposed and fuse (A)</p> Signup and view all the answers

What is the primary distinction between the origin and insertion of a muscle?

<p>Insertion is drawn towards the origin. (A)</p> Signup and view all the answers

Which of the following best describes the function of skeletal muscles?

<p>They work in pairs to facilitate movement. (B)</p> Signup and view all the answers

Which component of a muscle fiber contains the contractile apparatus?

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

What action occurs during flexion as opposed to extension?

<p>Flexion closes a joint. (D)</p> Signup and view all the answers

How do skeletal muscles primarily work in the body?

<p>They engage in antagonistic pairs to facilitate movement. (A)</p> Signup and view all the answers

What percentage of the body's total weight is comprised of skeletal muscle?

<p>40% (D)</p> Signup and view all the answers

Which muscle type is specifically associated with the walls of the heart?

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

What primarily distinguishes isotonic contractions from isometric contractions?

<p>Isometric contractions generate tension without movement. (C)</p> Signup and view all the answers

Which characteristic is unique to smooth muscle compared to striated muscle?

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

What is the duration of the latent period in muscle contraction?

<p>0.005 seconds (A)</p> Signup and view all the answers

Which muscle type has centrally placed nuclei?

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

Which phase of muscle contraction involves the muscle shortening?

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

What distinguishes skeletal muscle from other muscle types?

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

What can occur if a second stimulation is applied during muscle contraction?

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

Which term describes the state of maximal contraction when stimuli are applied at high frequency?

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

How does the motor unit structure contribute to muscular control?

<p>Fewer muscle fibers per motor unit enhance precision (A)</p> Signup and view all the answers

Which phenomenon describes increasing the number of motor units involved in muscle contraction?

<p>Multiple motor unit summation (C)</p> Signup and view all the answers

Which of the following is true about cardiac muscle?

<p>It exhibits high endurance (C)</p> Signup and view all the answers

What time period defines the relaxation phase of muscle contraction in a frog?

<p>0.05 seconds (C)</p> Signup and view all the answers

What is the functional significance of the motor unit?

<p>It consists of a single motor neuron and its associated muscle fibers (B)</p> Signup and view all the answers

How long does the contraction period last in human muscle physiology?

<p>0.04 seconds (C)</p> Signup and view all the answers

What is a common feature of both cardiac and striated muscles?

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

During which phase does the muscle not respond to further stimulus following initial stimulation?

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

What type of contraction occurs when a muscle lengthens while tension remains constant?

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

What is the primary function of asynchronous firing of motor units during muscle contraction?

<p>To produce a graded response (D)</p> Signup and view all the answers

Which of the following statements is true regarding isometric muscle contractions?

<p>Tension in the muscle increases while length remains unchanged (A)</p> Signup and view all the answers

What describes the connection at the neuromuscular junction (NMJ)?

<p>It consists of membranes of nerve and muscle cells coming into close contact (D)</p> Signup and view all the answers

Which statement best describes concentric isotonic contractions?

<p>The muscle shortens and generates more force than the load (D)</p> Signup and view all the answers

How does the force generated during eccentric isotonic contractions compare to concentric contractions?

<p>Eccentric contractions produce more force (D)</p> Signup and view all the answers

Which muscle type has the fewest fibers per motor unit, allowing for fine motor control?

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

Flashcards

Skeletal muscle

Muscle tissue attached to bones, making up approximately 40% of the human body.

Cardiac muscle

Muscle tissue found in the heart.

Smooth muscle

Muscle tissue found in internal organs.

Tendon

Connects muscles to bones.

Signup and view all the flashcards

Ligament

Connects bone to bone.

Signup and view all the flashcards

Muscle fiber

A single muscle cell.

Signup and view all the flashcards

Origin

Fixed attachment point of a muscle.

Signup and view all the flashcards

Isometric contraction

Muscle contraction without a change in length.

Signup and view all the flashcards

Striated Muscle

A type of muscle tissue known for its striped appearance under a microscope, responsible for voluntary movements.

Signup and view all the flashcards

Muscle Biopsy

A procedure where a small sample of muscle tissue is removed using a needle, for examination under a microscope.

Signup and view all the flashcards

Hexagonal Striated Muscle

Striated muscle fibers are arranged in a hexagonal pattern with nuclei located on the outside of the fibers.

Signup and view all the flashcards

Intercalated Discs

Specialized junctions found in cardiac muscle that allow synchronized contractions, ensuring the heart beats as one unit.

Signup and view all the flashcards

Motor Unit

The functional unit of skeletal muscle, composed of a single motor neuron and the group of muscle fibers it controls.

Signup and view all the flashcards

Motor Unit and Dexterity

The number of muscle fibers per motor unit determines the precision of movement. Fewer fibers means finer control.

Signup and view all the flashcards

Twitch

A quick contraction of a muscle fiber caused by a single electrical stimulus.

Signup and view all the flashcards

Latent period

The short delay between a stimulus and the visible contraction of a muscle fiber.

Signup and view all the flashcards

Contraction period

The time during which a muscle fiber actually shortens.

Signup and view all the flashcards

Relaxation period

The time it takes for a muscle fiber to return to its resting length after contraction.

Signup and view all the flashcards

Refractory period

A brief period after stimulation when a muscle fiber is unresponsive to any further stimulus.

Signup and view all the flashcards

Summation

The increased force of muscle contraction when multiple stimuli are delivered in rapid succession.

Signup and view all the flashcards

Multiple motor unit summation

Increased force of contraction by recruiting more motor units.

Signup and view all the flashcards

Wave summation

Increased force of contraction by increasing the frequency of signals to individual motor units.

Signup and view all the flashcards

Neuromuscular junction (NMJ)

The specialized synapse between a motor neuron and a muscle fiber where nerve impulses are transmitted to the muscle.

Signup and view all the flashcards

All-or-nothing response

When a muscle fiber is stimulated at the NMJ, it will either contract completely or not at all, there's no partial contraction.

Signup and view all the flashcards

Muscle contraction: Graded response

The strength of muscle contraction is determined by the number of motor units activated.

Signup and view all the flashcards

Isotonic contraction

Muscle contraction where the tension remains constant, but muscle length changes.

Signup and view all the flashcards

Concentric contraction

Muscle shortens as it contracts, moving a load.

Signup and view all the flashcards

Eccentric contraction

Muscle lengthens while contracting, controlling the movement of a load.

Signup and view all the flashcards

What are the main muscle types?

The three main muscle types are skeletal, cardiac, and smooth. Skeletal muscle is attached to bones, cardiac muscle is found in the heart, and smooth muscle is found in internal organs.

Signup and view all the flashcards

What is a motor unit?

A motor unit is a single motor neuron and all the muscle fibers it innervates. It's the functional unit of skeletal muscle.

Signup and view all the flashcards

What is muscle twitch?

A muscle twitch is a single, quick contraction of a muscle fiber caused by a single electrical stimulus.

Signup and view all the flashcards

What is summation?

Summation is when multiple stimuli are delivered in rapid succession, causing increased force of muscle contraction.

Signup and view all the flashcards

What is isometric contraction?

Isometric contraction is when muscle tension increases but the muscle length remains the same, causing muscle stiffness. The force generated is not enough to move an object.

Signup and view all the flashcards

What is isotonic contraction?

Isotonic contraction is when the muscle tension remains constant but the muscle length changes. The muscle is strong enough to overcome the resistance.

Signup and view all the flashcards

What is concentric contraction?

Concentric contraction is when the muscle shortens as it contracts, moving a load.

Signup and view all the flashcards

What is eccentric contraction?

Eccentric contraction is when the muscle lengthens while contracting, controlling the movement of a load.

Signup and view all the flashcards

How does a muscle contract?

When a muscle fiber is stimulated at the NMJ, it contracts in an 'all-or-nothing' response.

Signup and view all the flashcards

Muscle Damage

Muscles undergoing heavy eccentric loading (like lowering a weight) suffer greater damage leading to muscle necrosis.

Signup and view all the flashcards

Fine Control

Skeletal muscles with fewer muscle fibers per motor unit allow for finer, more precise movements.

Signup and view all the flashcards

Muscle Twitch

A single, rapid contraction of a muscle fiber in response to a single electrical stimulus.

Signup and view all the flashcards

Tetanus

A state of sustained maximal contraction, resulting from high frequency stimulation where individual twitches fuse together.

Signup and view all the flashcards

Study Notes

Musculoskeletal System, Nervous System & Bioelectricity, MNB.5 Muscle Anatomy and Physiology

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

Muscle

  • Composition: About 40% of the body is skeletal muscle. There are approximately 650 skeletal muscles and over 150 surface (anatomical) muscles in the human body.

Muscle Tissue

  • Definition: Muscle is a tissue with the capability to contract.

  • Tendon: A band of fibrous connective tissue connecting muscle to bone.

  • Ligament: Connects bone to bone.

Muscle Attachment and Action

  • Origin and Insertion: Muscles are usually attached to two different bones; one attachment is fixed (origin), and the other (insertion) is pulled towards the origin.

  • Action: Movement is a result of multiple muscles working together. Muscle can only contract, not push, and they work in antagonistic pairs (e.g., flexor and extensor). A flexor closes a joint, while an extensor opens a joint.

Muscle Types

  • Skeletal Muscle: Attached to bones; voluntary; low endurance; striped/striated appearance under direct nervous control.

  • Cardiac Muscle: Found only in the heart; involuntary; high endurance; a type of striated but related to smooth muscle.

  • Smooth Muscle: Found in the walls of digestive tract, blood vessels, bronchus; involuntary; high endurance; not under direct nervous control.

Muscle Structure

  • Muscle Fibres: Composed of bundles of fascicles. Each fascicle contains many muscle fibers.

  • Myofibrils: Each fiber is composed of smaller fibers, called myofibrils. Myofibrils contain the contractile apparatus (the sarcomere).

  • Epimysium: Loose connective tissue sheath that surrounds the entire muscle.

Motor Unit (MU)

  • Definition: The functional unit of skeletal muscle.

  • Composition: A single motor neuron and the group of muscle fibers innervated by that neuron.

  • Number of fibers: The number of muscle fibers within a motor unit varies with the required control of the muscle; finer control means fewer fibers per unit. 

  • Neuromuscular Junction (NMJ): Also called the motor endplate; connection between the muscle fiber and the motor neuron; the membranes of the nerve and muscle cells come into close contact; one NMJ per muscle fiber.

  • Muscle Contraction: When a muscle fiber is stimulated at the NMJ, it contracts. The degree of contraction in a whole muscle is a function of the number of motor units stimulated. Maximum contraction is achieved when all motor units fire together. Asynchronous firing of motor units allows for graded response.

  • Muscle Twitch and Summation: The single response of a muscle to a single stimulus. The degree of contraction in a whole muscle varies based on the number of motor units firing together at any given time. Summation is when a rapid second stimulation causes a greater shortening of the muscular response. Frequency of stimulation directly impacts summation and degree of contraction (single twitch, multiple twitch, tetanus).

Types of Muscle Contractions

  • Isometric Contraction: Muscle contracts but does not shorten; tension on muscle increases and muscle length stays the same.

  • Isotonic Contraction: Muscle length changes while the tension remains constant.

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

Muscle Physiology (Further Details)

  • Whole Muscle Function: Studied via laboratory preparations such as frog's gastrocnemius muscle by stimulating the muscle and measuring its contractions and relaxation.

  • Phases of Contraction: Muscle contraction has three phases: latent period, contraction period, and relaxation period.

  • Refractory period: After initial stimulation there is a short period when muscle will not respond to further stimulus. 

Studying That Suits You

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

Quiz Team

Related Documents

MNB.05 Muscle Anatomy and Physiology PDF

More Like This

External Oblique Muscle Anatomy
10 questions

External Oblique Muscle Anatomy

StellarBrazilNutTree avatar
StellarBrazilNutTree
Muscle Anatomy Quiz
10 questions

Muscle Anatomy Quiz

FreshApostrophe avatar
FreshApostrophe
Muscle Anatomy and Physiology
19 questions

Muscle Anatomy and Physiology

FineLookingPeach996 avatar
FineLookingPeach996
Muscle Anatomy and Physiology Quiz
33 questions

Muscle Anatomy and Physiology Quiz

ReliableQuasimodo887 avatar
ReliableQuasimodo887
Use Quizgecko on...
Browser
Open
Browser
Browser