Muscle Anatomy Quiz
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Questions and Answers

What is the primary function of the T tubules in muscle cells?

  • Anchor actin filaments at the Z line
  • Provide a pathway for blood vessels in the muscle
  • Conduct charge during depolarization of the cell (correct)
  • Store calcium ions for muscle contraction

Which component of the skeletal muscle fiber is responsible for the storage of calcium ions?

  • T tubules
  • Endomysium
  • Sarcoplasm
  • Sarcoplasmic reticulum (correct)

What defines the boundaries of a sarcomere in a skeletal muscle fiber?

  • The overlapping of myosin and actin filaments
  • The distance between two Z lines (correct)
  • The length of the A band
  • The distance between two M lines

What primarily distinguishes skeletal muscles from smooth muscles?

<p>Skeletal muscles have a striped appearance. (D)</p> Signup and view all the answers

Which statement correctly describes the I band in a sarcomere?

<p>Contains only actin filaments (B)</p> Signup and view all the answers

Which layer of tissue directly surrounds individual muscle fibers in skeletal muscles?

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

What tissue surrounds muscle fibers and groups them into fascicles?

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

Which feature is NOT characteristic of skeletal muscle tissue?

<p>Presence of intercalated discs (B)</p> Signup and view all the answers

What is the primary function of the skeletal muscle fibers?

<p>To contract and enable movement of bones. (A)</p> Signup and view all the answers

Which type of muscle tissue is primarily controlled by the autonomic nervous system?

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

How does the size of skeletal muscle fibers vary?

<p>They range from less than half an inch to just over three inches in diameter. (C)</p> Signup and view all the answers

Which of the following statements about the layers of skeletal muscle is incorrect?

<p>Endomysium is the outermost layer. (A)</p> Signup and view all the answers

What identifying feature differentiates cardiac muscle tissue from skeletal muscle?

<p>Single nuclei and intercalated discs (B)</p> Signup and view all the answers

Which statement correctly describes the histological appearance of smooth muscle?

<p>It has a non-striated appearance with one central nucleus. (A)</p> Signup and view all the answers

Which type of muscle tissue is exclusively located in the heart?

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

What is the main role of ATP in muscle contraction?

<p>To provide energy for the power stroke of myosin. (C)</p> Signup and view all the answers

Which of the following changes occur during muscle contraction?

<p>Both the H zone and I band shorten while the A band remains constant. (B)</p> Signup and view all the answers

What happens during the power stroke of muscle contraction?

<p>The myosin head releases ADP and phosphate. (C)</p> Signup and view all the answers

What causes the myosin head to detach from actin in the sliding filament model?

<p>The attachment of a new ATP molecule to the myosin head. (A)</p> Signup and view all the answers

In Duchenne Muscular Dystrophy, what aspect of muscle function is primarily affected?

<p>The structural integrity of the sarcomeres. (D)</p> Signup and view all the answers

What is the primary role of troponin in muscle contraction?

<p>To bind tropomyosin to actin and regulate muscle contraction (B)</p> Signup and view all the answers

Which of the following statements accurately describes the interaction of myosin with actin during muscle contraction?

<p>Myosin heads attach to actin only after tropomyosin is displaced (C)</p> Signup and view all the answers

During the power stroke, how do the myosin heads move in relation to the actin filaments?

<p>They pivot and pull actin toward the Z line (D)</p> Signup and view all the answers

Which regulatory protein covers the myosin head binding sites on the actin filament?

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

What triggers the release of calcium ions necessary for muscle contraction?

<p>Depolarization at the neuromuscular junction (A)</p> Signup and view all the answers

Which structure primarily regulates blood flow to the muscle fiber?

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

What is the main role of lymphatic vessels within skeletal muscle?

<p>Draining lymph relying on muscle movement (B)</p> Signup and view all the answers

What is the role of the neuromuscular junction in muscle contraction?

<p>To facilitate acetylcholine release into the synaptic cleft (B)</p> Signup and view all the answers

Which protein is NOT associated with the thin filaments in muscle contraction?

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

What initiates the rapid depolarization at the motor endplate?

<p>Binding of acetylcholine to its receptors (C)</p> Signup and view all the answers

What surrounds individual muscle fibers?

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

Which of the following is NOT a component of the sarcomere?

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

What is the primary role of satellite cells in skeletal muscle?

<p>They differentiate and multiply to form new muscle fibers. (C)</p> Signup and view all the answers

The structure that aids in conducting action potentials within muscle cells is called:

<p>T-tubule system (D)</p> Signup and view all the answers

Which connective tissue sheath surrounds each individual skeletal muscle fiber?

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

What characteristic gives skeletal muscle its striated appearance?

<p>The pattern of myofilaments (C)</p> Signup and view all the answers

Which type of muscle tissue is NOT one of the main types in the human body?

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

What is the fundamental contractile unit of skeletal muscle known as?

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

How do skeletal muscles contribute to thermoregulation in the body?

<p>By generating heat during contraction (A)</p> Signup and view all the answers

Which of the following correctly describes the bundles of muscle fibers within a skeletal muscle?

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

What role do skeletal muscles play during periods of starvation?

<p>They serve as a source of amino acids for protein synthesis. (B)</p> Signup and view all the answers

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

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

What structural feature distinguishes cardiac muscle cells from skeletal muscle cells?

<p>Short and branched shape (B)</p> Signup and view all the answers

What is a primary function of skeletal muscle tissue?

<p>Generate heat and enable voluntary movement (A)</p> Signup and view all the answers

Which of the following best describes the unique feature of cardiomyocytes?

<p>They connect via intercalated discs for synchronized contractions. (A)</p> Signup and view all the answers

Which property of muscle cells makes them contractile?

<p>Their ability to respond to stimuli (A)</p> Signup and view all the answers

How does skeletal muscle contribute to thermoregulation?

<p>Through the production of heat during contraction (C)</p> Signup and view all the answers

What type of muscle tissue is characterized as being 'striated'?

<p>Both skeletal and cardiac muscles (A)</p> Signup and view all the answers

Why do skeletal muscle cells maintain a stable number throughout life?

<p>They emerge from the fusion of multiple myoblasts. (B)</p> Signup and view all the answers

Flashcards

Skeletal Muscles

Muscles that attach to bones, enabling movements.

Muscle Fiber

A single, long, cylindrical cell that makes up a skeletal muscle.

Epimysium

The outer layer of connective tissue that surrounds the entire skeletal muscle.

Perimysium

The middle layer of connective tissue surrounding bundles of muscle fibers.

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Striated Muscle

Muscles with a striped appearance, like skeletal muscles.

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Cardiac Muscle

A type of muscle tissue found only in the heart, responsible for pumping blood. Identifying features: Striations, single nucleus, intercalated discs between cells.

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Smooth Muscle

A type of muscle tissue found in the walls of internal organs and blood vessels, responsible for involuntary movement. Identifying features: Non-striated, single spindle-shaped central nucleus.

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Non-striated Muscle

Muscle tissue with a smooth appearance under a microscope, lacking the striations found in skeletal and cardiac muscle.

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Sliding Filament Model

The mechanism by which skeletal muscles contract, involving the interaction of actin and myosin filaments.

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Actin Filaments

Thin filaments in muscle fibers composed of the protein actin, associated with regulatory proteins troponin and tropomyosin.

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Myosin Filaments

Thick filaments in muscle fibers composed of the protein myosin, with multiple heads that bind to actin.

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Tropomyosin

A long protein that covers the myosin binding sites on actin filaments, preventing muscle contraction.

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Troponin

A protein that binds to both actin and tropomyosin, and can bind calcium ions.

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Sarcomere

The basic functional unit of a muscle fiber, responsible for muscle contraction. It's the space between two Z lines.

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What happens during the power stroke?

The myosin head bends, pulling the actin filament along, releasing ADP and phosphate.

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What is ATP's role in muscle contraction?

ATP binds to myosin, causing detachment from actin, and is then hydrolyzed to 'recock' the myosin head.

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Duchenne Muscular Dystrophy

A genetic disorder characterized by progressive muscle weakness and degeneration, caused by a faulty gene for the protein dystrophin.

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Sarcolemma

The cell membrane of a muscle fiber.

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T tubules

Invaginations of the sarcolemma that conduct electrical signals deep into the muscle fiber.

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Sarcoplasmic reticulum

Specialized endoplasmic reticulum in muscle cells that stores calcium ions.

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Z line

The point where actin filaments are anchored in a sarcomere.

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Muscle Tissue

Tissue responsible for movement, characterized by excitability and contractility. Muscle cells respond to stimuli and shorten to generate force.

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Myocytes

Muscle cells, particularly in skeletal muscle, responsible for contraction.

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Striations

The alternating bands of light and dark seen in skeletal and cardiac muscle under a microscope. They are caused by the arrangement of contractile proteins (actin and myosin).

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Intercalated Discs

Specialized junctions between cardiomyocytes that allow for synchronized contractions and rapid communication.

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Syncytium

A group of cells that function as a single unit, like in cardiac muscle where the interconnected cardiomyocytes work together to pump blood.

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Microvascular Unit

A network of capillaries within the endomysium of a muscle fiber that regulates blood flow.

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Lymphatic Capillaries

Tiny vessels within the endomysium that collect excess fluid and transport it away from the muscle.

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Neuromuscular Junction

The specialized site where a motor neuron communicates with a muscle fiber.

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Acetylcholine

A neurotransmitter released at the neuromuscular junction that triggers muscle contraction.

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Thick Filaments

Filaments within a sarcomere composed of myosin, responsible for pulling actin filaments during contraction.

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T-tubule System

Network of invaginations of the sarcolemma that extends into the muscle fiber, helping to spread action potentials.

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What are the three main muscle types?

The three major muscle types in the human body are skeletal, cardiac, and smooth muscles.

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What is the outermost connective tissue sheath in skeletal muscle?

Epimysium is the outermost layer of connective tissue surrounding the entire skeletal muscle.

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What is a fasciculus?

A fasciculus is a bundle of muscle fibers within a skeletal muscle, wrapped by perimysium.

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What is the function of satellite cells?

Satellite cells are stem cells that differentiate into mature muscle fibers, promoting muscle growth and repair.

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What is a sarcomere?

The sarcomere is the basic contractile unit of a skeletal muscle, composed of myofibrils arranged in a striated pattern.

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What is the function of the sliding filament model?

The sliding filament model describes how actin and myosin filaments interact to cause muscle contraction.

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What are the roles of actin and myosin?

Actin is the thin filament, while myosin is the thick filament; they interact during contraction.

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What is the importance of excitation-contraction coupling?

Excitation-contraction coupling is the process by which electrical signals trigger muscle contraction.

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Study Notes

Muscle Tissue Types

  • Muscle tissue is characterized by properties allowing movement. Muscle cells are excitable, they respond to a stimulus.
  • Muscle tissue is known as being contractible, meaning they shorten and generate a pulling force.
  • When attached between two movable objects, such as bones, contraction of the muscles causes movement.
  • Muscle tissue is classified in three types according to structure and function: skeletal, cardiac, and smooth.

Skeletal Muscle

  • Structural elements: Long, cylindrical fibers; striated; many peripherally located nuclei.
  • Function: Voluntary movement; produces heat; protects organs.
  • Location: Attached to bones; various body entry and exit sites (e.g., mouth, anus).

Cardiac Muscle

  • Structural elements: Short, branched fibers; striated; single central nucleus.
  • Function: Contracts to pump blood.
  • Location: Heart

Smooth Muscle

  • Structural elements: Short, spindle-shaped; no evident striation; single nucleus in each fiber.
  • Function: Involuntary movement; moves food, involuntary control of respiration; regulates flow of blood in arteries.
  • Location: Walls of major organs; passageways.

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Description

Test your knowledge of skeletal muscle anatomy with this quiz. It covers key concepts such as muscle fiber components, sarcomere structure, and tissue classification. Perfect for students studying human anatomy and physiology.

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