Muscle Tissue Types and Characteristics
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Questions and Answers

What does the 'staircase effect' refer to in muscle contractions?

  • Repeated contractions growing stronger with the same stimulus. (correct)
  • A complete tetanus state.
  • The relaxation phase of muscle contraction.
  • Decreasing strength of contractions over time.

    • Wave summation results in a decrease of overall contraction strength.

    False

    What is the function of somatic motor nerves in muscle contraction?

    They send signals from the brain or spinal cord to trigger muscle contractions.

    During the __________ phase, the muscle relaxes and returns to its resting state.

    <p>relaxation</p> Signup and view all the answers

    Match the terms related to muscle contraction with their definitions:

    <p>Latent Phase = Delay before muscle contraction begins Treppe = Gradual increase in contraction strength with repeated use Tetanus = Maximum, continuous contraction Fatigue = Muscle weakness due to energy depletion</p> Signup and view all the answers

    What is the primary characteristic of skeletal muscle?

    <p>Striated and multinucleic</p> Signup and view all the answers

    Smooth muscle is not found in the walls of hollow organs.

    <p>False</p> Signup and view all the answers

    What structure surrounds each muscle fiber?

    <p>endomysium</p> Signup and view all the answers

    Each bundle of muscle fibers wrapped in the perimysium is called a __________.

    <p>fascicle</p> Signup and view all the answers

    Which muscle type constitutes the heart muscle?

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

    Match the following terms with their descriptions:

    <p>Skeletal muscle = Controlled voluntarily and striated Smooth muscle = Involuntary and found in hollow organs Cardiac muscle = Striated and forms the heart Endomysium = Protective sheath around muscle fibers</p> Signup and view all the answers

    Each muscle cell is known as a muscle fiber.

    <p>True</p> Signup and view all the answers

    What surrounds the myofibrils within muscle fibers?

    <p>sarcoplasmic reticulum</p> Signup and view all the answers

    What is the primary function of tendons?

    <p>Connect muscles to bones</p> Signup and view all the answers

    The origin of a muscle is its more movable attachment point.

    <p>False</p> Signup and view all the answers

    What are muscles that assist the prime movers in a movement called?

    <p>Synergists</p> Signup and view all the answers

    The connective tissues that surround muscle fibers are called __________.

    <p>endomysium</p> Signup and view all the answers

    Which of the following describes fixators?

    <p>Muscles that stabilize the origin of a prime mover</p> Signup and view all the answers

    As a person ages, the mass of muscle fibers generally increases.

    <p>False</p> Signup and view all the answers

    Match the roles of muscles with their descriptions:

    <p>Prime movers = Muscles responsible for producing a particular movement Antagonists = Muscles that oppose or reverse a movement Synergists = Muscles that assist another muscle in action Fixators = Muscles that stabilize the origin of prime movers</p> Signup and view all the answers

    What type of muscle connects muscles to other muscles or bones?

    <p>Tendons</p> Signup and view all the answers

    Which group of muscles mainly originates from the axial skeleton or shoulder girdle?

    <p>Trunk muscles</p> Signup and view all the answers

    Muscles that control flexion and extension of the forearm are part of the first group of muscles.

    <p>False</p> Signup and view all the answers

    What is released by motor neurons to trigger muscle contraction?

    <p>acetylcholine</p> Signup and view all the answers

    When a muscle fiber is stimulated, the sarcolemma becomes temporarily more permeable to ______.

    <p>Na+</p> Signup and view all the answers

    Match the following processes with their descriptions:

    <p>Depolarization = Wave that allows sodium ions to enter the muscle cell Calcium Release = Initiates a series of events that lead to muscle contraction All-or-None Principle = A muscle fiber either fully contracts or does not contract at all Graded Response = The whole muscle varies how strongly it contracts</p> Signup and view all the answers

    What is the main role of muscles that cross the wrist?

    <p>Control movements of the hand and fingers</p> Signup and view all the answers

    A subthreshold stimulus is strong enough to make a muscle fiber contract.

    <p>False</p> Signup and view all the answers

    The resting membrane potential is particularly important in ______ cells.

    <p>excitable</p> Signup and view all the answers

    What is maximal stimulus?

    <p>The smallest stimulus to make all muscle fibers contract</p> Signup and view all the answers

    A muscle twitch has four phases.

    <p>False</p> Signup and view all the answers

    What happens during the contraction phase of a muscle twitch?

    <p>The muscle shortens and produces force.</p> Signup and view all the answers

    Muscle fatigue occurs when a muscle runs out of ________.

    <p>energy</p> Signup and view all the answers

    What does multiple motor unit summation (recruitment) allow a muscle to do?

    <p>Increase strength by activating more motor units</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Treppe = Contraction strength increases with repeated stimuli Wave Summation = Stronger contractions due to partial relaxation Tetanus = Sustained contraction without relaxation Muscle Fatigue = Inability to contract due to energy depletion</p> Signup and view all the answers

    Wave summation occurs when stimuli are applied after the muscle has fully relaxed.

    <p>False</p> Signup and view all the answers

    During treppe, the efficiency of contractions improves due to increased ________ and calcium levels in the muscle.

    <p>heat</p> Signup and view all the answers

    Study Notes

    Muscle Tissue Types

    • Skeletal muscle is the most prevalent muscle type in the body.
    • Smooth muscle forms the walls of internal organs and regulates lumen size.
    • Cardiac muscle makes up the heart walls.

    Skeletal Muscle Characteristics

    • Skeletal muscles are voluntary, striated, multinucleated, and cylindrical.
    • Skeletal muscle fibers (cells) range from 10 to 100 μm in length.
    • Hundreds of embryonic cells fuse to form one muscle cell.
    • Muscle cells are also called muscle fibers.

    Myofilaments & Sarcomeres

    • Myofilaments are made of actin and myosin proteins.
    • Sarcomeres are the functional contractile units of a muscle cell.
    • Each thin filament is surrounded by three thick filaments.
    • Each thick filament is surrounded by six thin filaments.

    Connective Tissue Components

    • Endomysium: A layer of connective tissue that surrounds each muscle fiber.
    • Perimysium: Another layer that bundles multiple fibers into fascicles.
    • Epimysium: A thicker layer that encloses the entire muscle.
    • Tendons and aponeuroses are formed by the convergence of these connective tissue layers, attaching muscles to bones.

    Neuromuscular Junction

    • The neuromuscular junction is where a motor neuron connects to a muscle fiber.
    • Axon terminals release acetylcholine (ACh) into the synaptic cleft, initiating muscle contraction.
    • Calcium ions (Ca2+) play a crucial role in releasing ACh.

    Muscle Contraction Steps

    • Electrical excitation of the muscle fiber.
    • Excitation-contraction coupling.
    • Shortening of the muscle fiber.

    Muscle Fatigue

    • Muscle fatigue occurs when the muscle can't contract due to factors like oxygen debt, lactic acid buildup, or depletion of ATP.

    Muscle Activity Types

    • Isometric contraction: Muscle contracts without changing length; maintaining tension, e.g., holding a weight.
    • Isotonic contraction: Muscle changes length while maintaining force; e.g., walking or lifting.

    Muscle Stimulation and Response

    • Multiple motor unit summation: Increasing force of contraction by recruiting more motor units.
    • Wave summation: Stronger contraction with repeated stimuli.
    • Tetanus (complete): Sustained/strong contraction without relaxation.

    Muscle Fiber Types

    • A muscle twitch is a single contraction and relaxation cycle. It has three phases: latent, contraction, and relaxation.
    • Treppe (staircase effect): Increased strength of contraction with repeated stimuli.
    • As you use muscles more, heat and calcium will increase the efficiency of the muscle.

    Primary Function of Muscles

    • Muscles convert chemical energy to mechanical energy for movement.
    • Somatic motor neurons signal muscle contractions.

    How Skeletal Muscle Contraction is Controlled

    • The brain recruits particular motor units based on strength demands.
    • Impulse frequency is controlled by the brain to ensure desired levels of strength and sustained contractions
    • The body can adjust the strength of muscle contraction by adjusting the number of recruited motor units or the rate at which they are stimulated.

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    Description

    Explore the different types of muscle tissue, including skeletal, smooth, and cardiac muscle. This quiz covers key characteristics of skeletal muscles, the structure of myofilaments and sarcomeres, as well as connective tissue components such as endomysium, perimysium, and epimysium. Test your knowledge and understanding of muscle tissue anatomy and function.

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