Neuromuscular Physiology and NMJ Quiz
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Questions and Answers

Which type of muscle is responsible for voluntary actions?

  • Muscle fiber
  • Skeletal muscle (correct)
  • Cardiac muscle
  • Smooth muscle

    • What is the shape of cardiac muscle?

  • Multinucleated and tubular
  • Branched and contain intercalated discs (correct)
  • Mononucleated and tubular
  • Smooth and elongated

    • What is the functional contractile unit of a muscle?

  • Myelinated α motor neuron
  • Motor unit (correct)
  • Motor neuron
  • Muscle fiber

    • Which type of muscle fibers appear red due to high contents of myoglobin, mitochondria, and capillaries?

    <p>Slow muscle fibers</p> Signup and view all the answers

    What is the role of the Neuromuscular Junction (NMJ)?

    <p>To transmit electrical impulses from the nerve terminal to the skeletal muscle</p> Signup and view all the answers

    Which structure in the NMJ contains the enzyme responsible for hydrolysis of free acetylcholine?

    <p>Synaptic cleft</p> Signup and view all the answers

    What is the role of synaptic plasticity in neuromuscular transmission?

    <p>To respond to either use or disuse of individual synaptic junctions</p> Signup and view all the answers

    Which component is part of the Neuromuscular Junction (NMJ)?

    <p>The presynaptic nerve terminal</p> Signup and view all the answers

    What percentage of total body mass is composed of muscles?

    <p>45% to 50%</p> Signup and view all the answers

    Which type of muscle is responsible for functions related to the cardiovascular, respiratory, gastrointestinal, and genitourinary systems?

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

    What is the shape of skeletal muscle cells?

    <p>Multinucleated and tubular</p> Signup and view all the answers

    Which muscle type is involved in hypertension, atherosclerosis, asthma, and disorders of the gastrointestinal tract?

    <p>Smooth Muscle</p> Signup and view all the answers

    Where do the large myelinated α motor neurons that innervate vertebrate skeletal muscles originate from?

    <p>The spinal cord</p> Signup and view all the answers

    What is the functional contractile unit of a muscle?

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

    Which muscle type appears red due to high contents of myoglobin, mitochondria, and capillaries?

    <p>Skeletal Muscle</p> Signup and view all the answers

    What is the shape of cardiac muscle cells?

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

    Which type of muscle is responsible for voluntary actions?

    <p>Skeletal Muscle</p> Signup and view all the answers

    Which type of muscle fibers have a high resistance to fatigue?

    <p>Red slow muscle fibers</p> Signup and view all the answers

    What are the three structures that comprise the Neuromuscular Junction (NMJ)?

    <p>Motor neuron, muscle fiber, and glial cells</p> Signup and view all the answers

    What is the role of acetylcholine in neuromuscular transmission?

    <p>To transmit electrical impulses from the nerve terminal to the skeletal muscle</p> Signup and view all the answers

    Where are synaptic vesicles (SVs) synthesized in the neuronal cell?

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

    What is the function of calcium ion signaling in acetylcholine vesicles exocytosis?

    <p>To mediate the process of acetylcholine vesicles exocytosis</p> Signup and view all the answers

    What happens to the released acetylcholine during diffusion across the synaptic cleft?

    <p>Nearly 50% of it is rapidly hydrolyzed by acetylcholinesterase</p> Signup and view all the answers

    What are the products of the hydrolysis of acetylcholine by acetylcholinesterase?

    <p>Choline and acetate</p> Signup and view all the answers

    What is the role of synaptic cleft in neuromuscular transmission?

    <p>To separate nerve and muscle fiber plasma membranes</p> Signup and view all the answers

    What is the role of the postsynaptic muscle membrane in the Neuromuscular Junction (NMJ)?

    <p>To oppose the nerve terminal and contain secondary folds</p> Signup and view all the answers

    What is the role of synaptic plasticity in neuromuscular transmission?

    <p>The ability of individual synaptic junctions to respond to either use or disuse</p> Signup and view all the answers

    Which type of muscle is responsible for functions related to the cardiovascular, respiratory, gastrointestinal, and genitourinary systems?

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

    What is the role of acetylcholine in neuromuscular transmission?

    <p>To initiate muscle contraction</p> Signup and view all the answers

    What is the shape of cardiac muscle cells?

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

    What is the functional contractile unit of a muscle?

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

    What percentage of total body mass is composed of muscles?

    <p>40% to 50%</p> Signup and view all the answers

    Which structures are involved in the Neuromuscular Junction (NMJ)?

    <p>Motor neuron, muscle fiber, Schwann cells</p> Signup and view all the answers

    What is the role of acetylcholine in neuromuscular transmission?

    <p>Binding to nicotinic receptors on the muscle membrane</p> Signup and view all the answers

    What is the function of calcium ion signaling in acetylcholine vesicles exocytosis?

    <p>Mediation of vesicle exocytosis</p> Signup and view all the answers

    Where are synaptic vesicles (SVs) synthesized in the neuronal cell?

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

    What percentage of the released acetylcholine is rapidly hydrolyzed by acetylcholinesterase during diffusion across the synaptic cleft?

    <p>50%</p> Signup and view all the answers

    Which type of muscle is responsible for voluntary actions?

    <p>Skeletal Muscle</p> Signup and view all the answers

    What is the shape of cardiac muscle cells?

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

    What is the role of smooth muscle in the body?

    <p>Subserve functions related to the cardiovascular, respiratory, gastrointestinal, and genitourinary systems</p> Signup and view all the answers

    What is the functional contractile unit of a muscle?

    <p>Muscle Fiber</p> Signup and view all the answers

    Where do the large myelinated α motor neurons that innervate vertebrate skeletal muscles originate from?

    <p>Spinal Cord</p> Signup and view all the answers

    Which type of muscle fibers have a high resistance to fatigue?

    <p>Red slow muscle fibers</p> Signup and view all the answers

    What is the role of acetylcholine in neuromuscular transmission?

    <p>Transmission of electrical impulses</p> Signup and view all the answers

    What is the function of calcium ion signaling in acetylcholine vesicles exocytosis?

    <p>Triggering exocytosis of acetylcholine vesicles</p> Signup and view all the answers

    Where are synaptic vesicles (SVs) synthesized in the neuronal cell?

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

    What percentage of the released acetylcholine is rapidly hydrolyzed by acetylcholinesterase during diffusion across the synaptic cleft?

    <p>50%</p> Signup and view all the answers

    Skeletal muscles are responsible for voluntary actions.

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

    Smooth muscles are involved in hypertension, atherosclerosis, asthma, and disorders of the gastrointestinal tract.

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

    The motor unit is composed of a single myelinated α motor neuron and all muscle fibers that receive innervation from this single neuron.

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

    True or false: Small motor units innervate the 'red slow' muscle fibers.

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

    True or false: Large motor units innervate the 'white or pale fast' muscle fibers.

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

    True or false: The slow muscle fibers appear red due to high contents of myoglobin, mitochondria, and capillaries.

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

    True or false: The synaptic cleft contains the enzyme responsible for hydrolysis of free acetylcholine.

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

    Study Notes

    Neuromuscular Physiology

    • Muscles account for 45-50% of total body mass, with skeletal muscles making up approximately 40% of body mass.
    • Muscle cells are specialized for converting chemical energy into mechanical energy.

    Muscle Types

    • Muscles are classified into three main types: skeletal, smooth, and cardiac.
    • Skeletal muscles are multinucleated, tubular, and responsible for voluntary actions.
    • Cardiac muscles are branched, may be mono- or binucleated, and contain intercalated discs.
    • Cardiac muscles are involved in functions related to the cardiovascular, respiratory, gastrointestinal, and genitourinary systems.

    Motor Units

    • Vertebrate skeletal muscles are innervated by large myelinated α motor neurons originating from the brainstem or spinal cord.
    • A motor unit consists of a single α motor neuron and all muscle fibers innervated by it.
    • Large motor nerves innervate more muscle fibers than smaller motor nerves.
    • Small motor units innervate "red slow" muscle fibers, while large motor units innervate "white or pale fast" muscle fibers.

    The Neuromuscular Junction (NMJ)

    • The NMJ consists of three structures: motor neuron, muscle fiber, and glial cells (Schwann cells).
    • The NMJ is responsible for transmitting electrical impulses from the nerve terminal to the skeletal muscle via acetylcholine.
    • The synaptic cleft contains basal lamina with acetylcholinesterase enzyme, which hydrolyzes free acetylcholine.
    • The postsynaptic muscle membrane has highly infolded folds (secondary folds) with nAChRs concentrated at the crests and voltage-gated sodium channels in the troughs.

    Synaptic Plasticity

    • Synaptic plasticity is the ability of individual synaptic junctions to respond to use or disuse.
    • The plasticity of neuromuscular transmission depends on the synthesis, storage, and release of acetylcholine, binding to nicotinic receptors, and rapid hydrolysis by acetylcholinesterase.

    Presynaptic Region

    • Synaptic vesicles (SVs) are specialized secretory organelles that store acetylcholine.
    • SVs possess proteins involved in neurotransmitter uptake and membrane traffic.
    • Calcium ion signaling plays a crucial role in acetylcholine vesicles exocytosis.

    Acetylcholine (ACh)

    • ACh is an important neurotransmitter involved in brain functions (memory) and body functions (muscle contractions).
    • ACh is synthesized in the nerve terminal from acetyl coenzyme A and choline.
    • Each vesicle contains 5,000 to 10,000 molecules of acetylcholine, referred to as a "quantum" of transmitter.
    • Released acetylcholine is rapidly hydrolyzed by acetylcholinesterase during diffusion across the synaptic cleft.

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    Description

    Test your knowledge of neuromuscular physiology and the neuromuscular junction (NMJ) with this quiz. Learn about the components of the NMJ and how muscles make up a significant portion of our body mass.

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