Nervous System Physiology Essentials 3
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Questions and Answers

What initiates the opening of voltage-gated Ca+2 channels in the presynaptic neuron?

  • Depolarization of the presynaptic neuron (correct)
  • Binding of Ach to receptors
  • Increased intracellular Ca+2 concentration
  • Release of neurotransmitters

    • Which neurotransmitter is released into the synaptic cleft after fusion of the vesicle?

  • GABA
  • Glutamate
  • Serotonin
  • Acetylcholine (Ach) (correct)

    • What type of receptor does Ach bind to on the postsynaptic membrane?

  • Calcium channel
  • Ligand-gated ion channel (correct)
  • Mechanically-gated ion channel
  • Voltage-gated ion channel

    • Which ions primarily flow through the nicotinic Ach receptor upon activation?

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

    The miniature motor end plate potential is characterized as what type of potential?

    <p>Graded potential</p> Signup and view all the answers

    What occurs when the membrane resting potential reaches the threshold value?

    <p>A true action potential is initiated</p> Signup and view all the answers

    What role does glutamate play in the central nervous system?

    <p>Excitatory neurotransmitter for learning and memory</p> Signup and view all the answers

    What is the primary function of GABA in the central nervous system?

    <p>Provides calming effects and inhibits overstimulation</p> Signup and view all the answers

    What is the primary mechanism of action of botulinum toxin?

    <p>Destroys SNARE proteins including SNAP-25</p> Signup and view all the answers

    Which of the following conditions is NOT treated with botulinum toxin?

    <p>Spastic paralysis</p> Signup and view all the answers

    What is a common source of botulinum toxin exposure?

    <p>Homemade canned foods</p> Signup and view all the answers

    How does tetanus toxin affect the nervous system?

    <p>It selectively destroys synaptobrevin in inhibitory interneurons.</p> Signup and view all the answers

    What is the primary cause of muscle weakness in Lambert-Eaton syndrome?

    <p>Destruction of voltage-gated calcium channels</p> Signup and view all the answers

    What effect does curare have on the muscular system?

    <p>Blocks neuromuscular transmission</p> Signup and view all the answers

    What is the role of acetylcholine in muscle contraction?

    <p>It facilitates the release of calcium ions from the sarcoplasmic reticulum.</p> Signup and view all the answers

    What is the effect of autoantibodies in myasthenia gravis?

    <p>They block the action of acetylcholine receptors.</p> Signup and view all the answers

    What is a synapse?

    <p>The connection between a presynaptic and a postsynaptic cell.</p> Signup and view all the answers

    Which type of synapse allows for a direct connection between neurons?

    <p>Electrical synapse</p> Signup and view all the answers

    What is the main function of neurotransmitters in chemical synapses?

    <p>To transmit information across the synaptic cleft.</p> Signup and view all the answers

    What distinguishes the synaptic cleft in chemical synapses?

    <p>It is a physical space rather than a gap junction.</p> Signup and view all the answers

    Which of the following statements about gap junctions is accurate?

    <p>They allow ions to flow freely between connected cells.</p> Signup and view all the answers

    What type of synapse forms between a neuron's axon and the soma of another neuron?

    <p>Axosomatic synapse</p> Signup and view all the answers

    What initiates the release of neurotransmitters during chemical synapse transmission?

    <p>The arrival of an action potential at the presynaptic terminal.</p> Signup and view all the answers

    Which type of synapses are categorized based on their effects on the postsynaptic neuron?

    <p>Excitatory and inhibitory synapses</p> Signup and view all the answers

    What is the role of acetylcholine in the body?

    <p>Initiates muscle contractions and affects learning and memory.</p> Signup and view all the answers

    Which characteristic distinguishes electrical synapses from chemical synapses?

    <p>Chemical synapses experience synaptic delay.</p> Signup and view all the answers

    What is the function of V-SNARE proteins?

    <p>To facilitate the fusion of vesicles with the target membrane.</p> Signup and view all the answers

    Which of the following conditions affects the neuromuscular junction?

    <p>Lambert-Eaton Syndrome</p> Signup and view all the answers

    What is the effect of botulinum toxin on muscle movement?

    <p>It blocks neurotransmitter release and causes paralysis.</p> Signup and view all the answers

    What role does synaptotagmin play in the SNARE complex formation?

    <p>It enhances assembly of the SNARE complex upon calcium binding.</p> Signup and view all the answers

    How does synaptic transmission differ between electrical and chemical synapses?

    <p>Electrical synapses have no delay, while chemical synapses experience a delay.</p> Signup and view all the answers

    What is the primary mediator in chemical synapses?

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

    What is the primary effect of curare at the neuromuscular junction?

    <p>It blocks nicotinic acetylcholine receptors and prevents muscle contraction.</p> Signup and view all the answers

    Which neurotransmitter is primarily responsible for producing EPSP?

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

    What is the effect of inhibitory neurotransmitters like GABA on the postsynaptic neuron?

    <p>They hyperpolarize the neuron, making it less likely to fire.</p> Signup and view all the answers

    What happens to acetylcholine (Ach) when curare is applied?

    <p>It accumulates in the synaptic cleft.</p> Signup and view all the answers

    What determines whether a postsynaptic neuron is stimulated or inhibited?

    <p>The balance between EPSP and IPSP.</p> Signup and view all the answers

    What occurs when sodium channels open in the postsynaptic neuron?

    <p>Depolarization leading to excitatory postsynaptic potential (EPSP).</p> Signup and view all the answers

    What is meant by convergence in neural signaling?

    <p>Signals from multiple presynaptic neurons converge onto a single postsynaptic neuron.</p> Signup and view all the answers

    Which of the following best describes IPSP?

    <p>A hyperpolarization caused by inhibitory signals making the neuron less likely to fire.</p> Signup and view all the answers

    Study Notes

    Nervous System Physiology Essentials 3

    • Nervous system physiology focuses on how neurons and other cells communicate.
    • Synapses are the connections between neurons, muscles, or glands.

    Synapses

    • A synapse is the connection between a neuron and another cell (neuron, muscle, or gland).
    • In the central nervous system (CNS), two neurons connect together at a synapse.
    • In the peripheral nervous system (PNS), one neuron can connect to a muscle or gland cell.
    • The area before the synapse is the presynaptic cell; the one after is the postsynaptic cell.
    • The synapse between a neuron and a muscle cell is called a neuromuscular junction.

    Synapse Types

    • Synapses are categorized by structure or function.
    • Structurally, there are axodendritic, axosomatic, and axoaxonic synapses.
    • Functionally, they are categorized as excitatory or inhibitory.

    Electrical Synapse

    • Electrical synapses connect cells directly via gap junctions.
    • Gap junctions allow ions to flow freely between cells.
    • The transmission is very fast and bidirectional.
    • This type of synapse is found in smooth muscle and the heart.
    • These synapses create a distance of 24nm between cells, which is shorter than a typical chemical synapse (6 times shorter).

    Chemical Synapse

    • Chemical synapses use neurotransmitters to transmit signals.
    • The synapse has a synaptic cleft (space between neurons) that is 20-40 nanometers wide.
    • Neurotransmitters are stored in vesicles at the presynaptic neuron’s axon terminal.
    • When an action potential arrives, calcium ions enter the presynaptic terminal, triggering the release of neurotransmitters into synaptic cleft.
    • Neurotransmitters bind to receptors on the postsynaptic neuron, creating an electrical signal.
    • This type of synapse is more common than electrical synapses.

    Neurotransmitters

    • Neurotransmitters are chemicals that transmit signals between nerve cells.
    • They are stored in vesicles. The release is triggered by an action potential.
    • Examples include glutamate (excitatory), GABA (inhibitory), and acetylcholine (involved in muscle contraction and learning).

    Conditions Affecting Neuromuscular Junction

    • Lambert-Eaton Syndrome: Muscles weaken due to calcium-dependent neurotransmitter release problems.
    • Botulism: Blocks the release of acetylcholine, causing paralysis.
    • Tetanus: Blocks release of inhibitory neurotransmitters, causing unwanted muscle spasms.
    • Myasthenia Gravis: Autoantibodies attack acetylcholine receptors, affecting muscle contraction.
    • Curare: Competes with acetylcholine and blocks receptors, causing muscle paralysis.

    Types of summation

    • Summation is the process where individual signals (EPSP or IPSP) combine to create a larger effect on the postsynaptic potential, triggering or suppressing an action potential.
    • Temporal summation: Successive signals from a single presynaptic neuron arrive rapidly.
    • Spatial summation: Simultaneous signals from several presynaptic neurons converge on the postsynaptic neuron.

    Convergence and Divergence

    • Convergence: Many presynaptic neurons connect to one post-synaptic neuron.
    • Divergence: Presynaptic neuron connects to many post-synaptic neurons.
    • Facilitation: Repeating a signal strengthens the neuron and makes it easier to trigger an action in a series of signals.

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    Description

    Explore the intricate workings of the nervous system in this quiz. Focus on the characteristics and types of synapses, the communication between neurons, and how these connections influence muscle and gland functions. Ideal for students delving into nervous system physiology.

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