Synaptic Transmission Quiz
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Questions and Answers

What primarily determines whether a postsynaptic neuron is excited or inhibited?

  • The type of neurotransmitter and receptor (correct)
  • The size of the neuron
  • The distance between neurons
  • The amount of neurotransmitter released

    • Electrical synapses allow neurotransmitters to be released into the synaptic cleft.

    False

    What is the role of mitochondria in the presynaptic terminal?

    They provide energy for neurotransmitter release.

    In a conjoint synapse, the transmission of impulses occurs via both __________ and __________ processes.

    <p>chemical, electrical</p> Signup and view all the answers

    Match the neurotransmitters to their known functions:

    <p>Acetylcholine = Muscle control Serotonin = Mood regulation GABA = Inhibitory action Glutamate = Primary excitatory neurotransmitter</p> Signup and view all the answers

    What occurs as the number of synapses increases?

    <p>Total reaction time is prolonged</p> Signup and view all the answers

    Synaptic fatigue can increase synaptic transmission.

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

    What is the role of synaptic fatigue in the CNS?

    <p>It protects neurons from overexcitation and can stop epileptic fits.</p> Signup and view all the answers

    The __________ reflex arc is characterized by simple transmission across one synapse.

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

    Which of the following neurotransmitters causes excitatory postsynaptic potential (EPSP)?

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

    Polysynaptic reflex arcs include only one synapse.

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

    Increased __________ ion concentration in blood decreases synaptic transmission.

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

    Match the following drugs with their effect on synaptic transmission:

    <p>Anesthetic drugs = Decrease synaptic transmission Theophylline = Increase synaptic transmission Diazepam = Decrease synaptic transmission Caffeine = Increase synaptic transmission</p> Signup and view all the answers

    Which characteristic is unique to chemical synapses?

    <p>Modulation capability</p> Signup and view all the answers

    Electrical synapses require neurotransmitters to function.

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

    What is the term for the connection between a neuron and a muscle?

    <p>neuromuscular junction</p> Signup and view all the answers

    Chemical synapses are typically __________, whereas electrical synapses are __________.

    <p>unidirectional, bidirectional</p> Signup and view all the answers

    Match the synaptic characteristics with their respective types:

    <p>Chemical synapse = Sensitive to drugs Electrical synapse = Rapid transmission</p> Signup and view all the answers

    What causes the release of neurotransmitters in chemical synapses?

    <p>Voltage-gated calcium channels opening</p> Signup and view all the answers

    Postsynaptic potentials (PSP) can only be excitatory at chemical synapses.

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

    Name the process by which neurotransmitters are released into the synaptic cleft.

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

    What defines a synapse?

    <p>The junction point from one neuron to another</p> Signup and view all the answers

    Chemical synapses allow for protoplasmic continuity between presynaptic and postsynaptic neurons.

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

    What are the two main types of synapses?

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

    In divergence, a single presynaptic neuron terminates on many ______ neurons.

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

    Match the following types of synaptic connections with their characteristics:

    <p>Axo-axonic = Most excitable due to high number of Na+ channels Axo-dendritic = Least excitable Axo-somatic = Directly connected to the soma Terminal boutons = Enlarged ends of presynaptic fibers</p> Signup and view all the answers

    What is the synaptic cleft?

    <p>The space filled with neurotransmitters between neurons</p> Signup and view all the answers

    What is synaptic fatigue?

    <p>A decline in synaptic transmission after repeated stimulation.</p> Signup and view all the answers

    In convergence, multiple presynaptic neurons transmit signals to a single postsynaptic neuron.

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

    What is the average number of synaptic knobs a neuron can divide to form?

    <p>Over 2000</p> Signup and view all the answers

    Tetanus toxin causes flaccid paralysis.

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

    What effect does botulinum toxin have at the neuromuscular junction?

    <p>It blocks acetylcholine release.</p> Signup and view all the answers

    Synaptic ______ is caused by delayed inactivation of the neurotransmitter.

    <p>after discharge</p> Signup and view all the answers

    Which of the following describes the mechanism of Inhibitory Postsynaptic Potential (IPSP)?

    <p>Opening of Cl- channels and K+ channels</p> Signup and view all the answers

    What protects neurons in the CNS from overexcitation?

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

    Inhibitory Postsynaptic Potential can only be produced through direct inhibition of postsynaptic neurons.

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

    What type of summation occurs when multiple presynaptic neurons stimulate a postsynaptic neuron simultaneously?

    <p>Spatial summation</p> Signup and view all the answers

    The fatality rate of botulism can be as high as 10%.

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

    Match the following terms with their descriptions:

    <p>Tetanus toxin = Causes spastic paralysis Botulinum toxin = Causes flaccid paralysis Synaptic fatigue = Decline in transmission after stimulation Synaptic after discharge = Continued action potential after presynaptic cessation</p> Signup and view all the answers

    The synaptic potential can be graded and __________.

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

    What is the purpose of the tetanus toxoid vaccine?

    <p>To prevent tetanus infection.</p> Signup and view all the answers

    What is the primary function of presynaptic inhibition?

    <p>To inhibit release of neurotransmitters</p> Signup and view all the answers

    Match the following terms with their correct definitions:

    <p>Spatial summation = Simultaneous stimulation of many presynaptic neurons Temporal summation = Repeated stimulation of a single presynaptic neuron IPSP = Transient hyperpolarizing potential Synaptic delay = Time required to transmit signal between neurons</p> Signup and view all the answers

    The synaptic delay is typically 0.5 milliseconds.

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

    What are the two types of ions that influence inhibitory postsynaptic potentials?

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

    Study Notes

    Synaptic Transmission

    • Synapses are junction points between neurons where impulses are transmitted.
    • Information travels in the central nervous system as nerve action potentials (impulses) through a series of neurons, one after another.
    • Synaptic transmission is crucial for communication between neurons.

    Intended Learning Outcomes

    • Recognize the mode of synaptic transmission.
    • Differentiate different types of postsynaptic potentials.
    • Distinguish between presynaptic and postsynaptic inhibition.
    • Describe the features of synaptic transmission.
    • Understand neurotransmitter types and their functions.

    Synapses

    • Synapses are the connection points between neurons.
    • Impulse transmission occurs from one neuron to another across a synapse.
    • The structure comprises presynaptic and postsynaptic neurons, separated by a synaptic cleft.

    Synapses Function

    • Impulses are transmitted through a succession of neurons.
    • Impulses can be blocked in the transmission, transformed into repetitive impulses, or combined into complex patterns during transmission.
    • Synapses serve as targets for many drugs' actions.

    Synapses, Types

    • Chemical synapses are the most common type in the CNS.
    • Chemical synapses involve neurotransmitter release from a presynaptic neuron across a synaptic cleft to bind to a receptor on a postsynaptic neuron.
    • Electrical synapses transmit impulses directly between cells through gap junctions.
    • Conjoint synapses combine chemical and electrical processes.

    Chemical Synapses

    • At a chemical synapse, one neuron's axon terminal connects to another neuron's dendrites, soma, or axon.
    • The axon of a presynaptic neuron ends on the dendrites, soma, or axon of a postsynaptic neuron.

    Chemical Synapses, Types

    • Axo-dendritic connections are the least excitable.
    • Axo-somatic synapses are slightly more easily stimulated.
    • Axon-axon synapses are highly excitable, have low threshold stimulation, and possess high sodium channel density.
    • There's a synaptic cleft separating the presynaptic and postsynaptic membranes, ranging from 20-40 nanometers in width.

    Chemical Synapses; Properties

    • Presynaptic terminals contain mitochondria and membrane-bound vesicles.
    • Neurotransmitters are synthesized in the cell body and transported to the presynaptic terminals.
    • Stimulation of presynaptic neurons releases neurotransmitters via exocytosis into the synaptic cleft.
    • Neurotransmitters bind to specific receptor sites on the postsynaptic neuron.

    Neurotransmitters

    • More than 50 neurotransmitters are recognized.
    • Some well-known neurotransmitters are acetylcholine, norepinephrine, epinephrine, histamine, GABA, glycine, serotonin, and glutamate.
    • Neurotransmitters' effect depends on the receptor type on the postsynaptic neuron and the enzymatic processes in the postsynaptic neuron.

    Electrical Synapses (gap junctions)

    • Electrical synapses transmit impulses directly using gap junctions that connect the cytoplasm of adjacent cells.
    • These synapses offer rapid impulse transmission.

    Conjoint Synapses

    • Conjoint synapses utilize both chemical and electrical processes to transmit impulses.
    • Conjoint synapses are rare.

    Synaptic Transmission; Properties

    • The transmission process isn't instantaneous.
    • A synaptic delay takes around 0.5 milliseconds.
    • Neurotransmission can be determined by measuring synaptic delay in polysynaptic pathways.

    Synaptic Fatigue

    • Synaptic transmission declines after repeated stimulation.
    • Causes include neurotransmitter depletion and postsynaptic receptor downregulation.

    Synaptic Transmission; Properties; Chemical Changes

    • Synaptic transmission is influenced by chemical changes such as variations in blood H+ concentration and blood O2 levels.
    • Elevated H+ (acidosis) decreases synaptic transmission, while decreased H+ (alkalosis) increases it.
    • Decreased O2 (hypoxia) reduces synaptic transmission.

    Synaptic Transmission; Properties; Drugs

    • Certain drugs affect synaptic transmission by increasing or decreasing it.
    • For example, some anesthetic and anxiolytic drugs decrease transmission by affecting GABA receptors.
    • Other drugs, like theophylline and caffeine, can increase transmission.

    Botulism and Tetanus Toxins (Clinical Note)

    • Clostridia bacteria produce potent toxins, including botulinum and tetanus toxins.
    • Tetanus toxin blocks the release of inhibitory neurotransmitters, leading to spastic paralysis.
    • Botulinum toxin blocks acetylcholine release at neuromuscular junctions leading to flaccid paralysis.

    Postsynaptic Potentials; Types

    • A postsynaptic potential (PSP) is a temporary change in the postsynaptic membrane potential.
    • Excitatory postsynaptic potentials (EPSPs) cause depolarisation, making the neuron more likely to fire an action potential.
    • Mechanism involves opening sodium channels, increasing sodium influx.
    • Inhibitory postsynaptic potentials (IPSPs) cause hyperpolarization, making the neuron less likely to fire an action potential.
    • Mechanism includes opening chloride channels, thus promoting chloride influx.

    Postsynaptic Potentials; Summation

    • Spatial summation occurs when multiple presynaptic neurons stimulate a postsynaptic neuron simultaneously.
    • Temporal summation occurs when a single presynaptic neuron stimulates a postsynaptic neuron repeatedly in rapid succession.

    Synaptic Transmission; Properties: Additional Details

    • One primary direction of transmission: from the presynaptic to postsynaptic neuron.
    • Summation processes, which have been discussed in previous sections, are also key features.
    • Synaptic delay is the duration required for transmission from a presynaptic to a postsynaptic neuron (typically around 0.5 milliseconds), including transmitter release, receptor binding, and generation of the postsynaptic potential

    Synaptic Transmission: Contral inhibition

    • Central excitation occurs when excitatory postsynaptic potentials (EPSPs) are predominant.
    • Central inhibition occurs when inhibitory postsynaptic potentials (IPSPs) are predominant.

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    Synaptic Transmission BMS131 Fall 2024 PDF

    Description

    Test your knowledge on synaptic transmission, a key process in the nervous system that enables communication between neurons. This quiz will assess your understanding of synapse structure, types of potentials, and the roles of neurotransmitters. Prepare to differentiate between presynaptic and postsynaptic mechanisms and their functions.

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