Neuroscience Concepts Quiz
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Questions and Answers

Which of the following accurately describes the primary function of the blood-brain barrier (BBB)?

  • To actively pump waste products from the brain into the bloodstream, regardless of their toxicity.
  • To protect the brain by selectively controlling the passage of substances from the bloodstream into the brain. (correct)
  • To increase the permeability of brain capillaries to allow for enhanced immune cell infiltration during infection.
  • To facilitate the rapid diffusion of all substances into the brain tissue.

    • What is the key characteristic of the all-or-none law regarding action potentials?

  • The amplitude of the action potential is constant, regardless of the stimulus strength, as long as the threshold is reached. (correct)
  • The strength of the action potential decreases proportionally with the strength of the stimulus.
  • Action potentials have variable amplitudes depending on the type of neuron that is firing.
  • A stronger stimulus will cause a quicker action potential compared to a weaker stimulus.

    • What is the approximate value of the resting potential in a typical neuron?

  • 0 mV
  • -70 mV (correct)
  • +70 mV
  • +30 mV

    • What is the primary purpose of the refractory period in neurons?

    <p>To ensure that action potentials propagate in one direction along the axon. (D)</p> Signup and view all the answers

    What is the function of the myelin sheath?

    <p>To insulate the axon and increase the speed of action potential propagation (D)</p> Signup and view all the answers

    Which cells form the myelin sheath in the central nervous system (CNS)?

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

    During the absolute refractory period, what is the state of the neuron's ability to fire another action potential?

    <p>The neuron is completely unable to fire another action potential, regardless of stimulus strength. (A)</p> Signup and view all the answers

    What maintains the resting potential?

    <p>The sodium-potassium pump, concentration gradients of ions, and selective membrane permeability (D)</p> Signup and view all the answers

    What is the primary function of the myelin sheath?

    <p>To increase the speed of action potential conduction. (A)</p> Signup and view all the answers

    What event directly triggers the release of neurotransmitters into the synaptic cleft?

    <p>The influx of calcium ions ($Ca^{2+}$). (D)</p> Signup and view all the answers

    Which type of receptor typically leads to faster, more immediate changes in the postsynaptic membrane potential?

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

    What is the primary mechanism by which spatial summation achieves its effect on the postsynaptic neuron?

    <p>Integrating inputs from multiple presynaptic neurons simultaneously. (B)</p> Signup and view all the answers

    Which of the following is an example of an efferent neuron?

    <p>A motor neuron sending signals to a muscle to contract. (C)</p> Signup and view all the answers

    In synaptic transmission, what directly follows the binding of neurotransmitters to postsynaptic receptors?

    <p>Activation of ion channels or intracellular signaling pathways. (A)</p> Signup and view all the answers

    What is the significance of the nodes of Ranvier in myelinated axons?

    <p>They are gaps in the myelin sheath that allow for saltatory conduction. (D)</p> Signup and view all the answers

    Which of the following best describes the role of afferent neurons?

    <p>Carrying sensory information from the body to the central nervous system. (C)</p> Signup and view all the answers

    Flashcards

    Blood-Brain Barrier (BBB)

    A semi-permeable membrane separating blood and brain fluid, protecting the brain.

    Tight Junctions

    Connections between endothelial cells that form the BBB.

    All-or-None Law

    Action potential fires fully or not at all, depending on stimulus strength.

    Resting Potential

    The stable electrical charge of a neuron at rest, typically -70 mV.

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    Refractory Period

    Time after firing an action potential during which a neuron cannot fire again.

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    Absolute Refractory Period

    Phase when a neuron cannot fire any action potential, regardless of stimulus strength.

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    Relative Refractory Period

    Phase when a stronger stimulus is needed for a neuron to fire another action potential.

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    Myelin Sheath

    A fatty layer that insulates axons, speeding up signal transmission.

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    Saltatory conduction

    Action potential jumps between nodes of Ranvier on myelinated axons.

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    Afferent neurons

    Transmit sensory information to the central nervous system (CNS).

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    Efferent neurons

    Transmit motor commands from CNS to the periphery (muscles, glands).

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    Synaptic transmission steps

    Sequence involving action potential, calcium influx, neurotransmitter release, and receptor binding.

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    Ionotropic receptors

    Fast-acting receptors that open ion channels directly upon neurotransmitter binding.

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    Metabotropic receptors

    Slower receptors activating G-proteins for longer-lasting intracellular effects.

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    Spatial summation

    Cumulative effect when multiple presynaptic neurons release neurotransmitters simultaneously.

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    Study Notes

    Blood-Brain Barrier (BBB)

    • The BBB is a selective semi-permeable membrane separating brain's extracellular fluid from blood.
    • It's formed by tight junctions between endothelial cells lining brain capillaries.
    • The BBB protects the brain from toxins and pathogens in the bloodstream.
    • It regulates the passage of nutrients and waste products.

    All-or-None Law of Action Potentials

    • The amplitude of an action potential is independent of stimulus strength.
    • If a stimulus reaches the threshold, an action potential fires fully.
    • If a stimulus is below the threshold, no action potential occurs.

    Resting Potential

    • The resting potential is the electrical potential difference across a neuron's membrane when inactive.
    • It's typically around -70 mV, with the inside more negative than the outside.
    • This is maintained by ion concentration gradients and membrane permeability.

    Refractory Period

    • The refractory period is a brief time after an action potential when a neuron cannot fire another.
    • This ensures unidirectional action potential propagation along the axon.
    • Two phases:
      • Absolute refractory period: The neuron cannot fire another action potential.
      • Relative refractory period: A stronger stimulus is needed to trigger another action potential.

    Myelin Sheath

    • The myelin sheath is a fatty insulating layer surrounding some neuron axons.
    • It's created by:
      • Schwann cells (peripheral nervous system)
      • Oligodendrocytes (central nervous system)
    • Myelin increases the speed of action potential conduction (saltatory conduction).
    • Conduction jumps between gaps in the myelin sheath (nodes of Ranvier).

    Afferent and Efferent Neurons

    • Afferent neurons transmit sensory information from the periphery to the CNS (e.g., skin to spinal cord).
    • Efferent neurons transmit motor commands from the CNS to the periphery (e.g., motor neurons to muscles).

    Synaptic Transmission

    • An action potential arrives at the axon terminal.
    • Voltage-gated calcium channels open, allowing calcium influx.
    • Calcium triggers neurotransmitter release into the synaptic cleft.
    • Neurotransmitters bind to receptors on the postsynaptic membrane.
    • This leads to a postsynaptic response (excitatory or inhibitory).

    Receptor Types

    • Ionotropic receptors: Fast-acting, directly open ion channels.
    • Metabotropic receptors: Slower, involve G-proteins and intracellular signaling.

    Spatial Summation

    • Multiple presynaptic neurons releasing neurotransmitters simultaneously can lead to a cumulative effect on a postsynaptic neuron.
    • This can potentially bring the postsynaptic neuron to threshold.

    Synaptic Events

    • Release of neurotransmitters from the presynaptic neuron.
    • Neurotransmitter binding to postsynaptic receptors.
    • Ion channel activation or intracellular signaling.
    • Signal termination (reuptake or enzymatic degradation).

    Neuropeptides (Neuromodulators)

    • Larger molecules acting as neuromodulators that influence neurotransmitter effects.
    • They often regulate complex behaviors (e.g., pain, mood).

    Neurotransmitter Removal

    • Neurotransmitters are removed via:
      • Reuptake by the presynaptic neuron.
      • Enzymatic degradation in the synaptic cleft.

    Hormones vs. Neurotransmitters

    • Hormones are chemical messengers released into the bloodstream, affecting distant target organs.
    • Neurotransmitters are released at synapses, affecting nearby neurons or target cells directly.

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    Related Documents

    UNIT 1 Study Guide PDF

    Description

    Test your knowledge on key neuroscience principles including the Blood-Brain Barrier, action potentials, resting potential, and the refractory period. This quiz covers essential concepts that are fundamental to understanding neural function and communication.

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