Nervous System Organization Quiz
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Questions and Answers

What role does calcium play during an action potential in the axon terminal?

  • It aids in the storage of neurotransmitters.
  • It deactivates neurotransmitters enzymatically.
  • It activates receptors in the postsynaptic membrane.
  • It causes the release of neurotransmitters into the synaptic cleft. (correct)

    • Which of the following describes how neurotransmitters are deactivated?

  • They are only removed from the synaptic cleft.
  • They have no means of deactivation and remain active indefinitely.
  • They are destructively changed by the postsynaptic neuron.
  • They can be destroyed enzymatically or taken back into the nerve terminal. (correct)

    • How does the nervous system impact ecosystem health?

  • It solely regulates metabolic rates in animals.
  • It has no effect on the food chain.
  • It influences locomotion, behavior patterns, and feeding. (correct)
  • It determines the genetic makeup of species.

    • Why is understanding animal behavior significant for public health?

    <p>It is essential for timely health interventions.</p> Signup and view all the answers

    What happens to a neurotransmitter after it binds to a receptor in the postsynaptic membrane?

    <p>It is either destroyed or taken back for reuse.</p> Signup and view all the answers

    What are the three main components of the nervous system's organization?

    <p>Sensory, Integration, Response</p> Signup and view all the answers

    Which part of the nervous system is primarily responsible for interfacing with the external environment?

    <p>Peripheral Nervous System (PNS)</p> Signup and view all the answers

    Which component is NOT part of the cellular composition of the nervous system?

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

    What is the primary function of sensory fibers in the peripheral nervous system?

    <p>Carry sensory information from receptors</p> Signup and view all the answers

    What structures comprise the Central Nervous System (CNS)?

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

    Which type of motor fiber is considered part of the voluntary system?

    <p>Somatic motor fibers</p> Signup and view all the answers

    What is the role of the integration component in the nervous system?

    <p>Process and interpret sensory information</p> Signup and view all the answers

    Which is a characteristic of action potentials in nerve cells?

    <p>They are large changes in membrane potential.</p> Signup and view all the answers

    What is the role of neurotransmitters (NT) in muscle contraction?

    <p>They diffuse across the synaptic cleft and bind to post-synaptic receptors.</p> Signup and view all the answers

    What are the two primary mechanisms for the removal of neurotransmitters from the synaptic cleft?

    <p>Enzymatic breakdown and reuptake.</p> Signup and view all the answers

    Which receptor type is associated with the action of acetylcholine in the autonomic nervous system?

    <p>Muscarinic receptors.</p> Signup and view all the answers

    Which type of neurotransmitter is GLutamate classified as?

    <p>Excitatory.</p> Signup and view all the answers

    What happens to Na+ and K+ channels during the repolarization phase of an action potential?

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

    What type of receptors do catecholamines primarily act upon?

    <p>Adrenergic receptors.</p> Signup and view all the answers

    Which factor does NOT influence nerve conductance velocity?

    <p>Temperature of the surrounding environment</p> Signup and view all the answers

    What neurotransmitter is known to have an inhibitory effect within the central nervous system (CNS)?

    <p>GABA.</p> Signup and view all the answers

    Where is the synthesis of neurotransmitters primarily initiated?

    <p>In the nerve cell body.</p> Signup and view all the answers

    What is the main role of the Na+/K+ pump in nerve cells?

    <p>Maintains resting membrane potential</p> Signup and view all the answers

    At what voltage does threshold for action potential generation typically occur?

    <p>+30mV</p> Signup and view all the answers

    What is the effect of β2 adrenergic receptors when activated?

    <p>Promotes smooth muscle relaxation.</p> Signup and view all the answers

    Which event occurs immediately after the arrival of an action potential at a synapse?

    <p>Ca++ influx into the cell</p> Signup and view all the answers

    What effect does myelination have on nerve fiber conductance?

    <p>Reduces the time for action potential propagation</p> Signup and view all the answers

    What is the original transmembrane potential of a nerve cell before an action potential occurs?

    <p>-75mV</p> Signup and view all the answers

    What mechanism allows for the saltatory conduction of action potentials?

    <p>The presence of nodes of Ranvier</p> Signup and view all the answers

    What are the main types of neurons found in the peripheral nervous system (PNS)?

    <p>Sensory and motor neurons</p> Signup and view all the answers

    What role do transport proteins have in neuronal membranes?

    <p>Bind and transfer ions</p> Signup and view all the answers

    What is the normal resting membrane potential (RMP) of a nerve cell?

    <p>-75 mV</p> Signup and view all the answers

    During the generation of an action potential, what occurs at the threshold voltage?

    <p>AP is generated</p> Signup and view all the answers

    What is the primary effect of the sodium-potassium pump in nerve cells?

    <p>Moves sodium out and potassium into the cell</p> Signup and view all the answers

    Which ion is primarily responsible for the early phase of depolarization in an action potential?

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

    Which of the following describes the membrane's permeability characteristics at resting state?

    <p>Readily permeable to K+ and slightly to Na+</p> Signup and view all the answers

    What leads to the electrical potential across the neuronal membrane?

    <p>Difference in concentration of ions and charged particles</p> Signup and view all the answers

    Study Notes

    Nervous System Organization

    • The nervous system has three components: sensory, integration, and response.
    • The sensory component receives information from sensory organs and transmits it through sensory neurons.
    • The integration component processes information in the spinal cord and brain.
    • The response component transmits signals from the CNS via motor neurons to effector organs like muscles and glands.

    Peripheral Nervous System

    • The peripheral nervous system (PNS) is the interface between the central nervous system (CNS) and the environment.
    • It includes sensory and motor neurons.
    • Sensory fibers carry information from receptor organs like skin, viscera, and proprioceptors to the CNS.
    • Motor fibers are further divided into somatic motor (voluntary) and autonomic nerves (sympathetic and parasympathetic).

    Central Nervous System

    • The central nervous system (CNS) comprises the brain and spinal cord.

    Neuron Structure

    • The neuron is the functional unit of the nervous system.
    • The axon is the long, slender projection that transmits signals away from the cell body.
    • The axon terminal is the endpoint of the axon responsible for releasing neurotransmitters.
    • The cell body contains the nucleus and other organelles.
    • The dendrites are branched extensions that receive signals from other neurons.

    Neuroglia

    • Neurons coexist with neuroglia, which provide support and protection for neurons.

    Membrane Structure

    • The cell membrane is composed of a phospholipid bilayer.
    • Proteins embedded in the membrane play crucial roles:
      • Receptor proteins: bind neurotransmitters.
      • Channel proteins: form pores for ion movement.
      • Transport proteins: bind and transfer ions (K+ and Na+).

    Resting Membrane Potential

    • The resting membrane potential (RMP) is created by the uneven distribution of charged particles across the membrane.
    • The RMP is typically -75mV.
    • It is maintained by the sodium-potassium pump, which actively moves Na+ out of the cell and K+ into the cell.
    • Selective permeability: The membrane is more permeable to K+ than Na+, contributing to the RMP.

    Action Potential Generation

    • An action potential (AP) is a rapid change in membrane potential that allows for nerve impulse transmission.
    • The AP occurs in three stages:
      • Depolarization: Stimulation increases Na+ permeability, raising the membrane potential.
      • Threshold: When the membrane potential reaches a critical voltage (+30mV), voltage-sensitive Na+ and K+ channels open.
      • Repolarization: Na+ channels close, and K+ channels fully open, allowing K+ to flow out, returning the membrane potential to negative.

    Action Potential Propagation

    • The AP propagates down the axon.
    • Myelination: Insulation provided by myelin sheaths increases the speed of conduction by reducing ion leaks.
    • Nodes of Ranvier: Gaps in the myelin sheath that allow for rapid ion diffusion, enabling "saltatory conduction."
    • Diameter of fibers: Larger diameter fibers have greater surface area for ion diffusion, resulting in faster conduction velocity.

    Synapse

    • A synapse is the junction between two neurons or between a neuron and an effector organ.
    • It allows for the transmission of signals from one cell to another.
    • Pre-synaptic terminal: The axon terminal of the presynaptic neuron, releases neurotransmitters.
    • Post-synaptic terminal: The receptive area on the dendrite or cell body of the postsynaptic neuron.
    • Synaptic cleft: The narrow space between the pre- and post-synaptic terminals where neurotransmitters diffuse.

    Signal Transduction at the Synapse

    • Signal transmission at the synapse involves the following steps:
      1. Arrival of an Action Potential (AP) at the pre-synaptic terminal.
      2. Calcium influx into the pre-synaptic terminal.
      3. Fusion of synaptic vesicles with the pre-synaptic membrane.
      4. Exocytosis of neurotransmitters into the synaptic cleft.
      5. Diffusion of neurotransmitters across the synaptic cleft and binding to receptors on the post-synaptic membrane.
      6. Receptor activation triggers a response in the postsynaptic neuron.
      7. Removal of neurotransmitters by either enzymatic breakdown or reuptake into the pre-synaptic terminal for recycling.

    Neurotransmitters

    • Neurotransmitters (NTs) are chemical messengers that transmit signals across synapses.
    • They can be excitatory, inhibitory, or modulatory.
    • Key neurotransmitters:
      • Acetylcholine (Ach): Released at neuromuscular junctions and in the autonomic nervous system (ANS). Has both nicotinic and muscarinic receptors.
      • Catecholamines:
        • Norepinephrine (Noradrenaline): Acts on α1, α2, β1, and β2 adrenoceptors.
      • Glutamate: Excitatory within the brain.
      • Glycine: Inhibitory within the spinal cord.
      • Gama-aminobutyric acid (GABA): Inhibitory within the CNS.
      • Others: Serotonin, Dopamine, and neuropeptides.

    Acetylcholine Receptors

    • Nicotinic receptors: Found at the NMJ and in pre-ganglionic neurons of the ANS.
    • Muscarinic receptors: Found in post-ganglionic neurons of the parasympathetic nervous system.

    Adrenergic Receptors

    • β1 receptors: Located in the myocardium; excitatory effect.
    • β2 receptors: Located in smooth muscle; relaxation effect.
    • α1 receptors: Located in smooth muscle; contraction effect.

    Synthesis, Storage, Release, and Deactivation of Neurotransmitters

    • Neurotransmitter synthesis: Takes place in the cell body, axon, or axon terminal.
    • Neurotransmitter storage: Granules or vesicles in the axon terminal.
    • Neurotransmitter release: Calcium influx triggers exocytosis of neurotransmitters into the synaptic cleft.
    • Neurotransmitter deactivation: Enzymatic breakdown, reuptake into the pre-synaptic terminal for reuse, or degradation and removal.

    One Health Relevance

    • Animal health and welfare: The nervous system controls complex physiological and biochemical processes in animals, affecting their behavior and overall health.
    • Public health: Nervous system dysfunction can directly or indirectly impact behavior, productivity, and the Human-Animal bond.
    • Ecosystem health and sustainability: The nervous system influences animal feeding patterns, behavior, and locomotion, impacting the food chain.

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    Description

    Test your understanding of the nervous system, including its organization, components, and functions. This quiz covers the sensory, integration, and response components, alongside the roles of the peripheral and central nervous systems. Dive deep into the structure and function of neurons as well!

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