Introduction to the Nervous System 2.1A
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Introduction to the Nervous System 2.1A

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Questions and Answers

What is the primary role of the autonomic nervous system (ANS)?

  • Coordination of reflexes
  • Processing sensory information
  • Control of voluntary muscle movements
  • Regulation of involuntary body functions (correct)

    • From which areas do parasympathetic signals originate?

  • Cranial nerves and sacral spinal levels (correct)
  • Lumbar and cervical spinal levels
  • Spinal cord segments T1-L2
  • Cranial nerves and thoracic spinal levels

    • Which statement describes the sympathetic nervous system (SNS)?

  • It promotes energy conservation and relaxation.
  • It is responsible for the 'fight or flight' response. (correct)
  • It connects only to cranial nerves.
  • It regulates digestion and nutrient absorption.

    • The sympathetic signals originate from which spinal segments?

    <p>T1-L2</p> Signup and view all the answers

    What is one of the primary functions of the parasympathetic nervous system (PSNS)?

    <p>Promotes rest and digestion</p> Signup and view all the answers

    What initiates the opening of sodium channels on the postsynaptic neuron?

    <p>Release of neurotransmitter</p> Signup and view all the answers

    Which structure is primarily responsible for releasing neurotransmitters?

    <p>Axon terminal</p> Signup and view all the answers

    What role do calcium ions play in the nerve impulse process?

    <p>They initiate the release of neurotransmitter</p> Signup and view all the answers

    Which system is responsible for peripheral innervation to visceral organs and glands?

    <p>Autonomic nervous system</p> Signup and view all the answers

    What occurs immediately after neurotransmitter crosses the synaptic cleft?

    <p>Sodium channels open in the postsynaptic neuron</p> Signup and view all the answers

    Which part of the neuron receives the nerve impulse after neurotransmitter binding?

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

    How is the nervous system structurally organized?

    <p>Into central and peripheral nervous systems</p> Signup and view all the answers

    What initiates a new nerve impulse in the postsynaptic neuron?

    <p>Influx of sodium ions</p> Signup and view all the answers

    What is the sequence of events after a nerve impulse arrives at the axon terminal?

    <p>Calcium channels open, neurotransmitter released, sodium channels open</p> Signup and view all the answers

    Which division of the peripheral nervous system innervates muscles and skin?

    <p>Somatic nervous system</p> Signup and view all the answers

    What is the primary role of myelin sheaths in neurons?

    <p>To increase signal speed by allowing depolarization at nodes</p> Signup and view all the answers

    Which cell type is responsible for producing myelin sheaths around multiple axons in the central nervous system?

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

    What distinguishes myelinated axons from unmyelinated axons in terms of appearance?

    <p>Myelinated axons appear white</p> Signup and view all the answers

    What is the maximum signal speed in myelinated neurons?

    <p>3-120 m/s</p> Signup and view all the answers

    What occurs at the nodes of Ranvier in myelinated axons?

    <p>Depolarization of the neuron occurs</p> Signup and view all the answers

    How do unmyelinated neurons differ functionally from myelinated neurons?

    <p>They require depolarization at every point along their axon</p> Signup and view all the answers

    Why can myelinated neurons transmit signals more rapidly than unmyelinated neurons?

    <p>The signal jumps between nodes instead of traveling continuously</p> Signup and view all the answers

    In the context of the nervous system, what do white matter and gray matter primarily consist of?

    <p>Gray matter contains cell bodies and white matter consists of myelinated axons</p> Signup and view all the answers

    What analogy is used to describe gray matter and white matter in the nervous system?

    <p>Buildings and highways</p> Signup and view all the answers

    What is a characteristic of neuronal synapses?

    <p>They release neurotransmitters to send signals between neurons</p> Signup and view all the answers

    What is the primary function of the somatic nervous system?

    <p>Voluntary motor control and peripheral sensation</p> Signup and view all the answers

    How can dermatomes and myotomes be utilized in a clinical setting?

    <p>To determine the presence of central or peripheral injuries</p> Signup and view all the answers

    Which component of the peripheral nervous system is responsible for involuntary control?

    <p>Autonomic nervous system</p> Signup and view all the answers

    What type of nerves are spinal nerves categorized as?

    <p>Mixed nerves containing both motor and sensory fibers</p> Signup and view all the answers

    In the context of the somatic nervous system, what do myotomes refer to?

    <p>Muscle groups innervated by specific spinal nerves</p> Signup and view all the answers

    What role does the peripheral nervous system play in relation to the central nervous system?

    <p>It processes information from external and internal environments</p> Signup and view all the answers

    Which of the following best describes the parasympathetic nervous system's function?

    <p>Controls the body's 'feed and breed' functions</p> Signup and view all the answers

    Which type of control does the somatic nervous system primarily facilitate?

    <p>Voluntary control of skeletal muscles</p> Signup and view all the answers

    What is the main processing center of the nervous system?

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

    Which type of neuron transmits signals from the CNS to target organs?

    <p>Multipolar motor neuron</p> Signup and view all the answers

    Which component of the nervous system is responsible for supporting neurons?

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

    What distinguishes white matter from gray matter?

    <p>Presence of myelin sheaths</p> Signup and view all the answers

    Which part of the neuron is responsible for collecting information from other neurons?

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

    What is the role of the myelin sheath?

    <p>To increase the speed of signal transmission</p> Signup and view all the answers

    Which statement correctly describes motor neurons?

    <p>They transmit action potentials from the CNS to target organs.</p> Signup and view all the answers

    What occurs at the nodes of Ranvier?

    <p>Action potentials are actively regenerated</p> Signup and view all the answers

    What causes the symptoms of multiple sclerosis?

    <p>Loss of myelin in the CNS</p> Signup and view all the answers

    Which best describes the central process of a pseudounipolar sensory neuron?

    <p>Sensory input from the peripheral body</p> Signup and view all the answers

    How does the peripheral nervous system differ from the central nervous system structurally?

    <p>It consists of nerves extending into the body.</p> Signup and view all the answers

    What is a key difference between somatic and autonomic nervous systems?

    <p>Somatic controls voluntary actions; autonomic controls involuntary functions.</p> Signup and view all the answers

    Which type of glial cell is responsible for myelination in the peripheral nervous system?

    <p>Schwann cell</p> Signup and view all the answers

    Which part of the neuron is responsible for summating signals to reach the action potential threshold?

    <p>Axon hillock</p> Signup and view all the answers

    Which description best represents the primary function of the parasympathetic nervous system?

    <p>Manages the 'feed and breed' or 'rest and digest' processes</p> Signup and view all the answers

    From which regions of the body do sympathetic signals originate?

    <p>Spinal segments T1-L2</p> Signup and view all the answers

    What is commonly referred to as the 'fight or flight' system?

    <p>Sympathetic nervous system</p> Signup and view all the answers

    Which statement accurately describes the origin of parasympathetic signals?

    <p>They arise from cranial nerves and sacral spinal levels</p> Signup and view all the answers

    Which system primarily regulates involuntary control of visceral organs?

    <p>Autonomic nervous system</p> Signup and view all the answers

    What is the primary reason that myelinated neurons can transmit signals faster than unmyelinated neurons?

    <p>Myelination allows for depolarization at discrete nodes.</p> Signup and view all the answers

    Which glial cell type is responsible for forming myelin sheaths around multiple axons in the central nervous system?

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

    What appearance do myelinated axons typically exhibit?

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

    How does the speed of signal transmission in unmyelinated neurons compare to that of myelinated neurons?

    <p>Unmyelinated neurons transmit signals slower.</p> Signup and view all the answers

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

    <p>To allow saltatory conduction</p> Signup and view all the answers

    In terms of structural organization, how can gray matter be analogized?

    <p>As buildings processing information</p> Signup and view all the answers

    Which characteristic pertains to unmyelinated neurons in terms of action potential propagation?

    <p>They require depolarization along the entire length.</p> Signup and view all the answers

    What significant feature differentiates myelinated axons from unmyelinated axons?

    <p>Number of depolarization sites</p> Signup and view all the answers

    What defines the speed range for signal transmission in myelinated neurons?

    <p>3-120 m/s</p> Signup and view all the answers

    Which cellular structure forms the myelin sheath around a single section of an axon?

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

    What component of the nervous system is primarily responsible for voluntary motor control?

    <p>Somatic nervous system</p> Signup and view all the answers

    What tool can be used to determine the level of injury in relation to dermatomes and myotomes?

    <p>Pattern mapping</p> Signup and view all the answers

    Which structure is associated with voluntary control of skeletal muscle?

    <p>Somatic nervous system</p> Signup and view all the answers

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

    <p>Receiving external stimuli</p> Signup and view all the answers

    Which type of information is processed through the spinal nerves in the somatic nervous system?

    <p>Voluntary movements</p> Signup and view all the answers

    Which best describes the relationship between dermatomes and motor control?

    <p>Dermatomes correspond to specific spinal nerves facilitating motor control.</p> Signup and view all the answers

    What aspect of the somatic nervous system is involved in the sensation of touch?

    <p>Sensory components</p> Signup and view all the answers

    What is the primary outcome of mapping myotomes in a clinical setting?

    <p>Determining muscle strength and function</p> Signup and view all the answers

    What initiates the flow of sodium ions into the dendrite of the postsynaptic neuron?

    <p>Binding of neurotransmitter to receptors</p> Signup and view all the answers

    In which part of the neuron does the impulse arrive initially?

    <p>Axon terminal</p> Signup and view all the answers

    What primary role do calcium ions play in the process of synaptic transmission?

    <p>They trigger the release of neurotransmitters</p> Signup and view all the answers

    What occurs after sodium ions flow into the postsynaptic neuron?

    <p>A new nerve impulse is initiated</p> Signup and view all the answers

    Which division of the nervous system is primarily responsible for voluntary control?

    <p>Somatic nervous system</p> Signup and view all the answers

    What structural division does the spinal cord belong to?

    <p>Central nervous system</p> Signup and view all the answers

    Which of the following correctly describes the synapse?

    <p>It allows neurotransmitters to cross a gap</p> Signup and view all the answers

    What happens to the neurotransmitter after it crosses the synaptic cleft?

    <p>It is broken down by enzymes</p> Signup and view all the answers

    Which component does the autonomic nervous system primarily innervate?

    <p>Lungs and heart</p> Signup and view all the answers

    What is a critical function of the postsynaptic neuron during synaptic transmission?

    <p>To propagate the nerve impulse</p> Signup and view all the answers

    What is the main structural difference between the central nervous system (CNS) and the peripheral nervous system (PNS)?

    <p>CNS involves integration of activities; PNS extends into the periphery.</p> Signup and view all the answers

    Which type of neuron is primarily responsible for transmitting signals to target organs?

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

    What role does myelin play in the nervous system?

    <p>It insulates axons to increase the speed of nerve impulses.</p> Signup and view all the answers

    Which of the following best describes the composition of white matter in the nervous system?

    <p>Made up of myelinated axons</p> Signup and view all the answers

    What distinguishes neurolgia from neurons in the nervous system?

    <p>Neuroglia support neurons but do not transmit impulses.</p> Signup and view all the answers

    Which part of the neuron is responsible for receiving inputs from other neurons?

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

    What is a primary function of sensory neurons?

    <p>Convey information from sensory receptors to the CNS.</p> Signup and view all the answers

    What defines the role of oligodendrocytes in the central nervous system?

    <p>Provide electrical insulation by forming myelin sheaths.</p> Signup and view all the answers

    Which autoimmune disorder is characterized by the degradation of oligodendrocytes?

    <p>Multiple sclerosis</p> Signup and view all the answers

    What is the primary role of Schwann cells in the peripheral nervous system?

    <p>Support and insulate axons by forming myelin sheaths</p> Signup and view all the answers

    Where do action potentials first originate in a neuron?

    <p>Axon hillock</p> Signup and view all the answers

    What is the function of ganglia in the nervous system?

    <p>Act as relay stations for neuron cell bodies.</p> Signup and view all the answers

    What primarily characterizes unmyelinated axons?

    <p>They lack insulation, which results in slower signal transmission.</p> Signup and view all the answers

    Which cells are considered non-excitable and support neuron function?

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

    Study Notes

    Nervous System Overview

    • The nervous system is responsible for controlling and integrating bodily functions, responding to internal and external changes.
    • Divided into the central nervous system (CNS) and the peripheral nervous system (PNS).
    • The CNS includes the brain and spinal cord, while the PNS comprises all nerves extending to the body's periphery.

    Neuron Structure and Function

    • Neurons, the fundamental units of the nervous system, transmit electrical impulses to communicate information.
    • Neuroglia, non-neuronal support cells, are five times more abundant than neurons, providing structure, nourishment, insulation, and pathogen clearance.

    Neuron Types

    • Multipolar motor neurons: Transmit signals from the CNS to target organs.
    • Pseudounipolar sensory neurons: Transmit signals from the periphery to the CNS.

    Myelination

    • Myelin sheaths, formed by oligodendrocytes (CNS) or Schwann cells (PNS), insulate axons, increasing signal speed.
    • Multiple sclerosis: Degradation of oligodendrocytes in the CNS, leading to varying symptoms.
    • Guillain-Barré syndrome: Degradation of Schwann cells, resulting in weakness and paralysis.

    White Matter vs. Gray Matter

    • White matter: Composed of myelinated axons, appearing white due to the myelin.
    • Gray matter: Composed of neuronal cell bodies and unmyelinated axons, appearing gray.

    Action Potentials and Myelination

    • Unmyelinated neurons depolarize at every point along the axon, leading to slower signal speed.
    • Myelinated neurons depolarize only at the nodes of Ranvier, allowing for faster signal transmission (saltatory conduction).

    Neuronal Synapse

    • The synapse is the junction between two neurons, where communication occurs.
    • Neurotransmitter release from the presynaptic neuron triggers changes in the postsynaptic neuron, potentially initiating a new nerve impulse.

    Nervous System Divisions

    • Central nervous system (CNS): Brain and spinal cord, the processing center for the nervous system.
    • Peripheral nervous system (PNS): All nerves extending outside the CNS, connecting the CNS to the rest of the body.

    Autonomic Nervous System (ANS)

    • Part of the PNS responsible for involuntary control of visceral organs and glands.
    • Sympathetic nervous system (SNS): "Fight or flight" response, preparing the body for action.
    • Parasympathetic nervous system (PSNS): "Rest and digest" response, maintaining calm and conserving energy.

    Somatic Nervous System

    • Part of the PNS responsible for voluntary motor control and peripheral sensation (touch, temperature, pain).
    • Dermatomes: Areas of skin innervated by specific spinal nerves, used for diagnosing nerve damage.
    • Myotomes: Muscles innervated by specific spinal nerves, also used for diagnosing nerve damage.

    Nervous System Function

    • The CNS receives sensory information from the external and internal environments via the PNS.
    • It processes this information and initiates appropriate responses via the motor system, both voluntary (somatic) and involuntary (autonomic) pathways.

    Nervous System Organization

    • The central nervous system (CNS) includes the brain and spinal cord.
    • The peripheral nervous system (PNS) comprises all nerves extending from the CNS.
    • The nervous system is divided into the CNS and PNS structurally.
    • The nervous system is also divided into the autonomic and somatic nervous systems functionally.

    Neuronal Structure

    • Neurons are the basic unit of the nervous system.
    • They transmit electrical impulses to communicate information.
    • Neuroglia supports neurons and are 5x more abundant.
    • Neuroglia provides structural support, nourishment, insulation, and pathogen clearance.
    • Myelin insulates axons and increases signal speed.
    • Oligodendrocytes form myelin sheaths in the CNS.
    • Schwann cells form myelin sheaths in the PNS.

    Motor Neurons

    • Multipolar motor neurons transmit signals from the CNS to target organs.
    • They have a cell body, dendrites, an axon, and axon terminals.
    • The axon hillock is where signals summate to reach threshold and trigger an action potential.

    Sensory Neurons

    • Pseudounipolar sensory neurons transmit signals from the periphery to the CNS.
    • They have a cell body, dendrites, an axon, and axon terminals.
    • Sensory neurons collect information from other neurons and cells.

    Myelination and Action Potentials

    • Myelin sheaths increase signal speed by allowing action potentials to jump from node to node.
    • Unmyelinated neurons have a slower signal speed because they must depolarize at every point along the axon.
    • Multiple sclerosis is a degradation of oligodendrocytes in the CNS, leading to various symptoms.
    • Guillain-Barré Syndrome is a degradation of Schwann cells in the PNS, leading to weakness and paralysis.

    Grey vs White Matter

    • Grey matter contains cell bodies but no myelin, appearing grey.
    • White matter contains myelinated axons, appearing white.
    • Grey matter represents the information processing and storage centers of the CNS.
    • White matter represents the pathways and connections between the grey matter centers.

    Neuronal Synapse

    • Synapses are junctions between neurons for communication.
    • When a nerve impulse arrives at the axon terminal, calcium channels open, and neurotransmitters are released.
    • Neurotransmitters cross the synaptic cleft and initiate a new nerve impulse in the postsynaptic neuron.

    Autonomic Nervous System

    • The autonomic nervous system controls involuntary functions of organs and glands.
    • It is part of the PNS.
    • The parasympathetic nervous system (PSNS) is associated with "feed and breed" or "rest and digest" functions.
    • The sympathetic nervous system (SNS) is associated with "fight or flight" functions.

    Somatic Nervous System

    • The somatic nervous system controls voluntary movement and peripheral sensation.
    • It is part of the PNS.
    • Spinal nerves associate with specific levels, creating patterned myotomes (motor) and dermatomes (sensory).
    • Dermatomes and myotomes can be used to diagnose the location and level of injury.

    Functional Overview

    • The CNS receives sensory input from the PNS.
    • The CNS processes this information and initiates a motor response via the PNS.
    • The somatic nervous system controls skeletal muscle, while the autonomic nervous system controls organs and glands.
    • The parasympathetic system conserves energy, while the sympathetic system expends energy.

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    Test your knowledge on the nervous system, including its structure and function. This quiz covers topics such as neuron types, myelination, and the distinction between the central and peripheral nervous systems.

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