Nervous System Overview
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Questions and Answers

What is the primary function of the nervous system?

  • To facilitate blood circulation
  • To control and communicate body functions (correct)
  • To provide structural support to the body
  • To regulate body temperature

    • Which part of the nervous system serves as the integration and command center?

  • Central Nervous System (correct)
  • Peripheral Nervous System
  • Somatic Nervous System
  • Autonomic Nervous System

    • What type of fiber transmits impulses from visceral organs to the brain?

  • Visceral afferent fibers (correct)
  • Efferent fibers
  • Sensory afferent fibers
  • Skeletal muscle fibers

    • Which division of the peripheral nervous system controls skeletal muscles consciously?

    <p>Somatic Nervous System</p> Signup and view all the answers

    What are the two principal cell types of the nervous system?

    <p>Neurons and glial cells</p> Signup and view all the answers

    What is the role of supporting cells in the nervous system?

    <p>To surround and support neurons</p> Signup and view all the answers

    Which component of the autonomic nervous system is responsible for the 'fight or flight' response?

    <p>Sympathetic division</p> Signup and view all the answers

    Which nervous system division carries messages to and from the brain and spinal cord?

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

    What primary role do astrocytes play in the nervous system?

    <p>Support and brace neurons</p> Signup and view all the answers

    Which type of glial cell is responsible for monitoring the health of neurons?

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

    What is the primary function of oligodendrocytes?

    <p>Wrap CNS nerve fibers with myelin</p> Signup and view all the answers

    What structure is primarily associated with the cell body of a neuron?

    <p>Nissl bodies</p> Signup and view all the answers

    Which glial cell type surrounds neuronal cell bodies in ganglia?

    <p>Satellite cells</p> Signup and view all the answers

    What is NOT a characteristic of neurons?

    <p>Short lifespan</p> Signup and view all the answers

    What do ependymal cells primarily do in the central nervous system?

    <p>Line the central cavities of the brain and spinal cord</p> Signup and view all the answers

    Which of the following glial cells is specific to the peripheral nervous system?

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

    What is the primary role of dendrites in motor neurons?

    <p>Act as input regions for receiving signals</p> Signup and view all the answers

    Which structure arises from the axon hillock?

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

    Which component of the nervous system forms the myelin sheath around axons?

    <p>Schwann cells in the PNS</p> Signup and view all the answers

    What is the main function of the myelin sheath?

    <p>Protect the axon and increase transmission speed</p> Signup and view all the answers

    What are Nodes of Ranvier?

    <p>Gaps in the myelin sheath between Schwann cells</p> Signup and view all the answers

    In which type of matter are dense collections of myelinated fibers found in the brain and spinal cord?

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

    Which type of cell is responsible for forming myelin sheaths in the central nervous system?

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

    How do long axons compare to typical axons?

    <p>They are referred to as nerve fibers</p> Signup and view all the answers

    What is one of the primary roles of astrocytes in the nervous system?

    <p>Supporting and bracing neurons</p> Signup and view all the answers

    Which characteristic distinguishes oligodendrocytes from Schwann cells?

    <p>Oligodendrocytes wrap multiple CNS nerve fibers.</p> Signup and view all the answers

    What is the primary function of microglia in the nervous system?

    <p>Serve as phagocytes monitoring neuron health</p> Signup and view all the answers

    Which structural component of a neuron is responsible for cell-to-cell signaling?

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

    What role do ependymal cells play in the central nervous system?

    <p>Producing cerebrospinal fluid</p> Signup and view all the answers

    How do satellite cells function in the peripheral nervous system?

    <p>Surrounding neuron cell bodies in ganglia</p> Signup and view all the answers

    What is a primary characteristic of neurons?

    <p>They are amitotic and long-lived.</p> Signup and view all the answers

    Which type of cells are primarily responsible for nutrient supply and chemical environment regulation in neural tissue?

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

    What characteristic allows oligodendrocytes to insulate multiple axons in the central nervous system?

    <p>Branching structure</p> Signup and view all the answers

    Which function best describes the role of the neuron cell body (soma)?

    <p>Synthesize proteins and maintain cell health.</p> Signup and view all the answers

    Which statement accurately reflects the structure of dendrites in motor neurons?

    <p>They are short, tapering, and diffusely branched processes.</p> Signup and view all the answers

    What is a function of the myelin sheath surrounding axons?

    <p>To protect the axon and increase the speed of impulse transmission.</p> Signup and view all the answers

    Which type of cells are responsible for forming the myelin sheath in the peripheral nervous system?

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

    What structure describes the gaps in the myelin sheath between adjacent Schwann cells?

    <p>Nodes of Ranvier</p> Signup and view all the answers

    What is true regarding the axons of the central nervous system compared to those in the peripheral nervous system?

    <p>Both myelinated and unmyelinated fibers are present in the CNS.</p> Signup and view all the answers

    What distinguishes white matter in the brain and spinal cord?

    <p>It consists of dense collections of myelinated fibers.</p> Signup and view all the answers

    What role do oligodendrocytes play in the central nervous system?

    <p>They form the myelin sheath around axons.</p> Signup and view all the answers

    What is the role of the sensory division in the peripheral nervous system?

    <p>It monitors and carries stimuli from sensory receptors to the brain.</p> Signup and view all the answers

    Which statement best describes the axon in terms of its function?

    <p>Axons secrete neurotransmitters and transmit action potentials.</p> Signup and view all the answers

    Which function is primarily associated with the integration role of the nervous system?

    <p>Interpreting sensory information.</p> Signup and view all the answers

    Which of the following statements is NOT true regarding the structure of an axon?

    <p>Axons are generally short and heavily branched.</p> Signup and view all the answers

    What is the function of the neurilemma in relation to the axon?

    <p>It protects the axon and plays a role in its regeneration.</p> Signup and view all the answers

    Which part of the autonomic nervous system is primarily responsible for regulating glandular activity?

    <p>Parasympathetic division.</p> Signup and view all the answers

    What is the primary function of neurons in the nervous system?

    <p>To transmit electrical signals.</p> Signup and view all the answers

    Which of the following best explains the term 'afferent' in the context of sensory nerves?

    <p>Nerves that carry signals toward the central nervous system.</p> Signup and view all the answers

    In what way do supporting cells contribute to the function of neurons?

    <p>They provide structural support and insulation.</p> Signup and view all the answers

    Which statement about the central nervous system (CNS) is accurate?

    <p>It consists of the brain and spinal cord.</p> Signup and view all the answers

    What is the primary action that occurs in the autonomic nervous system?

    <p>Regulation of involuntary body functions.</p> Signup and view all the answers

    Which glial cell type is primarily associated with myelination in the peripheral nervous system?

    <p>Schwann cells.</p> Signup and view all the answers

    What is the primary distinction between the sympathetic and parasympathetic divisions of the autonomic nervous system?

    <p>Sympathetic speeds up bodily functions; parasympathetic slows them down.</p> Signup and view all the answers

    What type of neurons make up the sensory division of the peripheral nervous system?

    <p>Pseudounipolar neurons</p> Signup and view all the answers

    Which part of a motor neuron is primarily responsible for stimulating muscle contraction or gland secretion?

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

    Which type of neuron is primarily responsible for processing and integrating information within the central nervous system?

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

    What connective tissue layer surrounds individual axons within a nerve?

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

    What characteristic differentiates the cell bodies of motor neurons from those of sensory neurons?

    <p>Motor neurons are multipolar while sensory neurons are pseudounipolar.</p> Signup and view all the answers

    Which statement correctly describes the longevity of neurons?

    <p>Neurons can live and function for a lifetime.</p> Signup and view all the answers

    Which characteristic is true about the ability of neurons to divide?

    <p>Most neurons are amitotic and cannot divide.</p> Signup and view all the answers

    What distinguishes the metabolic demand of neurons from other cell types?

    <p>Neurons have an exceptionally high metabolic rate requiring abundant oxygen and glucose.</p> Signup and view all the answers

    Which of the following best describes the axon structure in neurons?

    <p>Axons transmit electrical signals away from the cell body.</p> Signup and view all the answers

    What factor contributes to the inability of neurons to regenerate after damage?

    <p>Neurons do not contain required organelles for cell division.</p> Signup and view all the answers

    Which term describes the unique, non-dividing characteristic of most neurons?

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

    What is the role of neurogenesis in the nervous system?

    <p>It allows for the production of new neurons in specific parts of the brain.</p> Signup and view all the answers

    Which function is associated with the integration aspect of the nervous system?

    <p>Processing and interpreting sensory information.</p> Signup and view all the answers

    What is the major biosynthetic center of a neuron?

    <p>Nerve Cell Body (Soma)</p> Signup and view all the answers

    What structure is formed by the cone-shaped area from which axons arise?

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

    Which organelle within the nerve cell body is responsible for renewing cell membranes and proteins?

    <p>Chromatophilic (Nissl) bodies</p> Signup and view all the answers

    What role do neurofibrils play in the structure of a neuron?

    <p>Stabilizing the cell against tensile forces</p> Signup and view all the answers

    What is the significance of neurons requiring oxygen?

    <p>They cannot survive for more than a few minutes without it.</p> Signup and view all the answers

    What do chromatophilic (Nissl) bodies primarily consist of?

    <p>Rough ER and free ribosomes</p> Signup and view all the answers

    What is the primary function of the plasma membrane of a neuron?

    <p>Facilitating electrical and cell-to-cell signaling</p> Signup and view all the answers

    What type of signaling is facilitated by the plasma membrane of neurons?

    <p>Cell-to-cell signaling during development</p> Signup and view all the answers

    What effect does hypoxia have on neurons?

    <p>They begin to die within minutes.</p> Signup and view all the answers

    Which of the following best describes neurofibrils?

    <p>Intermediate filaments that provide structural support</p> Signup and view all the answers

    What is the primary role of dendrites in neurons?

    <p>Receive signals from other neurons</p> Signup and view all the answers

    Which structural feature is characteristic of axons?

    <p>They arise from the axon hillock</p> Signup and view all the answers

    What is the significance of axonal transport in neurons?

    <p>It facilitates the movement of substances to and from the soma</p> Signup and view all the answers

    How do dendrites compare structurally to axons?

    <p>Dendrites are short and tapering while axons are slender</p> Signup and view all the answers

    What happens to the proteins needed for axons since they lack organelles for protein synthesis?

    <p>They are delivered from the cell body</p> Signup and view all the answers

    What is a primary function of neurotransmitters secreted from axonal terminals?

    <p>To transmit signals to other neurons</p> Signup and view all the answers

    What feature distinguishes long axons, often referred to as nerve fibers?

    <p>They can be extremely long, reaching distances of several feet</p> Signup and view all the answers

    Which of the following accurately describes axon collaterals?

    <p>They arise at right angles from axons</p> Signup and view all the answers

    What term is used to describe the process in which cytoskeletal elements support axonal structure?

    <p>Axonal transport</p> Signup and view all the answers

    What specific cellular component is absent in the axons and axon hillock of neurons?

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

    What is one of the important functions of astrocytes in the nervous system?

    <p>Take up and release ions to control the ionic environment</p> Signup and view all the answers

    Why is myelin important for nerve impulse transmission?

    <p>It increases the speed and efficiency of impulse propagation</p> Signup and view all the answers

    Which of the following statements about microglia is accurate?

    <p>They play a role in engulfing pathogens</p> Signup and view all the answers

    What role do neuroglia serve in relation to neurons?

    <p>They provide mechanical support and nutrients</p> Signup and view all the answers

    Which of the following best describes the function of astrocytes in regulating nutrient supply?

    <p>They absorb glucose and nutrients from blood vessels and directly supply neurons</p> Signup and view all the answers

    What characteristic differentiates microglia from other neuroglial cells?

    <p>Microglia do not originate from neural tissue</p> Signup and view all the answers

    How do astrocytes contribute to synapse formation?

    <p>They produce molecules necessary for neural growth</p> Signup and view all the answers

    What is the potential consequence of a lack of oligodendrocytes in the CNS?

    <p>Slowed nerve impulse transmission</p> Signup and view all the answers

    Which of the following roles is NOT associated with astrocytes?

    <p>Engulfing pathogens and debris</p> Signup and view all the answers

    In terms of cell quantity in the CNS, how do astrocytes compare to other neuroglia?

    <p>They are the most abundant type of neuroglial cells</p> Signup and view all the answers

    Study Notes

    The Nervous System

    • The nervous system manages communication and control within the body.
    • The nervous system carries out three primary functions:
      • Sensory input: Detecting internal and external stimuli
      • Integration: Interpreting sensory information
      • Motor output: Initiating responses to stimuli, often by activating effector organs like muscles or glands

    Nervous System Organization

    • The nervous system breaks down into two main parts:
      • Central nervous system (CNS): Consists of the brain and spinal cord, serving as the integration and command center.
      • Peripheral nervous system (PNS): Comprises paired cranial and spinal nerves, transmitting messages to and from the CNS.

    Peripheral Nervous System (PNS)

    • The PNS splits into two functional divisions for communication:
      • Sensory (afferent) division: Carries signals to the CNS for processing:
        • Sensory afferent fibers: Carry information from skin, muscles, and joints.
        • Visceral afferent fibers: Transmit information from internal organs.
      • Motor (efferent) division: Transmits commands from the CNS to effector organs.

    Motor Division: Controlling Movement and Function

    • The motor division branches into two primary parts:
      • Somatic nervous system: Responsible for conscious control of skeletal muscles, allowing voluntary movement.
      • Autonomic nervous system (ANS): Regulates involuntary functions, controlling smooth muscle, cardiac muscle, and glands. The ANS is divided further into the sympathetic and parasympathetic systems.

    Nervous Tissue: Cells of the Nervous System

    • The nervous system contains two principal cell types:
      • Neurons: Specialized cells that transmit electrical signals, enabling communication within the nervous system.
      • Supporting cells (neuroglia or glial cells): Cells that provide essential support for neurons:
        • Offer physical scaffolding.
        • Segregate and insulate neurons.
        • Promote neuron health and growth.

    Astrocytes: The Most Abundant Glial Cells

    • Astrocytes, the most numerous and versatile glial cells, perform multiple critical functions:
      • Support and anchor neurons.
      • Connect neurons to their nutrient supplies.
      • Guide the migration of developing neurons.
      • Regulate the chemical environment around neurons.

    Other Glial Cell Types

    • Microglia: Small, phagocytic glial cells that monitor the health of neurons, removing cellular debris and pathogens.
    • Ependymal cells: Line the central cavities of the brain and spinal cord, contributing to the production and circulation of cerebrospinal fluid.

    Oligodendrocytes, Schwann Cells, and Satellite Cells

    • Oligodendrocytes: These cells create the myelin sheath around axons in the CNS, enhancing signal transmission.
    • Schwann cells: Responsible for myelin sheath formation around axons in the PNS, increasing signal speed and providing insulation.
    • Satellite cells: Surround neuron cell bodies in ganglia (collections of neuron cell bodies in the PNS), offering supportive functions.

    Neurons: Structural and Functional Units of the Nervous System

    • Neurons, the fundamental units of the nervous system, share a common structure:
      • Cell body (soma): Contains the nucleus and is the site of protein synthesis.
      • Axon: A long, slender process that transmits electrical signals (action potentials) away from the cell body.
      • Dendrites: Short, branching processes that receive incoming signals from other neurons.

    Nerve Cell Body (Soma or Perikaryon)

    • The cell body is crucial for neuron function due to:
      • Nucleus: Contains the genetic material for neuronal function.
      • Nissl bodies: (rough ER) Responsible for protein synthesis, essential for neuron growth and repair.
      • Axon hillock: The cone-shaped region where the axon emerges from the cell body, initiating the action potential.

    Neuronal Processes: Extensions of the Cell Body

    • Tracts: Bundles of axons within the CNS.
    • Nerves: Bundles of axons within the PNS.
    • Dendrites: Short, tapering, branching processes that receive incoming signals from other neurons, acting as input regions.
    • Axon: A long, single process that generates and transmits action potentials away from the cell body.
    • The axon transmits signals to other neurons or effector organs.

    Myelin Sheath: Insulating and Protecting Axons

    • The myelin sheath is a whitish, fatty (protein-lipoid) layer that surrounds most long axons, providing insulation and increasing signal efficiency.
    • Functions of the myelin sheath:
      • Protects the axon.
      • Electrically isolates axons from each other.
      • Speeds up the transmission of nerve impulses.

    Myelin Sheath Formation in the PNS

    • Schwann cells: Responsible for formation in the PNS. A Schwann cell wraps its plasma membrane around an axon to form the myelin sheath, leaving gaps called Nodes of Ranvier.
    • Neurilemma: The remaining cytoplasm and nucleus of the Schwann cell.

    Myelination in the CNS

    • Oligodendrocytes: Form the myelin sheath around axons in the CNS.
    • Nodes of Ranvier: Widely spaced in the CNS.

    White and Grey Matter: Structures of the Brain and Spinal Cord

    • White matter: Made up primarily of myelinated axons, giving it a whitish appearance.
    • Grey matter: Mostly consists of neuron cell bodies (soma) and unmyelinated axons, giving it a greyish appearance.

    Nervous System Overview

    • Master controlling and communicating system of the body.
    • Plays a vital role in monitoring internal and external stimuli, integrating information, and generating responses to activate effector organs.

    Nervous System Organization

    • Central Nervous System (CNS):
      • Consists of brain and spinal cord.
      • Acts as the integration and command center.
    • Peripheral Nervous System (PNS):
      • Includes paired spinal and cranial nerves.
      • Primarily responsible for communication between CNS and the rest of the body.

    Peripheral Nervous System Divisions

    • Sensory (Afferent) Division:
      • Carries sensory information from the body (skin, muscles, joints, and internal organs) to the CNS.
      • Consists of sensory afferent fibers and visceral afferent fibers.
    • Motor (Efferent) Division:
      • Carries motor commands from the CNS to effector organs (muscles and glands).

    Motor Division Subdivisions

    • Somatic Nervous System:
      • Controls voluntary movement of skeletal muscles.
    • Autonomic Nervous System (ANS):
      • Regulates involuntary functions of smooth muscle, cardiac muscle, and glands.
      • Divided into sympathetic and parasympathetic divisions.

    Nervous Tissue Histology

    • Composed of two primary cell types:
      • Neurons: Excitable cells responsible for transmitting electrical signals.
      • Neuroglia (Glial Cells): Supportive cells that create a supportive scaffold, insulate neurons, and promote neuron health and growth.

    Neuroglia Types and Functions

    • Astrocytes:
      • Most abundant and versatile glial cells.
      • Support and brace neurons, anchor them to nutrient sources, guide neuron migration, and control the chemical environment.
    • Microglia:
      • Small, ovoid cells with spiny processes.
      • Act as phagocytes, monitoring neuron health and removing debris.
    • Ependymal Cells:
      • Line the central cavities of the brain and spinal cord.
      • Play a role in cerebrospinal fluid production and circulation.
    • Oligodendrocytes:
      • Branched cells that wrap around CNS nerve fibers, forming myelin sheaths.
    • Schwann Cells:
      • Surround PNS nerve fibers, also forming myelin sheaths.
    • Satellite Cells:
      • Surround neuron cell bodies within ganglia, providing support and regulation.

    Neuron Structure and Function

    • Structural units of the nervous system.
    • Composed of a cell body, axon, and dendrites.
    • Long-lived, non-dividing cells with a high metabolic rate.
    • Plasma membrane plays a critical role in electrical signaling and cell-to-cell communication.

    Neuron Components

    • Cell Body (Soma):
      • Contains the nucleus, nucleolus, and is the site of protein synthesis.
      • Contains Nissl bodies, which are rough endoplasmic reticulum involved in protein production.
      • Has an axon hillock, the cone-shaped region from which axons emerge.
    • Processes:
      • Arm-like extensions from the soma.
      • Include axons and dendrites.
      • Called tracts in the CNS and nerves in the PNS.
    • Dendrites:
      • Short, tapering, and branched processes.
      • Receive input from other neurons, acting as the receptive region of the neuron.
    • Axon:
      • Single, slender process arising from the axon hillock.
      • Often covered in a myelin sheath.
      • Generates and transmits nerve impulses (action potentials).
      • Secretes neurotransmitters at the axon terminal, where it communicates with other neurons.

    Myelin Sheath

    • Whitish, fatty sheath that insulates and protects axons.
    • Functions:
      • Protects the axon.
      • Electrically insulates fibers from one another.
      • Increases the speed of nerve impulse transmission.

    Myelin Sheath Formation

    • In the PNS: Formed by Schwann cells wrapping around the axon.
    • In the CNS: Formed by oligodendrocytes.
    • Nodes of Ranvier: Gaps in the myelin sheath between adjacent Schwann cells or oligodendrocytes, where the axon is exposed.

    Gray and White Matter

    • White Matter: Primarily composed of myelinated axons, giving it a whitish appearance.
    • Gray Matter: Composed of soma, dendrites, and unmyelinated axons, appearing grayish in color.

    Nervous System

    • The nervous system is the body's master control and communication system.
    • It receives sensory input, integrates information, and generates motor output.

    Neuron Anatomy

    • Neurons are excitable cells responsible for transmitting electrical signals.
    • They consist of a cell body (soma), an axon, and dendrites.
    • Neurons are long-lived, do not divide, and have a high metabolic rate.
    • The plasma membrane of neurons plays a crucial role in electrical and cell-to-cell signaling.

    Neuron Cell Body

    • The cell body contains the nucleus and nucleolus, and is responsible for protein synthesis.
    • It is the focal point for the growth of neuronal processes.
    • Contains an axon hillock where axons originate.
    • Features chromatophilic (Nissl) bodies, which are clusters of rough ER and ribosomes that stain darkly and are involved in protein synthesis.
    • Neurofibrils are bundles of intermediate filaments that maintain the cell's structure.

    Neuron Processes

    • Dendrites are short, tapering, and branched processes that receive signals from other neurons.
    • Axons are long, slender processes that transmit nerve impulses away from the cell body.
    • Axons are specialized for generating and transmitting action potentials.
    • Axons terminate in axon terminals that release neurotransmitters.
    • Axons lack ribosomes and rely on the cell body for protein synthesis.
    • Axonal transport is the movement of substances to and from the soma, facilitated by cytoskeletal elements.

    Supporting Cells

    • Neuroglia are supporting cells that surround and wrap neurons.
    • They provide structural support, insulation, and promote the health and growth of nervous tissue.
    • CNS neuroglia include astrocytes, microglia, and oligodendrocytes.
    • Astrocytes are the most abundant and versatile glial cells, supporting neurons, controlling the chemical environment, and aiding in synapse formation.
    • Microglia are phagocytic cells that monitor the health of neurons.
    • Oligodendrocytes produce myelin sheaths that insulate axons in the CNS, increasing nerve impulse conduction speed.

    Neuron Classification

    • Neurons are classified based on the direction they transmit impulses relative to the CNS.
    • Sensory (afferent) neurons transmit impulses towards the CNS.
    • Motor (efferent) neurons carry impulses away from the CNS to effector organs.
    • Interneurons (association neurons) shuttle signals within the CNS.

    Nerve Structure

    • A nerve is a cable-like organ in the PNS, composed of bundles of axons and connective tissue wrappings.
    • Each axon within a nerve is covered by Schwann cells and a delicate connective tissue layer called endoneurium.
    • Groups of axons are bundled into fascicles by perineurium.
    • The whole nerve is surrounded by a tough fibrous sheath called the epineurium.

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    Description

    Explore the essential functions and organization of the nervous system, including its central and peripheral components. This quiz covers sensory input, integration, and motor output, essential for understanding body communication and control.

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