Nervous System Overview
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Questions and Answers

What do Nissl bodies correspond to in other cells?

  • Smooth endoplasmic reticulum
  • Rough endoplasmic reticulum (correct)
  • Golgi apparatus
  • Mitochondria

    • What are neurofibrils?

    Network of fine threads within a nerve fiber that support it.

    What is the function of a dendrite?

    Conducts an impulse toward the cell body.

    What is a collateral in the context of a neuron?

    <p>A branch of an axon.</p> Signup and view all the answers

    What is an astrocyte?

    <p>Star-shaped neuroglial cell between neurons and blood vessels.</p> Signup and view all the answers

    What does an axon do?

    <p>Conducts an impulse away from the cell body.</p> Signup and view all the answers

    What is the role of an interneuron?

    <p>Transmits impulse from sensory to motor neuron within the central nervous system.</p> Signup and view all the answers

    What is a motor (efferent) neuron responsible for?

    <p>Transmits impulse out of the brain or spinal cord to effectors.</p> Signup and view all the answers

    What does a sensory (afferent) neuron do?

    <p>Transmits impulse into the brain or spinal cord from receptors.</p> Signup and view all the answers

    What is the function of an oligodendrocyte?

    <p>Myelin-forming neuroglial cell in the brain and spinal cord.</p> Signup and view all the answers

    What is a microglia?

    <p>Phagocytic neuroglial cell.</p> Signup and view all the answers

    What is an effector?

    <p>Structure capable of responding to a motor impulse.</p> Signup and view all the answers

    What does the ependyma do?

    <p>Covers the inside spaces of the ventricles and central canal.</p> Signup and view all the answers

    What is a synapse?

    <p>The small space between a neuron and the cell(s) with which it communicates.</p> Signup and view all the answers

    What is a neurotransmitter?

    <p>Chemical that an axon secretes into a synapse to stimulate or inhibit an effector or other neuron.</p> Signup and view all the answers

    What does CNS stand for?

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

    What does PNS stand for?

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

    The three general functions of the nervous system are: sensory - receiving information, integrative - deciding what to do, and motor - acting on decisions. The sensory function refers to _____

    <p>receiving information</p> Signup and view all the answers

    The autonomic nervous system controls smooth muscle, cardiac muscle, and glands and is _____

    <p>involuntary/unconscious</p> Signup and view all the answers

    The stored electrical energy across a cell membrane due to the unequal distribution of ions is known as _____

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

    The sequence of electrical changes in nerve or muscle cell exposed to a stimulus that exceeds threshold potential is known as _____

    <p>action potential</p> Signup and view all the answers

    What is a threshold potential?

    <p>Level of potential at which an action potential is triggered in a neuron.</p> Signup and view all the answers

    What is a trigger zone?

    <p>Sensitive part of an axon where an action potential is generated.</p> Signup and view all the answers

    What is a refractory period?

    <p>Period following stimulation during which a neuron or muscle fiber will not respond to another stimulus.</p> Signup and view all the answers

    What is the process of saltatory conduction?

    <p>Impulse conduction along an axon that seems to jump from one node to the next.</p> Signup and view all the answers

    What is an excitatory neurotransmitter?

    <p>Neurotransmitters that increase postsynaptic membrane permeability to sodium ions.</p> Signup and view all the answers

    What is an inhibitory neurotransmitter?

    <p>Neurotransmitters that make reaching threshold less likely.</p> Signup and view all the answers

    Study Notes

    Nervous System Overview

    • Nissl Bodies: Correspond to rough endoplasmic reticulum; involved in protein synthesis; scattered in neuronal cytoplasm.
    • Neurofibrils: Fine thread network within the nerve fiber; provide structural support to the axon.
    • Dendrites: Branching neuron processes that receive impulses and direct them towards the cell body.
    • Collateral: Branching extensions of an axon contributing to signal distribution.

    Types of Neurons

    • Axon: A single nerve fiber that transmits impulses away from the neuron’s cell body.
    • Interneurons: Connect sensory and motor neurons; function within the central nervous system to process information.
    • Motor Neurons (Efferent): Relay impulses from the CNS to effectors like muscles and glands.
    • Sensory Neurons (Afferent): Conduct impulses from sensory receptors to the CNS.

    Neuroglial Cells

    • Astrocytes: Star-shaped cells that maintain the blood-brain barrier and provide structural support in the CNS.
    • Oligodendrocytes: Form the myelin sheath around axons in the CNS.
    • Microglia: Phagocytic cells that act as immune defense within the CNS.
    • Ependyma: Line the ventricles and central canal; involved in cerebrospinal fluid production.
    • Schwann Cells: Myelinate peripheral neurons and form the neurilemma.
    • Satellite Cells: Support neurons in ganglia within the PNS.

    Neuroanatomy

    • Cell Body Features: Contains neurofibrils, Nissl bodies (protein synthesis), and the nucleus.
    • Axon Components: Includes collaterals, axon terminals, synaptic knobs, reliant on Schwann cells for myelination, and features nodes of Ranvier for signal transmission.
    • Parts of a Neuron: Dendrites, cell body, and axon form the core structure.

    Physiological Principles

    • Action Potential: Describes the nerve impulse; a sequence of electrical changes following stimulation.
    • Threshold Potential: Minimum level required to trigger an action potential in a neuron.
    • Saltatory Conduction: Rapid impulse conduction across myelinated axons, jumping between nodes of Ranvier.
    • Refractory Period: Time post-stimulation when a neuron is non-responsive to additional stimuli.

    Synaptic Mechanism

    • Synapse: Junction between neurons; consists of presynaptic and postsynaptic neurons.
    • Neurotransmitters: Chemicals released into synapses to stimulate or inhibit target cells; include excitatory and inhibitory types.
    • Synaptic Transmission: Process where impulses from the presynaptic neuron influence the postsynaptic neuron.

    Membrane Dynamics

    • Membrane Potential: Electrical difference across a cell membrane due to ion distribution.
    • Resting Potential: Established when a neuron is inactive; key for creating action potentials.
    • Synaptic Potential: Changes in postsynaptic membrane potential following neurotransmitter release.

    Nervous System Functions

    • Three Main Functions:
      • Sensory: Receives and processes environmental stimuli.
      • Integrative: Evaluates sensory information and makes decisions.
      • Motor: Carries out responses by activating effectors.

    Nervous System Subdivisions

    • Central Nervous System (CNS): Comprises the brain and spinal cord.
    • Peripheral Nervous System (PNS): Encompasses cranial and spinal nerves; facilitates communication between the CNS and the body.

    Neuron Classification

    • Multipolar Neurons: Multiple processes; most common type found in the CNS.
    • Bipolar Neurons: Two distinct processes; involved in sensory pathways.
    • Unipolar Neurons: Single process diverging into peripheral and central branches; primarily found in sensory neurons.

    Tissue Appearance

    • Myelinated Axons: Appear white and conduct impulses rapidly.
    • Unmyelinated Tissue: Appears gray; generally slower in impulse conduction.

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    Quiz Team

    Description

    Explore the essential components of the nervous system, including Nissl bodies, neurofibrils, and various types of neurons. This quiz covers the roles and structures of axons, interneurons, motor and sensory neurons, as well as neuroglial cells. Test your knowledge of how these elements interact to maintain neural function.

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