Essentials of Human Anatomy & Physiology Ch 7: The Nervous System Organization Quiz
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Questions and Answers

What is the function of the endocrine system in maintaining body homeostasis?

  • Releasing hormones into the blood (correct)
  • Interpreting sensory information
  • Producing electrical nerve impulses
  • Issuing instructions to body organs

    • Which organ serves as the integrating and command center of the nervous system?

  • Heart
  • Brain (correct)
  • Spinal cord
  • Endocrine system

    • What percentage of the total body weight does the adult human brain approximately weigh?

  • 1%
  • 7%
  • 5%
  • 3% (correct)

    • What is the approximate diameter of the human spinal cord?

    <p>2cm</p> Signup and view all the answers

    Which system in the body controls with rapid electrical nerve impulses?

    <p>Nervous system</p> Signup and view all the answers

    What is the weight of the spinal cord approximately?

    <p>~35g</p> Signup and view all the answers

    What is the main role of the nervous system?

    <p>Controlling and communicating with body cells</p> Signup and view all the answers

    Which term describes the ability of an organism or organ to detect external stimuli?

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

    What type of response does motor output in the nervous system lead to?

    <p>Activation of body effectors</p> Signup and view all the answers

    How does the nervous system communicate with body cells?

    <p>Via electrical impulses</p> Signup and view all the answers

    What is the general role of sensory input in the nervous system?

    <p>Gathering information about stimuli</p> Signup and view all the answers

    Which part of the nervous system decides if action is needed based on sensory input?

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

    What type of cells form a barrier between capillaries and neurons in the brain?

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

    Which type of cells dispose of debris, dead brain cells, and bacteria in the brain?

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

    Which cells produce fatty insulating coverings called myelin sheath around nerve fibers in the central nervous system?

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

    What type of cells protect and cushion neuron cell bodies?

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

    Which cells form myelin sheath around nerve fibers in the peripheral nervous system?

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

    What is the main function of neurons?

    <p>Conducting nerve impulses</p> Signup and view all the answers

    Which part of a neuron contains the nucleus and serves as the metabolic center?

    <p>Cell body</p> Signup and view all the answers

    What is the function of axons in a neuron?

    <p>Conduct impulses away from the cell body</p> Signup and view all the answers

    Where are most neuron cell bodies located?

    <p>In the gray matter</p> Signup and view all the answers

    What structures produce myelin sheaths in neurons?

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

    Which part of a neuron conducts impulses toward the cell body?

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

    What is the main function of conductivity in neurons?

    <p>Transmitting impulses to other neurons, muscles, or glands</p> Signup and view all the answers

    During depolarization of a neuron's membrane, what ion flows inside the membrane?

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

    What occurs during repolarization of a neuron's membrane?

    <p>Potassium ions rush out of the neuron</p> Signup and view all the answers

    How does the action potential move along the entire axon of a neuron?

    <p>By propagating an impulse involving sodium and potassium ions</p> Signup and view all the answers

    What part of a neuron plays a key role in communicating with another neuron at a synapse?

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

    What is the significance of myelin sheath in nerve impulse propagation?

    <p>It enhances and speeds up impulse transmission</p> Signup and view all the answers

    Study Notes

    Supporting Cells in the Nervous System

    • Astrocytes: abundant, star-shaped cells that form a barrier between capillaries and neurons, protecting from harmful substances and controlling the chemical environment of the brain.
    • Microglia: spider-like phagocytes that dispose of debris, dead brain cells, and bacteria.
    • Ependymal cells: line cavities of the brain and spinal cord, helping circulate cerebrospinal fluid and forming a protective cushion around the CNS.
    • Oligodendrocytes: produce fatty insulating coverings called myelin sheath around nerve fibers in the CNS.
    • Satellite cells: protect and cushion neuron cell bodies.
    • Schwann cells: form myelin sheath around nerve fibers in the PNS.

    Organization of the Nervous System

    • The nervous system does not work alone to regulate and maintain body homeostasis; the endocrine system is a second important regulating system.
    • The endocrine system produces hormones that are released into the blood, bringing about deliberate effects.

    Structural Classification of the Nervous System

    • The nervous system is divided into two main subdivisions: CNS (brain and spinal cord) and PNS (nerves outside the CNS).
    • The CNS acts as an integrating and command center, interpreting sensory information and issuing instructions.
    • The adult human brain weighs about 3 pounds (1,300-1,400 g) and is about 2% of the total body weight.
    • The spinal cord weighs about 35 gm, is 42-45 cm in length, and has a diameter of about 2cm.

    Functions of the Nervous System

    • The nervous system is the master controlling and communicating system of the body.
    • It has three main functions: sensory input, integration, and motor output.
    • Sensory input involves gathering information from inside and outside the body.
    • Integration involves processing and interpreting sensory input and deciding on a response.
    • Motor output involves responding to integrated stimuli, activating appropriate body effectors (muscles or glands).

    Neurons

    • Neurons are nerve cells specialized to transmit messages (nerve impulses).
    • They have three main regions: cell body, dendrites, and axon.
    • The cell body contains the nucleus and metabolic center of the cell.
    • Dendrites are armlike fibers that conduct impulses toward the cell body.
    • Axons are fibers that conduct impulses away from the cell body, ending in axonal terminals.
    • Axonal terminals contain vesicles with neurotransmitters and are separated from the next neuron by a synaptic cleft.

    Nerve Fiber Coverings and Impulses

    • Schwann cells produce myelin sheaths in a jelly-roll-like fashion, with nodes of Ranvier (gaps) at regular intervals along the axon.
    • Myelin sheaths increase the speed of impulse transmission.
    • An action potential is generated when a stimulus depolarizes the neuron's membrane, allowing sodium ions to flow in and potassium ions to flow out.
    • The sodium-potassium pump restores the original membrane configuration, requiring ATP.

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    Description

    Test your knowledge on the organization of the nervous system with this quiz based on Chapter 7 of 'Essentials of Human Anatomy & Physiology Seventh Edition' by Elaine N. Marieb. Learn about the functions, classifications, and structures of the central and peripheral nervous systems, nervous tissue, neurons, and neuroglia.

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