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Nervous System Overview

Functions of the Nervous System

  • Sensory: Senses stimuli from within the body and the external environment.

  • Integrative: Analyzes, interprets, and stores information about stimuli.

General Organization of the Nervous System

Central Nervous System (CNS)

  • Includes:

    • Brain

    • Spinal Cord

Peripheral Nervous System (PNS)

  • Includes:

    • Spinal Nerves (31 pairs)

    • Cranial Nerves (I-XII pairs)

    • Subdivisions

Central Nervous System (CNS) Functions

  • Sorts incoming sensory information

  • Generates thoughts and emotions

  • Forms and stores memories

  • Stimulates muscle activity

Peripheral Nervous System (PNS) Structure

Spinal and Cranial Nerves

  • Spinal Nerves: 31 pairs

  • Cranial Nerves: I-XII pairs

Divisions of PNS

  • Autonomic Nervous System (ANS): Involuntary control

    • Sympathetic: "Fight or Flight"

    • Parasympathetic: Rest and digest

  • Somatic Nervous System (SNS): Voluntary control

Autonomic Nervous System (ANS)

  • Contains sensory neurons from the viscera that convey information to the CNS.

  • Contains efferent neurons for smooth muscle, cardiac muscle, and glands (unconscious control).

Somatic Nervous System (SNS)

  • Composed of sensory neurons that convey information from cutaneous and special sense receptors to the CNS.

  • Contains motor neurons that conduct impulses from the CNS.

Functions and Structures of Neurons

  • Functions:

    • Sensing

    • Remembering

    • Thinking

    • Controlling muscle activity

    • Controlling glandular secretions

  • Structure:

    • Cell Body (Soma): Contains nucleus, cytoplasm, organelles

    • Dendrites: Tapered, highly branched processes

    • Axon: Transmits impulses away from the cell body

Neuroglial Cells

Functions of Neuroglia

  • Support, nurture, and protect neurons.

  • Types of Neuroglia in CNS:

    • Astrocytes: Form blood-brain barrier, soak up excess ions and toxins.

    • Microglia: Phagocytic cells that protect CNS.

    • Oligodendrocytes: Produce myelin sheath around neurons.

    • Ependymal Cells: Line brain ventricles and central canal of spinal cord, form cerebral spinal fluid.

Schwann and Satellite Cells (Neuroglia of PNS)

  • Schwann Cells: Produce myelin sheaths around PNS neurons.

  • Satellite Cells: Provide structural support and soak up excess ions.