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ORGANIZATION OF THE NERVOUS SYSTEM

ORGANIZATION OF THE NERVOUS SYSTEM. FUNCTIONS. SENSORY MOTOR COGNITIVE. ANATOMICAL ORGANIZATION of the NERVOUS SYSTEM. Central Nervous System (CNS). Unpaired, bilaterally symmetrical structures extending along the longitudinal axis of the midsagittal plane of the body.

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ORGANIZATION OF THE NERVOUS SYSTEM

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  1. ORGANIZATION OF THE NERVOUS SYSTEM

  2. FUNCTIONS • SENSORY • MOTOR • COGNITIVE

  3. ANATOMICAL ORGANIZATION of the NERVOUS SYSTEM

  4. Central Nervous System (CNS) • Unpaired, bilaterally symmetrical structures extending along the longitudinal axis of the midsagittal plane of the body. • Structures arising directly from the neural tube. • Includes: Brain Spinal cord

  5. Peripheral Nervous System • (PNS) • Made up of transmission pathways carrying information between the CNS and external/internal environments. • Afferent (sensory) pathways: Carry information to the CNS. • Efferent (motor) pathways: Carry information from the CNS.

  6. Peripheral Nervous System • Includes: Cranial nerves (12 pairs) Spinal nerves (31 pairs) • Also includes sensory receptors in skin and wall of gut tube as well as in tendons and skeletal muscles. • Also includes motor end plates between motor neurons and skeletal muscle fibers.

  7. Autonomic Nervous System • May be considered a subdivision of the PNS. • Entirely motor. • Innervates smooth muscle and glands (viscera)

  8. ANS Subdivisions • Sympathetic system (fight or flight) Also called thoracolumbar • Parasympathetic system (feed and breed) Also called craniosacral

  9. Parts of a Neuron • Cell body: Trophic unit Perikaryon • Dendrites: Receptive unit • Axon: Conductive unit

  10. Cell Body • That part of a neuron that encloses the nucleus and other organelles necessary to maintain and repair neuron.

  11. Cell Body Organelles • Nucleus • Golgi apparatus • RER Ribosomes =Nissl substance

  12. Dendrites • Branches off the cell body that carry information to the cell body. • Usually several to many. • Relatively short. • Often branched. • Have receptors for neurotransmitters. • Conduct local potentials.

  13. Axon • That part of the neuron that carries information to another neuron or muscle cell. • Usually relatively long. • Single. • Conducts action potential (nerve impulse)

  14. Axon • Ends in short branched processes called: Telodendria: Give off endings called terminal boutons. Terminal boutons contain synaptic vesicles of neurotransmitters. • May have collateral branches.

  15. Axon • Cell membrane is called the axolemma. • Cytoplasm is called the axoplasm.

  16. Axon • Contains: Mitochondria Neurofilaments Neurotubules

  17. Axonal Transport • Anterograde • Retrograde • Slow transport • Fast transport

  18. Axon • Covered by neurolemma: Made up of Schwann cells. • Often myelinated: Myelin is formed by Schwann cells. • Note: axon is only part of neuron that is ever myelinated.

  19. General Terminology • Nucleus: Aggregation of dendrites and nerve cell bodies in the CNS. • Ganglion: Aggregation of dendrites and nerve cell bodies in the PNS.

  20. General Terminology • Nerve: Bundle of fibers (axons) in the PNS. • Tract: Bundle of fibers (axons) in the CNS. • Commissure: Tract in the CNS that crosses from one side to the other.

  21. General Terminology • White matter: Areas of myelinated axons. • Gray matter: Areas of unmyelinated axons, cell bodies, and dendrites.

  22. Functions of the CNS • Refer to p. 63 in syllabus

  23. Spinal Nerve Branches • Dorsal primary ramus • Ventral primary ramus • Ramus recurrens • White ramus communicans • Gray ramus communicans

  24. Spinal Nerve Branches • Paravertebral ganglion • Splanchnic nerve • Prevertebral ganglion

  25. Reflex Arc • Afferent (sensory) pathways: Somatic. Visceral (splanchnic). • Efferent (motor) pathways: Somatic. Visceral (splanchnic). • Association neurons (interneurons).

  26. Synapse • Components: Presynaptic membrane: With synaptic vesicles filled with neurotransmitters. Synaptic cleft: Postsynaptic membrane: With receptors for neurotransmitters. • Monosynaptic pathways. • Polysynaptic pathways.

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