The Nervous System - PowerPoint PPT Presentation

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The Nervous System

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  1. The Nervous System Nerve Cells

  2. Nerve Cells • Called “neurons” • Three Types • Motor • Sensory • Inter

  3. Motor Neurons • Relays messages from brain or spinal cord to muscles and organs

  4. Sensory Neurons • Relays message from receptors (like in skin) to brain or spinal cord

  5. Interneurons • Makes up the brain and spinal cord • Relays messages from sensory to motor neurons


  6. Parts of a Nerve Cell • Cell body • Nucleus • Dendrites • Axon • Terminal Fibers • Synaptic Endings • Myelin Sheath

  7. Cell Body • The largest part of the cell. • It holds the general parts of the cell like the nucleus and other organelles needed for the cell to function

  8. Nucleus • Control Center of the cell • Contains most of the cell’s DNA

  9. Dendrites • Large, branching area near cell body • Brings information TO cell body • Rough Surface • Usually many per cell

  10. Axon • Branch further from cell body • Carries information AWAY from cell body • Usually only one per cell • Smooth Surface

  11. Terminal Fibers • Branches of an axon • Have synaptic endings which send neurotransmitters from one cell to another

  12. Myelin Sheath • Insulating fat layer surrounding the axon of a nerve cell. Helps messages travel Faster and stops them From leaking away

  13. What is a Nerve? • A nerve is a discrete bundle of several thousand neuron axons wrapped around each other

  14. How Do Nerves Transmit Messages?

  15. Answer: Chemicals (transmitting molecules), called neurotransmitters, are sent from axon terminal across synapse (synaptic cleft) to a receptor on a dendrite.