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The Nervous System: Neurons & Impulses

Explore the network of connected cells, tissue, and organs controlling thoughts, movements, and responses in the body. Learn about sensory, interneuron, and motor neurons, as well as resting and action potentials. Discover how impulses are transmitted across synapses.

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The Nervous System: Neurons & Impulses

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  1. The Nervous System

  2. Nervous System • Network of connected cells, tissue, and organs • Controls thoughts, movement, life processes • Quick responses • Ex: Sunny day  pupils shrinking

  3. CNS and PNS

  4. Neurons • AKA: Nerve Cells • Transfers electrical impulses to/from the brain • 3 Main Parts • Cell body: contains nucleus and organelles • Dendrites: branches that receive messages from neighboring cells • Axon: extension that carries messages away from the cell body

  5. Types of Neurons • Sensory • Detect stimuli and transmit signals to/from the brain • Detect sense (sight, smell, sound, taste, touch)

  6. Types of Neurons • Interneuron • Located in the brain • Receive signals from the sensory neurons

  7. Types of Neurons • Motor • Pass messages to other tissue • Ex: Nerve attached to muscle • Muscle reacts by contracting and stretching

  8. Resting Potential • Defined: Neuron at rest • Neuron Exterior: • Positive charge • Mainly Na+ outside the cell • Neuron Interior: • Negative charge (from various proteins) • K+ inside the cell

  9. Action Potential • Defined: Electrical impulse is triggered • Front end of impulse • Channels open and allow Na+ to enter the cell • Negative impulse attracted towards positive Na+ • Back end of impulse • Channels open to allow K+ to exit the cell • Interior returns to normal • Impulse pulled along by the changing of electrical charges

  10. impulse

  11. Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ K+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ negative impulse K+ K+ K+ K+ K+ K+ K+ Na+ K+ Na+ K+ K+ K+ K+ K+ K+ Na+ K+ K+ K+ Na+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+

  12. Synapse • Defined: Gap between neurons • Problem: Impulse cannot cross the gap • Solution: Impulse converted into chemical molecules (neurotransmitters) • Steps: • Impulse reaches neuron’s end • Vesicle releases neurotransmitters • Neurotransmitters attach to neighboring neuron • New impulse created

  13. Impulse stimulates a vesicle, which contains neurotransmitters Vesicle exits the cell and dissolves impulse Start of another cell End of one cell

  14. Neurotransmitters stimulate a new impulse Neurotransmitters cross the synapse and attach to receptors of a neighboring neuron impulse impulse Start of another cell End of one cell

  15. Brain …. …. …. …. Feet

  16. Motor neurons reach the muscles… • Impulse causes the muscles to stretch and contract…this causes MOVEMENT!

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