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The Nervous System and Neurons

The Nervous System and Neurons. Nervous System. Network of connected cells, tissue, and organs Controls thoughts, movement, life processes Quick responses Ex: Sunny day  pupils shrinking. CNS and PNS. Neurons. AKA: Highly specialized nerve cells

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The Nervous System and Neurons

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  1. The Nervous System and Neurons

  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: Highly specialized nerve cells • Transfer electrical impulses to and from the brain • 4 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 • Axon Terminal: End of neuron

  5. Three Types of Neurons: 1) Sensory • Detect stimuli and transmit signals to/from the brain • Detect sense (sight, smell, sound, taste, touch)

  6. Three Types of Neurons: 2) Interneuron • Located in the brain • Receive signals from the sensory neurons

  7. Three Types of Neurons: 3) Motor • Pass messages to other tissue • Ex: Nerve attached to muscle • Muscle reacts by contracting

  8. Resting Potential • Defined: Neuron at rest • Neuron exterior is positive in charge • Due to abundance of Na+ outside K+ Interior K+ K+ K+ K+ K+ K+ K+ K+ • Neuron interior is negative • Due to abundance of proteins (neg charge) • Some K+ inside the cell

  9. Action Potential • Defined: neuron at work • The electrical impulse that is triggered & moves quickly down an axon • Generating the Impulse • Na + channels in the membrane open and allow Na+ to diffuse into the cell • Area becomes positively charged (impulse) • After the Impulse • K+ channels open to allow K+ to exit the cell • Area returns to negative charge • Process continues down the axon • Na+/K+ pumps work to restore initial charge.

  10. impulse

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

  12. Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ K+ K+ Na+ Na+ Na+ Na+ Na+ K+ Na+ K+ Na+ Na+ K+ K+ K+ K+ K+ Na+ K+ Na+ Na+ K+ K+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ K+ Na+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ Na+ Na+ Na+ K+ Na+ Na+ K+ Na+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ K+ Na+ Na+ K+ Na+ Na+ Na+ K+ Na+ Na+ Na+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ Na+ K+ Na+ Na+ Na+ Na+ Na+ K+ K+ Na+ K+ Na+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+

  13. Synapse • Defined: Gap between neurons • Problem: Impulse cannot cross the gap • Solution: Neurotransmitters (chemical signals) are sent from one neuron to another • Steps: 1) Impulse reaches axon terminal (end) 2) Vesicle releases neurotransmitters into synapse, which attach to receptors on neighboring neuron 3) Na+ Channels open on dendrite of neighboring neuron… creates new impulse Neurotransmitter proteins

  14. Na+ Na+ Na+ Vesicle fuses with membrane releasing neurotransmitters. impulse impulse impulse K+ K+ K+ Impulse reaches the axon terminal Dendrite of another cell Terminal end of one cell

  15. Neurotransmitters cause Na+ channels to open… creating new impulse Neurotransmitters diffuse across the synapse and attach to receptors of a neighboring neuron Na+ Na+ Na+ impulse impulse impulse impulse K K K Dendrite of another cell Terminal end of one cell

  16. Brain impulse …. neurotransmitters impulse …. neurotransmitters impulse …. neurotransmitters impulse …. neurotransmitters impulse Feet

  17. Impulses eventually reach the muscles… and causes MOVEMENT!

  18. Review 1. What is the function of the nervous system? 2. List the 4 main parts and describe the purpose of the 4 main parts of a neuron. 3. The nervous system is divided into 2 parts. What are they and what do they include? 4. Describe the internal and external environment of a neuron in resting potential. How is resting potential reached? 5. What is a synapse and why is it a problem for neurons? 6. To what part of the nervous system do motor neurons, interneurons, and sensory neurons belong? 7. When an impulse is within a neuron it is electrical. When the signal moves to the next neuron it is _________________. What is the specific name for this signal? 8. Describe how an action potential moves down a neuron.

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