2. The Nervous System

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

4. CNS and PNS

5. AKA: Nerve Cells Transfers electrical impulses to/from the brain 3 Main Parts 1)Cell body: contains nucleus and organelles 2)Dendrites: branches that receive messages from neighboring cells 3)Axon: extension that carries messages away from the cell body Neurons

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

7. Interneuron – Located in the brain – Receive signals from the sensory neurons Types of Neurons

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

9. 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

10. 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

11. imp ulse

12. Na + 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+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+ negative impulse K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+

14. 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

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

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

18. Feet Brain ….

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