1. The Nervous System Mission Hills High School

2. Functions of the Nervous System Sensory Sensory Integrative Integrative Motor Motor

3. Divisions of the Nervous System The nervous system is divided into The nervous system is divided into - Central Nervous System (CNS), containing the brain and spinal cord - The Peripheral Nervous System (PNS), containing the nerves and ganglia

4. The Peripheral Nervous System contains… cranial nerves which arise from the brain cranial nerves which arise from the brain Spinal nerves which arise from the spinal cord as well as many branches Spinal nerves which arise from the spinal cord as well as many branches

5. Nerve Tissue The nerve tissue is composed of two types of cells: The nerve tissue is composed of two types of cells: -neurons, which conduct impulses, and… -neuroglia which support the neurons

6. Neurons Structural and functional units of the nerve system Structural and functional units of the nerve system Perform sensory, integrative and motor functions Perform sensory, integrative and motor functions -sensory: ability to sense (receive) information -Integrative: ability to process the information received and arrive at a desire to respond. -Motor: ability to initiate a response with body movement or secretion of a product.

7. Structure of neurons Each contain a cell body with a nucleus Each contain a cell body with a nucleus Numerous dendrites: receive and send information to the cell body Numerous dendrites: receive and send information to the cell body A single axon: moves impulse from dendrites and body to dendrites or body of other neurons. A single axon: moves impulse from dendrites and body to dendrites or body of other neurons.

9. Myelin in PNS and CNS Axons in large peripheral nerves contain a fatty, supportive sheath called myelin sheath Axons in large peripheral nerves contain a fatty, supportive sheath called myelin sheath Presence of myelin makes nerve tissue appear white (white matter) Presence of myelin makes nerve tissue appear white (white matter) In CNS spinal cord, unmyelinated nerve tissue appear gray (grey matter) In CNS spinal cord, unmyelinated nerve tissue appear gray (grey matter)

10. What makes up the brain, the spinal cord or your peripheral nerves? Neurons are “the cell” Neurons are “the cell” Cell body Cell body Nucleus Nucleus Axon Axon Dendrite Dendrite What do you think surrounds the cell? What do you think surrounds the cell? What other organelles would be needed? What other organelles would be needed?

12. A nervous impulse is an electrochemical wave How might it be similar to a wave in the ocean?

13. Check it out! http://www.youtube.com/watch?v=9 euDb4TN3b0 http://www.youtube.com/watch?v=9 euDb4TN3b0 http://www.youtube.com/watch?v=9 euDb4TN3b0 http://www.youtube.com/watch?v=9 euDb4TN3b0

14. In Summary… A nervous impulse is called an action potential. A nervous impulse is called an action potential. Depolarization occurs when sodium ions enter the neuron. Depolarization occurs when sodium ions enter the neuron. Repolarization occurs when potassium ions exit the neuron. Repolarization occurs when potassium ions exit the neuron. Sodium Potassium Pumps restore the concentrations during the refractory period. Sodium Potassium Pumps restore the concentrations during the refractory period.

15. How are neurons connected? Synapses!! Synapses!!

16. Why are neurons connected?

17. More neuron connections!

18. AXON The synapse - where the action happens The next cell’s plasma membrane What is this in the membrane? Transport protein Close up look at your synapse (The Gray Matter)

19. How does the Synapse carry the signal? 1.impulse travels down the axon (The White Matter) 2. Vesicles with neurotransmitters move toward the membrane 3. Neurotransmitters are released and diffuse toward the next cell’s plasma membrane 4.The chemicals open up the transport proteins and allow the signal to pass to the next cell

20. 1 2 34 The synapse carries a signal from cell to cell

21. How many synapses are in one neuron? 1,000 to 10,000!!

22. What do you think can change neurons and their connections? Accidents Accidents Drugs Drugs Alcohol Alcohol Disease Disease

23. Drugs and alcohol bind important receptors on neurons

24. Repeated binding causes the neuron to die

25. Drugs = neuron death

26. Alcohol damages dendrites - can repair after abstinence Alcohol blocks receptors and slows down transmission

27. 100 Billion or so neurons - what’s the problem with some of them dying? Cells multiply all the time - will your neurons? Does everyone react the same way to accidents, or drugs and alcohol? Do all organisms react the same to all stimulus? Which of your activities use your neurons?

28. What if neurons die here? or here