1. Nervous System All you could ever Want to know about the nervous system and its anatomy

2. Nervous System  Communication Is greatest key to success during any activity Your body constantly communicates and responds to stimuli so it can complete tasks  Stimulus: something that causes a response In order to be successful and keep you healthy, your systems must be aware at all times the situations going on in your body

3. Nervous System & Endocrine System  Nervous System: Controls thoughts, movements, and simpler life processes such as swallowing.  Endocrine System: helps control growth, development, and responses to your environment.

4. Parts of the Nervous System  Central Nervous System (CNS): includes the brain and spinal cord. Interprets  Peripheral Nervous System (PNS): a network of nerves that transmits messages to the CNS and from the CNS to other organs in the body

5. Parts of the Nervous System  Neuron Main cell Passes messages (electrical impulses) throughout the body 3 types  Motor- carry impulses away from the brain Stimulates muscles and glands  Interneuron- connects and carries info between motor and sensory neurons  Sensory- carry information from sense organs to the spinal cord and brain

6. Cells of the Nervous System  These cells come in all shapes and sizes  Generic nerve cell shape and size below Cell BodyNucleus Axon Dendrites Axon Terminal

7. Cells of the Nervous System  Cell Body Main portion of the cell Most activities take place in this area  Dendrites Short branched extensions Carry impulses from the environment or other neurons to the cell body

8. Cells of the Nervous System AAxon Long extension off of the cell body Carries messages away from the cell body towards another cell MMyelin Sheath Insulating cells that usually appear around the axons of neurons NNodes Gaps between the myelin sheath that help increase the speed of impulse travel

11. Different Kinds of Nerve Cells Main cell type  neuron Support cells  glial  Oligodendrocytes  Astrocytes  Schwann Cells

12. Neurons – how do they work?  Impulse Is the movement of an electric current through a nerve cell  Caused by Stimuli  Something that excites a reaction in another object Stimuli come from  External environment  Internal environment

13. How it works The resting nerve  When the nerve is resting (not telling anything what to do) The outside is slightly positive The inside is slightly negative  Happens because the cell is constantly moving + ions out of the cell  The cell is not actually “negative” but when comparing inside and out, it is less positive This difference in charge is called  Resting potential

14. Resting Nerve

15. Active Nerve: beginning  Remains at “rest” until a stimulus hits it  The stimulus Must be large enough to cause a reaction  Called threshold level of the cell  If the stimulus is below the threshold, nothing happens  If it is above, the cell responds  Referred to as an all or none response

17. Active Nerve  If the stimulus is large enough A reaction begins This reaction causes protein channels to open  These channels are found all along the neuron (numbering in the 1000’s)  They allow the positive ions that were being pumped out, to move back in  Each channel opens after the one before it  This continues down the entire length of the axon

18. Active Nerve  The inside of the cell quickly becomes more positive than the outside  Because the channels do not open all at once, it allows the impulse to travel down the axon  This reversal of charges is call an “Action potential”

19. Active nerve

20. Returning to rest  After the reaction leaves a certain area + ions begin to slowly move back out by diffusion And the cell resumes pumping other + charges back out as it did before the stimulus hit it

22. End of a nerve  Finally, the potential hits the end of a nerve where it will pass the signal to another nerve The area where two nerves meet is called  Synapse There is a gap between two nerves  Called synaptic cleft

23. End of a nerve To get the impulse across nerves use neurotransmitters  Chemicals that can pass signals along (neurotransmitters)  They attach to the next nerve and cause a new reaction

24. Neurotransmitters in vesicles

25. Review  Nervous system function?  Main cell found in the nervous system?  Parts of a typical nerve?  Nerve activity?