1. The Neuron The wild wonderful neuron and the nervous system

2. The Neuron  Any of the bundles of fibers interconnecting the central nervous system and all parts of the body, capable of transmitting sensory stimuli and motor impulses from one part of body to another  Nerves can be viewed as telephone lines connecting the body telling it what to do  10 trillion in body! 100 billion in brain  in Fetus, develop at 250k /min.  an individual nerve cell  each connect to 10k others  messages to and from brain travel along here  these are chemical-electrical signals “fired”  can use thousand times a minute and never stop in motion  could circle the world 22k times

4. Parts of the neuron  Synapse – gap between neurons  Receptors- cells that gather information from the senses  Effectors- cells that work the muscles and internal organs

5. Neurotransmitters  chemical messages between neurons <think of water valves)  messages must travel in one way till done or inhibited (stopped)  can be stopped by nerve damage (MS) or by other neurons acting on same one

6. Types of Neurotransmitters  ACH- controls muscle contractions  Serotonin-emotions and happiness  Dopamine-adrenaline, heart rate and blood pressure, balance  Histamine-stomach acid production  Peptides- sleepiness and arousal  Endorphins- released to relieve pain

7. Parts of the Neuron  axon - the long extension of a neuron that carries nerve impulses away from the body of the cell.  cell body (soma) - the cell body of the neuron; it contains the nucleus.  dendrites - the branching structure of a neuron that receives messages.  myelin sheath - a fatty substance that surrounds and protects some nerve fibers.

8. Types of Nervous Systems