1. Understanding the Neuron

2. 2 Internal Messaging Systems 1.Nervous System- fast acting- messages travel through neurons (nerve cells) 2.Endocrine System- slower acting- messages travel through hormones

3. 3 Types of Neurons 1.Sensory- afferent- receives messages from sense organs 2.Motor- efferent- sends messages to other parts of the body 3.Inter- communicates between sensory and motor neurons

4. How Neurons Work Dendrites receive messages Pass info to SOMA; prioritizes messages to send to AXON

5. How a neural message is “Fired” Resting potential: resting axon has a – charge Action potential: when excited, pores open and + ions flow through axon “firing” an electrical pathway to the terminal button –Increase in + ions is called depolarization –the # of ions necessary for “firing” is called the threshold Once the process starts, it cannot stop: All-or- none principle. After neuron has “fired” there is a period of time where it cannot “fire” again. This is called the refractory period.

6. Action Potential… in Action

7. Synaptic Transmission The end of the axon = terminal button When electric pulse reaches TB, it converts to a chemical message which can cross the synapse = (space between neurons) –This is called a synaptic transmission

8. Neurotransmitters Chemicals that can take a message across the synaptic gap Until electric pulses to terminal button, NTs are “stored” in a sac held in the TB called a synaptic vesicle

9. Like a lock and key, specific neurotransmitters are designed to “fit” specific receptors. NTs are broken down and recycled to be reused Through reuptake, recycled NTs are sucked back into synaptic vesicles, resulting in a more muted message ***Memorize table 3.1 on page 76***

10. Plasticity Refers to neural ability to change, create new and strengthen existing connections –Means recovery is possible when brain is damaged Especially effective in children

11. Glial Cells Support neurons by holding them together and providing structural support Form myelin sheath (fatty insulation) around axons- important b/c it protects the neurons while electrically charged!