Neurons and Nervous System

Neuron (single-cell) level in the brain: How do individual brain cells work? Nervous system: How is the brain “hooked up” to the whole body? Whole brain. How is the brain specialized to do all it does?

Brain Cells Neurons = brain cells Ultimately all brain activity can be reduced to the “firing” of these cells Your neurons are firing right now!

Neuron Parts of the Neuron Cell Body Dendrites Axons Dendrites -Receive inputs from neighboring neurons Many, many dendrites per neuron Axons –The cell’s output structure – send info to next cell One axon per cell (“cell’s tail”)

All or None Law A neuron can’t fire just a little bit--it either “fires” or it doesn’t Technical term: action potential (means neuron firing)

Synapse Synapse = space between neurons Neurons never touch each other- (like islands) Synapse = filled with chemicals – Called neurotransmitters Chemicals from 1 neuron go out the axon –across the synapse - into the dendrite of the next neuron

Neurotransmitters are very specific – like Lock and Key Neurotransmitter molecules have specific shapes Receptor molecules have binding sites

http://www. youtube. com/watch http://www.youtube.com/watch?v=7h6Hwn9loVk&feature=relmfu&safety_mode=true&persist_safety_mode=1&safe=active http://www.youtube.com/watch?v=PKj9i1qS08M&feature=relmfu