Neurons! Message = nerve impulse The impulse travels in one direction It travels at the same speed within 1 neuron It travels with the same intensity w/in 1 neuron

Myelin sheath – keeps the electrical signal in the axon nucleus Cell body axon dendrites Myelin sheath – keeps the electrical signal in the axon Axon terminal The next dendrite

Neurotransmitters are in the “bubble” Axon terminal Dendrite of the next neuron. synapse The gap between neurons is the synapse. http://www.biologymad.com/NervousSystem/synapses.htm

http://www.biologymad.com/NervousSystem/synapses.htm

Link to another animation of the synapse Link to an explanation and animation

Drugs That Influence Neurotransmitters Change in Neurotransmission Effect on Neurotransmitter release or availability Drug that acts this way increase the number of impulses increased neurotransmitter release nicotine, alcohol, opiates release neurotransmitter from vesicles with or without impulses increased neurotransmitter release amphetamines methamphetamines release more neurotransmitter in response to an impulse nicotine block reuptake more neurotransmitter present in synaptic cleft cocaine amphetamine produce less neurotransmitter less neurotransmitter in synaptic cleft probably does not work this way prevent vesicles from releasing neurotransmitter less neurotransmitter released No drug example block receptor with another molecule no change in the amount of neurotransmitter released, or neurotransmitter cannot bind to its receptor on postsynaptic neuron LSD caffeine NIH Publication No. 00-4871