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Nerve Structure. Neuron. Used for communication between body parts May be as long as a meter. Neuron parts. Cell body (soma) Contains nucleus All info collected from dendrites Dendrite Branched extension Receives incoming signals Axon
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Neuron • Used for communication between body parts • May be as long as a meter
Neuron parts • Cell body (soma) • Contains nucleus • All info collected from dendrites • Dendrite • Branched extension • Receives incoming signals • Axon • Filament-like extension carrying signal away from cell body • Myelin Sheath • Fatty insulating cover surrounding axon • Increases speed and strength of signals
Now label on your diagram… • Axon • Dendrites • soma/cell body • Myelin sheath • Draw an arrow showing the direction of impulse travel
check your understanding… • What is a nerve cell called? • Which part of the nerve cell RECEIVES information? • Which part of the nerve cell SENDS information? • What is like the insulation around an electrical wire? • Which part of the nerve cell contains the nucleus?
Neurons interact with other neurons through synapses • Synapse ….. • junction between two neurons. • "information" flows from one neuron to another
How do neurons communicate? neurotransmitter Pre-synaptic cell Post synaptic cell (axon) (dendrite) Vesicle synapse receptors
Now label on your diagram… • Presynaptic neuron (axon) • Postsynaptic neuron (dendrite) • Synapse • Vesicles • Neurotransmitters • Receptors • Reuptake channels • Draw an arrow showing the direction of impulse travel
Neurotransmitters • Chemicals that transmit signals from a neuron to a target cell across a synapse • Acetylcholine: muscles, memory • Norepinephrine/epinephrine: fight/flight • Serotonin: mood, appetite (depression) • Histamine: Inflammation response • Dopamine: pleasure • Melatonin: sleep • Endorphins: pain control
Check your understanding… • What do you call the gap between two neurons? • What chemicals take the signal across this gap? • Name the neurotransmitter: • Sleep • Mood, appetite • Inflammation • Fight or flight • Muscles, memory • pleasure
Steps of Neuron Communication • Neuron at rest • Pre-synaptic neuron fires signal • Vesicle releases neurotransmitter • Neurotransmitter binds to receptor on post-synaptic neuron • Post-synaptic neuron fires signal • Neurotransmitters re-absorbed by pre-synaptic neuron • signal has been sent
Stimulant drugs increase number of signals fired Nicotine • Moves through spaces between neurons • Binds to nicotine receptor on pre-synaptic neuron • Causes neuron to fire • Causes release of dopamine • If you flood your brain with nicotine, brain builds MORE nicotine receptors to suck it all up
Stimulant drugs increase number of signals fired Cocaine • Present in extra-cellular space • BLOCKS reuptakechannel • Synapse is flooded with dopamine
Stimulant drugs increase number of signals fired Methamphetamine • Passes through membrane enters neuron • Moves into vesicle • Causes release of dopamine AND METH with signal • Also blocks reuptake channel