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PSY110 Psychology
Module 5 – Neurons: The Basic Elements of Behavior - Pages 50-62
Structure of the
 Cell Body (soma)
Neuron
 Axon – single, long, sending arm
 Dendrite – many, short, receiving arm
 Myelin sheath – insulating coverings of axon
 Terminal Buttons – bulge at end of axon containing
neurotransmitters
How Neurons Fire
 Stimuli from dendrites produce action potential
 Action potential (electrical nerve impulse) - Positive to
negative reversal that prorogates down axon
 Action potential speed – 2mph-225mph (thicker
sheathed neuron transmit faster)
Neuron to neuron
 Synapse – gap between terminal button on axon and the
dendrite (or body) of another neuron
 Nerve impulse triggers the release of neurotransmitter
chemicals into the synapse
 Neurotransmitters (> 100 different chemicals) tend to
behave as either excitatory or inhibitory (their effect
varies at different sites)
 Dendrites have specialized receiving sites for both
excitatory and inhibitory neurotransmitters
 Enough excitatory neurotransmitters will trigger an
action potential in the dendrite
 Inhibitory neurotransmitters mediate the potential of
triggering the dendrite
 Synaptic neurotransmitters are either neutralized by
enzymes or reabsorbed (reuptake) into the axon
Major
 Acetylcholine (ACh) (Excitatory) – Muscle & Cognitive
Neurotransmitters
 Glutamate (Excitatory) – Memory
 Gamma-amino butyric acid (GABA) (Inhibitory) –
Eating, Aggression, & Sleeping
 Dopamine (DA) (Inhibitory or Excitatory) – Muscle &
Mental Disorders
 Serotonin (Inhibitory) – Sleeping, eating, mood, pain,
depression
 Endorphins (Mostly Inhibitory) – Pain suppression,
pleasure, appetite
Multimedia
Run Interactivity 5-1 from student CD
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Richard Goldman