Soma (cell body): Contains nucleus and support systems
Dendrites: Tree-like branches that receive information from other
Axon: Long fiber that passes info to other neurons
Myelin: Fatty substance on some axons--speeds up neural
Terminal Branches of Axon: Form junctions with other cells and
contain synaptic vesicles
Synaptic vesicles: sac-like structures that contain
Synapse: The tiny gap between the sending and receiving neurons
Neural Networks: Clusters of neurons that work together and
become strengthened with use.
Neural Communication: Neurons communicate
via an electrochemical process
Resting Potential: Neuron is at rest and is said to be
Polarized (-70 milivolts). The inside of the cell is more
negative than the surrounding fluid.
Action Potential: When stimulated at or above threshold,
the cell becomes depolarized (+50 milivolts)as positively charged sodium
ions rush into the cell. The neuron has now "fired". It is an
all-or-nothing response. The cell then returns to its polarized
Refractory Period: For 1/1000 of a second after firing, the cell
cannot fire again. This is Somewhat like a camera flash recharging
1. When the action potential reaches the terminal buttons on the
ends of the terminal branches, it causes the synaptic vesicles to
release neurotransmitters into the synapse.
2. The neurotransmitters then bind to receptor sites on the receiving
neuron (like a key fitting into a lock). Some neurotransmitters
are excitatory (create a new action potential) while others are
3. After neurotransmitters have done their job, they may be destroyed by
other chemicals released into the synapse. Or, reuptake may
Reuptake: Neurotransmitters are reabsorbed by the sending
neuron and recycled for future use.
Acetylcholine (Ach): Muscle movement, learning, and memory.
An undersupply is involved in Alzheimer's disease.
Dopamine: Involved in learning, attention, and emotion. An Excess
dopamine is involved in schizophrenia.
Serotonin: Affects mood, hunger, sleep, and arousal. An
undersupply is linked to depression.
Norepinephrine: Helps control alertness and arousal. An
undersupply can lead to depression. An oversupply can lead to
GABA (gamma-aminobutytic acid): Major inhibitory
neurotransmitter. An undersupply can lead to tremors, seizures,
Glutamate: Major excitatory neurotransmitter; involved in memory.
Oversupply can overstimulate the brain leading to migraines (this is why
some people avoid MSG in food).
Endorphins: natural opiate-like neurotransmitter linked to pain
control and pleasure.
Drugs and Neurotransmitters
Agonists: Drugs that are so similar to a neurotransmitter that
they can mimic its effects-or-they may block reuptake of a
neurotransmitter. Antagonists: Drugs that inhibit a
neurotransmitters release-or-they may occupy the receptor site on the
receiving neuron, thus blocking the neurotransmitter form binding.
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