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Introduction

Complexities occurring even with simplest
function
◦ Example
synapse
Structure of the neuron
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Neuron- individual cells in our nervous system that
receive, integrate and transmit information.
Components of a neuron:
◦ A.) cell body (soma)- contains nucleus and chemical
machinery
◦ B.) Dendrites – Part of neurons that receive information
 “Branches”

Components of neuron (continued)
◦ C.) Axon- Long thin fiber that transmits signals
from cell body to other neurons.
◦ D.) Myelin Sheath- Insulating material that coats an
axon.
 Speeds up transmission
 Problems if it degrades

Easier way of thinking about axon and myelin
sheath
◦ E.) Terminal Buttons- Axon ends with a cluster of these
small knobs secreting chemicals known as
neurotransmitters.
◦ F.) Synapse – A “Gap” or junction where information is
transmitted from one neuron to another.

Summary of neural communication:
◦ Dendrites  cell body axon (coated with myelin
sheath) terminal buttons synapse at other
dendrites(where signal jumps gap)
◦ Process repeats itself
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Neural Impulse- Signal sent through neuron
Neuron at rest:
◦ Slightly negative charge
◦ Contains ions flowing back and forth
Charge is referred to as Resting Potentialcharge when a neuron is not activated

When neuron is activated, channels open allowing
in positive ions (+)
◦ Charge now becomes positive


Called Action Potential- Brief shift in neuron
charge that travels along axon.
Channel closes briefly after firing:
◦ Absolute Refractory Period- Minimum length of time after
action potential during which another action potential
can’t begin

Neurons either fire or do not (action
potentials occur or don’t)


Transmission of signals from one neuron to
another (at dendrites) occurs here
At this gap, the arrival of action potential triggers
release of neurotransmitters.

Neurotransmitter- Chemical that transmits
information from one neuron to another
◦ Play role in behavior
◦ Specific ones function at specific synapses

Example Neurotransmitters:
◦
◦
◦
◦
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Dopamine
Norepinephrine
Serotonin
Endorphins
Certain chemicals or drugs can cause increase
or decrease in release.
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Dopamine- Pleasurable emotions
Norepinephrine- contributes to mood and
arousal
Serotonin- plays role in depression
Endorphins- Body’s own internally produced
morphine like substance
◦ Plays role in pain relief