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How is the Nervous System
Organized?
Chapter 3-Neuroscience:
The Brain and Behavior
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Class Objectives:
Identify and define the structures of
the neuron
Identify and discuss the role of
neurotransmitters on behavior
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The Neuron
The neuron is the basic building
block of the nervous system
‐ They are often grouped in bundles
called nerves.
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4 parts of the neuron
1.
Dendrites are specialized to receive signals
from neighboring neurons and carry
them back to the cell body
Thin, bushy-like structures that receive
information from outside the neuron
‐
Relays the information into the cell body
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The Neuron
2.
The Cell body
contains the
cell nucleus
The cell body
relays the
information
down to the
axon
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The structure of a neuron
3.
Axon: A thin, long structure that
transmits signals from the cell body to
the axon terminal.
4.
Axon Terminal is the last step for the relay
of information inside the neuron.
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The cell
body is
covered
with Axon
Terminals
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Once the information hits the
terminal, it is transmitted
outside the cell by
neurotransmitters, which reside
in the axon terminal.
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How do Neurons
Communicate?
-Electrical Communication
-Chemical Communication
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The Electrical Part
Action potential is an electrical current
sent down the axon.
The activity within the neurons is
electrical. This current causes the
neuron to “fire”
‐
This is an “all-or-none” process
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Action potentials travel down the axon like
a wave of energy
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Synaptic transmission
The Synapse is the space between neurons
‐ The synaptic gap or cleft
•
•
Information must be transmitted across
the synapse to other neurons via the
neurotransmitters.
This is an electrochemical process
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Let’s Review!
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Now, Let’s DANCE!
Time to do the Neuron Dance
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__________
Presynaptic Neuron
________
________
____________
________________________
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Neurotransmitters
Neurotransmitters are chemical
substances that reside in the axon
terminals
• They communicate to other neurons by
binding to receptors on neighboring
neurons
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Chemical Communication
The communication between neurons is
chemical
Neurotransmitter are either neutralized
by an enzyme or taken back up by the
neuron that released it in reuptake.
‐ At least 50 different types of
neurotransmitters have been identified
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Chemical Communication
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Synaptic Transmission
The neurotransmitters are released from
the vesicles and then attach to receptors
located on the postsynaptic neuron.
These neurotransmitters are in contact
with the dendrite of the postsynaptic
neuron only briefly.
‐ The chemical is almost immediately
destroyed or reabsorbed
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Neurotransmitters
At least 50 different types of
neurotransmitters have been identified
‐
‐
‐
‐
‐
‐
Acetylcholine
GABA
Serotonin
Dopamine
Norepinephrine
Endorphins
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Acetylcholine
Activates motor neurons controlling
skeletal muscles
Contributes to the regulation of attention,
arousal and memory
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Examples of Neurotransmitters
Gamma-aminobutyric acid (GABA) is
involved in experiences of anxiety,
alcohol abuse, seizure disorders, and
sleep disorders
Serotonin is involved in sleep and
mood regulation and appetite (appetite
for carbohydrates)
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Dopamine
Involved in movement, thought
processes, emotion, feelings of reward
and pleasure
Implicated in schizophrenia, attention
deficit disorder, and drug abuse
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Norepinephrine
Involved in arousal reactions (increasing
heart rate, respiration, sweating, and
dilation of pupils)
May also be involved in hunger, eating,
and sexual activity
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How do drugs effect
behavior?
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Drugs Impact on the Brain
Common drugs can alter the amount of a
neurotransmitter released at the synapses
Some drugs can mimic/facilitate the action of
the neurotransmitters while others can block
the action of the neurotransmitter.
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Agonists versus Antagonists
Agonists mimic or facilitate the actions of a
neurotransmitter
Antagonists oppose/block the actions of a
neurotransmitter
Agonist
Antagonist
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Next Class…
The Brain
How do the neurons work together?
‐ The Central Nervous System
‐ The Peripheral Nervous System
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